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Contents

1. Introduction

1.1 About the Book

1.2 PV overview and history

1.3 SPV at CEL

1.2 Why Solar?

1.3 Energy Requirements

1.4 Demystify the Myths

1.5 Characteristics of Solar Energy

1.5.1 Solar energy – an outline

1.5.2 Cost effectiveness

1.5.3 External costs of conventional electricity generation

2. Solar Energy Solutions and Systems

2.1 Applications of solar energy as a renewable source

2.1.1 Solar thermal energy

2.1.2 Solar photovoltaic energy

2.2 Insolation spread

2.3 Capturing and harnessing Solar Energy

2.1.1 Solar photovoltaic effect

2.1.2 Solar cell

2.1.3 Balance of systems

2.4 Types of PV systems

2.4.1 Stand-alone systems

2.4.2 Grid Connected Systems

2.5 Operation

3 System Components

3.1 Photovoltaic system components

3.2 The Solar panel

3.2.1 Types of Modules

3.2.2 Solar panel parameters

3.3 Battery

3.3.1 Battery Bank

3.3.2 Types of Batteries

3.3.3 Temperature effect

3.4 Power charge regulator

3.5 Converter

3.5.3 DC-DC converter

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3.5.4 DC-AC converter

3.5.5 Additional features of inverter

3.6 Equipment or Load

3.7 Power conditioning unit

3.8 Junction Boxes

3.9 Wiring

3.10 Balance of system standards

4 Design

4.1 Introduction and basic principles

4.2 System type selection

4.3 Home Appliances

4.4 Illustration and Flowchart for design of habitat PV system

4.5 Design process

4.5.1 Load estimation

4.5.2 Inverter rating

4.5.3 Daily energy supplied by the inverter

4.5.4 System voltage

4.5.5 Battery capacity

4.5.6 Consider for battery autonomy

4.5.7 Daily energy generated by panels

4.5.8 Solar radiation, capacity and number of panels

4.6 Wire sizing

4.7 Factors affecting performance of a PV system

5. Installation and commissioning

5.1 Safety

5.1.1 Electrical

5.1.2 Chemical

5.1.3 Handling

5.1.4 Points to check before wiring.

5.1.5 Points to check when selecting the installation location

5.2 Assembly

5.2.1 Configuration

5.2.2 Mounting

5.2.3 Connection

5.3 Battery

5.3.1 Site

5.3.2 Connection

5.3.3 Earthing

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5.4 Control Equipment

5.4.1 Inverter connections

5.4.2 Wiring

5.5 System Commissioning

5.5.1 Visual Check

5.5.2 Connections

5.5.3 Testing output of solar panel

5.5.4 Applying Power

5.5.5 Recommissioning

5.6 Parts and Tools

5.6.1 Standard parts

5.6.2 Roof tile parts

5.6.3 Measurement

5.6.4 Tool kit

6. Application

6.1 Habitat application

6.1.1 Solar lanterns

6.1.2 Domestic Habitat lighting and fan

6.1.3 Outdoor and street lighting

6.1.4 Water pumping

6.2 Industrial application

6.2.1 ONGC offshore power

6.2.2 Low power TV transmitter

6.2.3 Obstruction warning light at airport

6.2.4 Railway signalling(supplementary power)

6.2.5 Telecom towers

6.3 Defence Use

6.3.1 Lightweight foldable solar charger for Manpack Radio Equipment

6.3.2 Lightweight foldable solar charger for Manpack Wireless

Communication Equipment SCU-01

7. Maintenance and Troubleshooting

7.1 Light units’ not glowing and no low battery indication on charge

controller

7.2 No charging indication on the charge controller

7.3 Low duration

7.4 Incident switch off

7.5 Breakage

7.6 Lamp flickering

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7.7 Lamp semi glow

7.8 Lamp blackening

7.9 No indication

7.10 Water entry or insect entry

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List of figure

Fig.1.1 SPV module for unmanned offshore applications

Fig.1.2 SPV module with screen printed liquid cast encapsulation technique

Fig.1.3 SPV modules of different types of solar cells

Fig. 1.4 SPV modules during 90’s with increased efficiency

Fig. 1.5 mono crystalline SPV module

Fig.1.6 Solar insolation over India

Fig. 1.7 India’s energy balance – India has had a negative energy balance for decades

which has forced the purchase of energy from outside the country.

Fig: 1.8 Energy consumption in power sector (2005)

Fig: 1.9 Per capita Residential Electricity demand (kWh/per person)

Fig 1.10 India’s electricity use breakdown in commercial and residential buildings

Fig 1.11 Actual power production capacity of a solar PV system

Fig 1.12 sustainable energy solution

Fig 1.13 Various layouts for panel grafting on urban households.

Fig 1.14 Evolution of competitive solar technology.

Fig 1.15 Azure Power's 2-megawatt photovoltaic plant in the state of Punjab

Fig 1.16 A 5-megawatt solar photovoltaic power plant has been installed at village

Rawara, Taluka Phalodi, in Rajasthan

Fig. 2.1 An example of a solar water heating system (antifreeze is used so that the

liquid does not freeze if outside temp. drops below freezing)

Fig 2.2 Electricity in a typical solar cell

Fig 2.3 Process of production of electricity in a solar power plant

Fig 2.4: 10-MW solar power plant in Barstow, California.

Fig 2.5 Solar radiation map of India

Fig 2.6: Flow of energy in a solar PV system

Fig 2.7(a) p-n junction silicon semiconductor

Fig 2.7(b) A solar cell connected to an ammeter showing a deflection when exposed

to light.

Fig 2.8: photovoltaic solar cell to photovoltaic solar array

Fig 2.9 A PV system showing the balance of components

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Fig 2.10 A Lead Acid battery

Fig 2.11(a) Discharging process of a lead acid battery

Fig 2.11(b) Charging process of a lead acid battery

Fig 2.12 Nickel Cadmium Battery

Fig 2.13 Charge Controller

Fig 2.14 Solar inverters

Fig 2.15(a): A circuit diagram of solar installation with DC and AC loads

Fig 2.15(b) Flow chart of a stand-alone system

Fig 3.1: A basic solar PV system.

Fig 3.2: A working model of the basic solar PV system at CEL

Fig 3.3: The connection of cells to form a solar panel.

Figure 3.4: Different IV Curves. The current (A) changes with the irradiance, and the

voltage (V) changes with the temperature.

Fig 3.5: The different components of a solar panel.

Fig 3.6: The solar panel parameters and their role in efficiency calculation.

Fig 3.7: Interconnection of panels in parallel. The voltage remains constant while the

current duplicates.

Fig 3.8: A 24V, 150Ah battery interconnection at CEL.

Fig 3.9: The specifications of a Valve Regulated Lead Acid Battery.

Fig 3.10: The specifications of Rechargeable Lead Acid Tubular Positive Plate

Battery.

Fig 3.11: Circuit diagram of a charge controller.

Fig 3.12: A realization of the inverter with a transformer with a movable switch and

a current source.

Fig 3.13: The output achieved from the inverter with the subsequent harmonics.

Fig 3.14: A Single phase transistor bridge inverter

Fig 3.15: 500 kW, 3 phase inverter

Fig 3.16: The components of a power conditioning unit.

Fig 3.17: The cable requirements

Fig 3.18: A three-panel solar array diagram.

Fig 3.19: A directly connected solar power dc pump diagram.

Fig 3.20: Battery-backed solar power–driven dc pump.

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Fig 3.21: Stand-alone hybrid solar power system with standby generator.

Fig 3.22: Grid-connected hybrid solar power system with standby generator.

Fig 4.1: India’s first two megawatt grid connected project, commissioned in the state

of West Bengal in east India.

Fig 4.2: Some of the appliances which can be run by solar PV system

Fig 4.3 Series and parallel connection of batteries to supply the required energy to the

load considering 2 days’ autonomy

Fig 4.4: Series and parallel connection of PV modules with their ratings that are

required to supply the energy to the load.

Fig 4.5 Complete design of solar PV system to fulfill the required load as described in

the example

Fig 4.6: Sun’s path during summer and winter

Fig 4.7: The effect of temperature on the IV characteristics of a solar cell.

Fig 4.8: Solar panels with dirt and dust settled on it

Fig 4.9: Amorphous solar panel

Fig 4.10 Polycrystalline solar cell

Fig 4.11 Mono crystalline solar cell

Fig 5.1: Chemical handling apparatus

Fig 5.2 PV module safety

Fig 5.3 Examples of poor roof condition

Fig 5.4 Azimuthal angle

Fig 5.5: Wind pressure

Fig 5.6 A schematic diagram of the proposed system.

Fig 5.7 Module Mounting

Fig 5.8: picture of EXIDE solar battery

Fig 5.9 Schematics showing electrical connections

Fig 5.10: Picture of a charge controller

Fig 5.11: Inverter for 1MegaWatt power station

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List of flowchart

Flowchart 1.1: Technology & types of PV cell.

Flowchart 2.1: the processes involved in the production of a solar cell

Flowchart 2.2 Flow chart of a grid tied system

Flowchart 2.3 operation with AC & DC load

Flowchart 4.1: design of habitat PV system

Flowchart 5.1 an overview of the entire process of installation of solar panels

Flowchart 5.2: Going ahead with installation of PV system

Flowchart 5.3 Creating a Stand-Alone Mount

Flowchart 5.4 Roof Mounting

Flowchart 5.5 making electrical wiring connections

Flowchart 5.6: Inverter connections

Flowchart 5.7 testing process flow

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List of table

Table 1.1 Conversion efficiencies of various PV module technologies

Table 1.2: Overview of the usage of SPV systems in India

Table 3.1: The BoS items / components with BIS Standards specifications

Table 4.1 Power rating of some home appliances

Table 4.2 illustrative habitat appliance use in a day

Table 4.3: Calculation of load in Watt-hr

Table 4.4: Illustrative power (watt) use per day

Table 4.5: Tilt angle as per geographic latitude

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1. Introduction

1.1 About the Book

The focus of making this “Reference handbook and Do it Yourself guide” is to create

an enabling environment for solar technology penetration in the country both at a

centralized and decentralized level and on promoting off-grid systems to serve

populations without access to commercial energy and modest capacity addition in

grid-based systems.

This guide will familiarize you with the fundamentals of design and installation of

your Solar Power System. The guide also serves to illustrate the simplicity and

efficiency of solar design when equipment is developed in unison with each other.

If you are familiar with residential construction techniques, AC wiring, and your

local permitting requirements you will have the basic skills to install your Solar

Power System.

This guide was created by summarizing common requirements of solar design. It

serves to prepare system designers with a basic understanding of the solar design

and planning process. Designers are encouraged to research the specific demands of

the permitting jurisdiction and utility governing their region. Your installation

should be performed in full compliance with safety standards and all relevant

jurisdictional requirements, including if applicable, the Indian National Electrical

Code (“NEC”).

1.2 “PV” overview & history

PV cells are made of light-sensitive semiconductor materials that use photons to

dislodge electrons to drive an electric current. There are two broad categories of

technology used for PV cells, namely

Crystalline silicon, as shown which accounts for the majority of PV cell

production;

Thin film, which is newer and growing in popularity.

The “family tree” gives an overview of these technologies available today.

The type of silicon that comprises a specific cell, based on the cell manufacturing

process. Each cell type has pros and cons. Mono-crystalline PV cells are the most

expensive and energy intensive to produce but usually yield the highest efficiencies.

The modules made from Polycrystalline silicon crystals are approximately 14%

efficient and are extremely good value for money. Amorphous solar modules are not

too susceptible to shading and are suited to low light levels.

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PV cell types

Cryatalline Silicon(Wafer Based)

Thin Film Special

Poly Crystalline

Mono Crystalline

Amorphous Sia-Si

TandemA-Si/microcrystalline

CIGSCopper Indium

Gallium Selenide

CdTeCadmium Telluride

Dye SensitizedTiO2

Compound SemiconductorEg: GaAs based

Commercially Available(see list of Manufacturers

in Annexure)

Under R&D or pilot stage not commercially available

Flowchart 1.1: Technology & types of PV cell.

Crystalline Silicon Technologies: Crystalline cells are made from ultra-pure silicon

raw material such as those used in semiconductor chips. They use silicon wafers that

are typically 150-200 microns (one Fifth of a millimeter) thick.

Thin Film Technologies: Thin film is made by depositing layers of semiconductor

material barely 0.3 to 2 micrometers thick onto glass or stainless steel substrates. As

the semiconductor layers are so thin, the costs of raw material are much lower than

the capital equipment and processing costs.

Conversion Efficiency: Apart from aesthetic differences, the most obvious

difference amongst PV cell technologies is in its conversion efficiency

Technology Module Efficiency

Mono-crystalline Silicon 12.5-15%

Poly-crystalline Silicon 11-14%

CIGS (Copper Indium Gallium Selenide) 10-13%

CdTe (Cadmium Telluride) 9-12%

Amorphous Silicon (a-Si 5-7% Table 1.1 Conversion efficiencies of various PV module technologies

Apart from aesthetic differences, the most obvious difference amongst PV cell

technologies is in its conversion efficiency.

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1.3 SPV @ Central Electronics Limited

The SPV activity in India was confined within few national laboratories with R&D

activities till 1975 where the developmental activity was directed towards laboratory

scale solar cell fabrication oriented towards possible future space applications.

The activity at CEL extending over more than four decades and half can be seen as,

1975-80 : R&D phase

1981-85 : Pilot plant Operation

1986-91 : Industrial Scale technology Proving and Semi-Commercial operations

1991-2000 : Commercial Operation

2000onwards : Technology innovation for adoption of green energy and meeting

energy needs of fast developing nation

Evolving solar panels at CEL:

The development of solar cells for terrestrial applications was initiated at CEL

following Governments decision, in 1975, to mount concerted efforts in its high

technology area. CEL has carried out Extensive in-house R&D work spanning a

decade for developing the complete technology for the manufacture of silicon solar

cells and modules and designing, engineering and operating a pilot plant for

production of such cells and modules based on the process technology and

production engineering so developed. The activity also so included the development

of a whole range of SPV systems and undertaking large volume commercial

production, supply, field installation and commissioning of such systems.

Starting with processing of 38mm diameter hyper pure silicon wafers using vacuum

metallization in 1978, CEL went through an evolutionary development process in

terms of both different sizes of cells and the whole range of process technology from

making them. It now manufactures, using technology completely developed in-

house, 100mm diameter n+-p junction solar cells starting CZ solar grid silicon wafer

and employing low cost techniques of texturization, screen-printed silver

metallization, antireflection coating and the state of art lamination technology.

Fig.1.1 SPV module for unmanned offshore applications

The ONGC module is a pioneering intrinsically safe

double glass module developed specifically for

operation in explosion prone environments, such as on

the offshore, oil production platforms of ONGC. These

are the 1st modules in the world to be certified with Gr.I, Gr.IIA and Gr.IIB by

Central Mining Research Station (CMRS), Dhanbad and accepter by international

insurers, Lloyds of U.K.

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Fig.1.2 SPV module with screen printed liquid cast

encapsulation technique

The screen printing process for the metallization of

silicon solar cells uses the thick film technique giving

scope for more automation in manufacturing thereby

increasing efficiency and reducing the processing cost to about 60% as compared to

the conventional vacuum evaporation technique.

Fig.1.3 SPV modules of different types of solar cells

During 80’s CEL has undergone rigorous technological

innovation for increasing efficiency and reducing the

cost of production of solar cells. The size and structure

of solar cells varied, 4” diameter solar cell was

introduced, Lamination technology bringing with it

automation in manufacturing process.

Fig. 1.4 SPV modules during 90’s with increased efficiency

CEL demonstrates the importance of entering an area

of advanced technology at early stage in the evolution

of technology and building indigenous capacity to

convert science into technology and further for

industrial and domestic use. CEL, working for more

than four decades has built up an internationally

recognised capability in SPV area of integrating

Science, Technology, and Industry.

Fig. 1.5 mono crystalline SPV module

CEL, with its commitment to harness the solar energy,

has opened up new vistas in the field of solar

photovoltaic. Backed by an integrated production

facility to manufacture Mono-Crystalline Silicon Solar

Cells and Modules with the state-of-the-art screen-printing technology, the company

has supplied more than 1.5 Lakhs SPV Systems in India and abroad, covering both

rural and industrial applications.

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1.4 Why SOLAR?

India is a tropical country, where sunshine is available for longer hours per day and

in great intensity. Solar energy, therefore, has great potential as future energy

source. It also has the advantage of permitting the decentralized distribution of

energy, thereby empowering people at the grassroots level.

India is endowed with vast solar energy potential. About 5,000 trillion kWh per year

energy is incident over India’s land area with most parts receiving 4-7 kWh per sq. m

per day. Theoretically, a small fraction of the total incident solar energy (if captured

effectively) can meet the entire country’s power requirements.

Fig.1.6 Solar insolation over India

Source: http://www.esri.com/mapmuseum

It is also clear that given the large

proportion of poor and energy un-

served population in the country, every

effort needs to be made to exploit the

relatively abundant sources of energy

available to the country and it is in this

situation the solar imperative is both

urgent and feasible to enable the

country to meet long-term energy needs

and also from an energy security

perspective, solar is the most secure of

all sources, since it is abundantly

available.

Hence both technology routes for conversion of solar radiation into heat and

electricity, namely, solar thermal and solar photovoltaic, can effectively be harnessed

providing huge scalability for solar in India. Solar also provides the ability to

generate power on a distributed basis and enables rapid capacity addition with short

lead times.

1.5 Energy Requirements

Almost 400 million Indians—about a third of the subcontinent’s population—don’t

have access to electricity. This power deficit, which includes about 100,000 un-

electrified villages, places India’s annual per-capita electricity consumption at just

639 kilowatt hours—among the world’s lowest rates.

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Since the 1980’s, and still currently, India has encountered a negative balance in

overall energy consumption and production. This has resulted in the need to

purchase energy from outside the country to supply and fulfill the needs of the

entire country. The Government is more sensitive to renewable energy potential and

has started to put reforms and projects, incentives and legislation in place to

convince investors and companies to make the shift.

Fig. 1.7 India’s energy balance –

India has had a negative energy

balance for decades which has forced

the purchase of energy from outside

the country.

(Source: U.S. Energy Information

Administration)

The breakdown of energy sources for power production of India in 2005. India is a

large consumer of coal, which makes up more than 57% of its total consumption.

Fig: 1.8 Energy consumption in

power sector (2005)

(Source:www.presidentofindia

.nic.in)

India relies heavily on coal energy to produce electricity. A strong second is hydro

power, followed by natural gas. The consumption of all renewable energies

represents fully one third of the total consumption.

India now ranks third amongst the coal producing countries in the world. Being the

most abundant fossil fuel in India till date, it continues to be one of the most

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important sources for meeting the domestic energy needs. It accounts for 55% of the

country’s total energy supplies.

Through sustained increase in investment, production of coal increased from about

70 MT (million tones) (MoC 2005) in early 1970s to 382 MT in 2004/05. Most of the

coal production in India comes from open pit mines contributing to over 81% of the

total production while underground mining accounts for rest of the national output

(MoC 2005). Despite this increase in production, the existing demand exceeds the

supply. India currently faces coal shortage of 23.96 MT.

Stressing the need to find new energy sources, a top PSU official said India is likely

to run out of its 60-70 billion tonnes of coal reserves by 2040-41 if the demand

continues to grow at the present pace.

“The demand for coal will reach two billion tonnes mark by 2016-17. We need

to grow at the rate of 17-18 per cent from the present 6-7 per cent to meet this

growing demand,” Coal India Ltd (CIL) Chairman Partha S Bhattacharyya said at

the ICC Coal Summit.

With coal reserves expected to run out in the next 45 years in the country,

there is a greater need to switch to renewable sources of energy. Poor quality of

power supply and frequent power cuts and shortages impose a heavy burden on

India’s fast-growing trade and industry.

The access gap is complicated by another problem more than three-quarters

of India’s electricity is produced by burning coal and natural gas. With India’s

rapidly-growing population— currently 1.1 billion—along with its strong economic

growth in recent years, its carbon emissions were more than 1.6 billion tons in 2007,

among the world’s highest.

The only light of hope is the fact that with harnessing of solar energy, the

country can generate nearly 50,000 MW of solar power by 2050, the capacity of

which could be further enhanced to over 75,000 MW.

India has been facing electricity shortages in spite of appreciable growth in

electricity generation. The demand for electrical energy has been growing at the

faster rate and shall increase at higher growth rate to match with the projected

growth of Indian economy.

The map shown below shows the individual per capita demand of the individual

states of the country.

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Fig: 1.9 Per capita Residential Electricity demand (kWh/per person)

(Source: CEA, 2009a)

The demand is maximum in the states like Tamil Nadu, Kerala, Maharashtra,

Gujarat and Rajasthan, the states which account for a major share in the unparalleled

solar potential of India.

Fig 1.10 India’s electricity use breakdown in commercial and residential buildings.

(Source: Bassi, n.d.)

In a typical commercial building in India, it is estimated that about 60% of the total

electricity is used for lighting, 32% for space conditioning as well as 8% for heating

ventilation and air‐conditioning.

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1.6 Demystifying the Myths

1. Myth: Solar is too expensive for widespread usage and will therefore never

compete with conventional means of power generation.

Facts:

o The cost of solar technologies has declined every year since they were

first introduced onto the market in the 50s

o The reduction in cost has been driven by improved research and

technology, and most of all by steady increases in sales volume

o The average growth rate of PV manufacturing in India is 35 percent in

the past 3 years

o Every ton of conventional, nonrenewable energy used adds to an

overall shortage and therefore makes this kind of energy more

expensive to locate and to use

o Solar on the other hand is a renewable resource and an immense

amount of solar energy strikes the Earth's surface every day

2. Myth: Solar is not feasible for my energy needs.

Facts:

o India receives solar energy equivalent to more than 5,000 Trillion kWh

per year, which is far more than its total annual energy consumption

o The average solar insolation in India is 4-7 kWh/square meter.

o The peak power of a solar panel is estimated for 1000W/m2.

Fig 1.11 Actual power production capacity of a solar PV system

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(It produces 2.3 kW – power enough to operate 10 household lamps of 23W

(example) for 10 hours.)

o The fixed and one time installation cost for 1kW SPV system is a mere amount

of Rs2, 70,000* ((INR)(current rate under MNRE for standalone system), where

as it will have a lifetime of 30 years with lowest of maintenance cost and one

time free battery replacement by CEL**.

o For grid interactive hybrid SPV system the cost of installation is even a

smaller amount of Rs 180* per Watt.

(* The rate mentioned is not inclusive of subsidy or any relaxation. Subsidy

may vary from state to state as well as in hilly and plain areas)

(** Provided CEL is the SPV system installer)

3. Myth: Solar systems is not a sustainable solution.

Facts:

Considering various perspectives individually:

Self reliance

o The per capita average annual domestic electricity consumption in

India in 2009 was 96 kWh in rural areas and 288 kWh in urban

areas for those with access to electricity.

o The production capacity of solar systems can easily meet the above

demands keeping in mind the rich solar potential of India.

o The average life of a solar system is 25years and hence a cost

effective, long run and permanent setup unaffected by the ever

changing conventional source market.

Community upliftment

o At a fixed capital investment it can generate substantial revenues

when setup as a hybrid grid connected system.

o In field regions, off-grid setups can meet the demands of agro-

pumping, water heating systems etc.

National contribution

o It is a clean energy.

o It will cut down on the existing 20% of power losses in transmission

and distribution by the provision of stand alone systems in the rural

and isolated areas.

o It will reduce the pressure on the environment.

All of the above together will build a sustainable solution.

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Fig 1.12 sustainable energy solution

4. Myth: Solar power is not practical in urban areas

Facts:

o Solar energy systems are installed at the point of use eliminating the

need to trench underground and dig up asphalt

o No extra land space is needed making urban installation practical

Fig 1.13 Various layouts for panel grafting on urban households.

o Solar power systems give off no noise or pollution, making them the

ideal renewable energy source in urban areas

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5. Myth: Solar is not competitive with the conventional energy market.

Facts:

I. First generation cells consist of large-area, high quality and single

junction devices.

Fig 1.14 Evolution of competitive solar technology.

II. The most

successful second

generation

materials have

been cadmium

telluride (CdTe),

copper indium

gallium Selenide,

amorphous

silicon and micro

-morphous

silicon. These

materials are applied in a thin film to a supporting substrate such as

glass or ceramics reducing material mass and therefore costs. These

technologies do hold promise of higher conversion efficiencies,

particularly CIGS-CIS, DSC and CdTe offers significantly cheaper

production costs.

III. Third generation technologies aim to enhance poor electrical

performance of second generation (thin-film technologies) while

maintaining very low production costs.

There are a few approaches to achieving these high efficiencies:

o Multi-junction photovoltaic cell (multiple energy threshold devices). o Modifying incident spectrum (concentration). o Use of excess thermal generation (caused by UV light) to enhance voltages or

carrier collection. o Use of infrared spectrum to produce electricity at night.

Plummeting prices of polysilicon, a raw material used in solar modules, could make power from solar photovoltaic plants as cheap as Rs 5 a unit or less by 2015 against Rs 12 a unit as estimated today.

6. Myth: Solar energy and solar designs work well only in warm, sunny climates

Facts:

o Solar technologies can work efficiently and cost-effectively anywhere

in India, even in cloudy communities

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o Energy-storage systems make solar technologies in less sunny regions

practical

o Some photovoltaic systems store electricity in batteries so that energy

can be retrieved later -- even after up to 30 consecutive days without

sunlight

7. Myth: Solar electricity cannot serve any significant fraction of Indian

electricity needs.

Facts:

o With about 300 clear, sunny days in a year, India's theoretical solar

power reception, on only its land area, is about 5 Petawatt-hours per

year (PWh/yr) (i.e. 5 trillion kWh/yr or about 600 TW). The daily

average solar energy incident over India varies from 4 to

7 kWh/m2 with about 1500–2000 sunshine hours per year (depending

upon location), which is far more than current total energy

consumption

o Assuming the efficiency of PV modules were as low as 10%, this would

still be a thousand times greater than the domestic electricity demand

projected for 2015

8. Myth: To collect enough solar energy a business needs to install

large arrays of collectors requiring vast land area.

Facts:

o There is sufficient roof space on most businesses to produce the total

electricity needed using existing photovoltaic technology.

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1.7 Characteristics of Solar Energy

1.7.1 Solar Energy- An Outline

A new era for solar power is approaching. Long derided as uneconomic, it is

gaining ground as technologies improve and the cost of traditional energy sources

rises. Within three to seven years, unsubsidized solar power could cost no more to

end customers in many markets, than electricity generated by fossil fuels or by

renewable alternatives to solar.

i. Indian SPV energy scenario

Presently, India have over 17.5 GW (June 2010) of installed renewable energy

(Wind =11.8 GW, Small Hydro =2.8 GW, PV installed=15 MW, Rest is mostly

Biomass) capacity. Out of this installed PV, the grid tied and off grid tied share are

12.3 MW (less than 0.1% of grid tied renewable energy) and 2.9 MW (0.7% of off grid

renewable capacity of India). Although, sun provides 10,000 times more energy, we

daily consume and India being a tropical country receives adequate solar irradiance

(Daily radiation ~ 4-7 KWh/m2, solar energy received= 5,000 trillion KWh/year,

Sunny days/year = 250-300) which is a major driver for the SPV market in the

country.

Presently, SPV based applications usage in India is not in accordance with

that in the global market (Globally, grid-connected PV applications account for 75%

while in India it account only ~ 3% of the overall PV applications) as much of the

country does not have an electrical grid. Table below shows the different mode of

use of SPV systems in India.

Table 1.2: Overview of the usage of SPV systems in India

Sources/Systems Cumulative

Achievement

(2008-09)

Cumulative Achievement

(2009-10)

Distributed Renewable Power

Solar power 8.01 MWp 9.13 MWp

Decentralized Energy Systems

Solar Street Lighting 70,474 nos. 88,297 nos.

Home Lighting System 4,34,692 nos. 5,84,461 nos.

Solar Lantern 6, 97,419 nos. 7, 92,285 nos.

SPV Power Plants 2.12 MWp 2.41 MWp

SPV Pumps 7,148 nos. 7,334 nos.

India is gradually shifting focus towards its solar energy program as the use

and implication of SPV is very low in the country. The Government is striving hard

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to push the SPV industry by introducing grid based incentives and concessions in

various duties in the recent budget (2010-11) to make the country as a global leader.

Driven by an increasing demand for electricity, wide gap between demand and

supply and pressure to reduce greenhouse gas emission, India has targeted 22 GW

(20 GW grid and 2GW off grid tied) of Solar Power by 2022 in its Jawaharlal Nehru

National Solar Mission (JNNSM). Out of this, around 50 % will be produced through

solar photovoltaic (SPV). Ministry of New and Renewable Energy (MNRE) is aiming

to achieve 500 MWp grid-connected SPV capacities by 2017. It is estimated that the

Indian solar energy sector will grow at 25% per year in next few years.

ii. Latest steps of Indian Market on the global front are

India inaugurated Azure Power's 2-megawatt photovoltaic plant in the state of Punjab, the first privately owned, utility-scale power plant on the Asian subcontinent.

Fig 1.15 Azure Power's 2-megawatt photovoltaic plant in the state of Punjab

Built under a 30-year power purchase agreement with the Punjab State Electricity Board, the plant will help power 4,000 rural homes for 20,000 people.

Farooq Abdullah, minister of new and renewable energy, said the plant

showcases India's pledge to generate 20,000 megawatts from solar power by 2022 under the country's national solar mission.

An Rs 67-crore, 5 megawatt solar photovoltaic power plant has been installed

at village Rawara, Taluka Phalodi, in Rajasthan. The project, owned by Indian Oil

Corporation, was commissioned by Rajasthan Electronics & Instruments Ltd under the

Jawaharlal Nehru National Solar Mission, as stated by Ministry of Heavy Industries.

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Fig 1.16 A 5-megawatt solar photovoltaic power plant has been installed at village Rawara, Taluka Phalodi, in Rajasthan

This power plant is designed to feed power to 33/132 kV grid sub-station at village Bap, which is situated 18 km from plant site Rawara. It is expected to generate energy of 67 lakh KWh a year.

1.7.2 Cost Effectiveness

The decrease in manufacturing costs and retail prices of PV modules and systems (including electronics and safety devices, cabling, mounting structures, and installation) have come as the industry has gained from economies of scale and experience. This has been brought about by extensive innovation, research, development and ongoing political support for the development of the PV market. Reductions in prices for materials (such as mounting structures), cables, land use and installation account for much of the decrease in BOS costs. Another contributor to the decrease of BOS and installation-related costs is the increase in efficiency at module level. More efficient modules imply lower costs for balance of system equipment, installation related costs and land use. Electricity price evolution

Costs for the electricity generated in existing gas and coal-fired power plants are constantly rising. This is a real driver for the full competitiveness of PV. Energy prices are increasing in many regions of the world due to the nature of the current energy mix. The use of finite resources for power generation (such as oil, gas, coal and uranium), in addition to growing economic and environmental costs will lead to increased price for energy generated from fossil and nuclear fuels.

1.7.3 External costs of conventional electricity generation

The external costs to society incurred from burning fossil fuels or nuclear power generation are not currently included in most electricity prices. These costs are both local and, in the case of climate change, global. As there is uncertainty about the magnitude of these costs, they are difficult to quantify and include in the electricity prices.

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The market price of CO2 certificates remains quite low (around €14/tonne CO2 end of 2010) but is expected to rise in the coming decades.

BENEFITS OF SOLAR ENERGY OVER DISTRIBUTED GRID ENERGY

As a distributed energy resource available nearby load centers, solar energy could reduce transmission and distribution (T&D) costs and also line losses. According to World Resources Institute (WRI), India’s electricity grid has the

highest transmission and distribution losses in the world – a whopping 27%. Numbers published by various Indian government agencies put that number at 30%, 40%, and greater than 40%. Solar technologies like PV carry very short gestation periods of development and, in this respect, can reduce the risk valuation of their investment. They could enhance the reliability of electricity service when T&D congestion occurs at specific locations and during specific times. By optimizing the location of generating systems and their operation, distributed generation resources such as solar can ease constraints on local transmission and distribution systems. They can also protect consumers from power outages. For example, voltage surges of a mere millisecond can cause brownouts, causing potentially large losses to consumers whose operations require high quality power supply. Moreover, the peak generation time of PV systems often closely matches peak loads for a typical day so that investment in power generation, transmission, and distribution may be delayed or eliminated.

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2. Solar Energy Solutions and systems

2.1 Applications of solar energy as a renewable source

There are two main applications:

2.1.1 Solar thermal energy

Solar thermal energy (STE) is a technology for harnessing solar energy for thermal

energy. Solar collectors capture the energy of the sun and convert it into heat. The

basic idea of a solar collector is that the solar energy passes through a layer of

glazed glass where it is absorbed by the underlying material resulting in heat. The

glazing of the glass prevents heat from escaping, thereby effectively capturing the

heat.

Fig. 2.1 An example of

a solar water heating

system (antifreeze is

used so that the

liquid does not freeze

if outside temp. drops

below freezing)

Solar thermal collectors are as low, medium, or high-temperature collectors.

Low-temperature collectors are flat plates generally used to heat

swimming pools.

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Medium-temperature collectors are also usually flat plates but are

used for heating water or air for residential and commercial use. The

applications include solar drying and distillation.

High-temperature collectors concentrate sunlight using mirrors or

lenses and are generally used for electric power production.

STE is different from photovoltaic, which converts solar energy directly into

electricity.

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2.1.2 Solar Photovoltaic energy

Photovoltaic (PV) is a method of generating electrical power by converting solar

radiation into direct current electricity using semiconductors that exhibit the

photovoltaic effect. This is explained in more detail in the following sections.

Fig 2.2 Electricity in a typical solar

cell

Photovoltaic power generation

employs solar panels composed of a

number of solar cells containing a

photovoltaic material.

Due to the growing demand for renewable energy sources, the manufacturing of

solar cells and photovoltaic arrays has advanced considerably in recent years.

Solar photovoltaic is growing rapidly, albeit from a small base, to a total global

capacity of 40 GW (40,000 MW) at the end of 2010.

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Fig 2.3 Process of production of electricity in a solar power plant

Source: Energy Information Administration: Schott Corporation.

Fig 2.4: 10-MW solar power plant in

Barstow, California.

More than 100 countries use solar PV.

Installations may be ground-mounted

(and sometimes integrated with farming

and grazing) or built into the roof or

walls of a building (building-integrated

photovoltaic).

2.2 Insolation spread

We receive energy from the sun in the form of solar radiation. Solar panels make

use of this radiation to generate electricity. The amount of solar radiation that

strikes a single location over a given period of time (usually one day) is called

insolation.

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Fig 2.5 Solar radiation

map of India

As can be seen from the

Solar Radiation Map of

India - most parts are

suitable for generating

power from Solar

Energy. The most

suitable areas are

Rajasthan, Gujarat,

Madhya Pradesh,

Maharashtra, Andhra

Pradesh, Karnataka,

Punjab, Haryana, Uttar

Pradesh, Uttarakhand,

Jharkhand, Tamil Nadu,

Orissa, and West

Bengal.

In general major Geography of Country is suitable for Solar Energy Utilization.

2.3 Capturing and harnessing solar energy

Fig 2.6: Flow of energy in a solar

PV system

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2.3.1 Solar photovoltaic effect

Fig 2.7(a) p-n junction silicon

semiconductor

The photovoltaic effect is the means by

which solar panels or photovoltaic

modules generate electricity from light.

A solar cell is made from a

semiconductor material such as silicon.

Impurities are added to this to create

two layers,

i. n-type material, which has too many electrons.

ii. p-type material, which has too few electrons.

The junction between the two is known as a p-n junction. This process is known

as doping.

Fig 2.7(b) A solar cell connected to an

ammeter showing a deflection when

exposed to light.

Do it yourself: Get p-n junction silicon

semiconductor, connect one end of wire

to the p-type and n-type. Now connect

an ammeter to the other end and

complete the circuit and place it in sunlight

Light consists of packets of energy called photons. When these photons hit the

cell, they are either reflected, absorbed or pass straight through, depending on

their wavelength. The energy from those which are absorbed is given to the

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electrons in the material which causes some of them to cross the p-n junction. If an

electrical circuit is made between the two sides of the cell a current will flow. This

current is proportional to the number of photons hitting the cell and therefore the

light intensity.

2.3.2 Solar cell

A solar cell is any device that directly converts the energy in light into electrical

energy through the process of photovoltaic.

Fig 2.8: photovoltaic solar cell to

photovoltaic solar array

The performance of a solar or

photovoltaic (PV) cell is measured

in terms of its efficiency at

converting sunlight into electricity.

There are a variety of solar cell

materials available, which vary in

conversion efficiency.

Flowchart 2.1: the processes

involved in the production of

a solar cell

Solar cell plants like the one

in CEL take the wafer

through a high technology

semiconductor processing

sequence to create working

solar cells. In c-Si, wafers

typically undergo a process

sequence of etching,

diffusion, and screen-

printing steps before they are

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tested and graded for incorporation into modules.

The final part of the overall manufacturing process is the solar system assembly

and installation. First, an array structure is chosen for the mechanical integration

of the solar module. This array structure will depend on the final location of the

system, which could involve retrofitting onto a roof, integrating into building

materials for roofs or vertical walls, or pole-mounting, ground-mounting, or

attaching to an industrial structure.

2.3.3 Balance of systems

Fig 2.9 A PV system showing

the balance of components

In addition to purchasing

photovoltaic panels you will

need to invest in some

additional equipment (called

"balance-of-system") to

condition and safely transmit

the electricity to the load that

will use it

The major balance-of-system equipments for systems are:

1. Batteries

Batteries accumulate excess energy created by your PV system and store it to be

used at night or when there is no other energy input. Batteries can discharge

rapidly and yield more current that the charging source can produce by itself, so

pumps or motors can be run intermittently. There are two types of batteries;

i. Lead Acid Batteries

ii. Nickel Cadmium Batteries

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i. Lead Acid Batteries

Lead Acid Batteries are made of five basic components:

A resilient plastic container.

Positive and negative internal plates made of lead.

Plate separators made of porous synthetic material.

Electrolyte, a dilute solution of sulphuric acid and water, better known as

battery acid.

Lead terminals, the connection point between the battery and whatever it

powers.

Fig 2.10 A

Lead Acid

battery

1. Discharging process

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Fig 2.11(a) Discharging process of a lead acid battery

2. Charging process

2.11(b) Charging process of a

lead acid battery

ii. Nickel Cadmium

Batteries

Fig 2.12 Nickel Cadmium

Battery

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Source: Encyclopedia Britannica, Inc.

The Nickel-cadmium battery uses nickel oxide in its positive electrode (cathode), a

cadmium compound in its negative electrode (anode), and potassium hydroxide

solution as its electrolyte. The Nickel Cadmium Battery is rechargeable, so it can

cycle repeatedly.

As the battery is discharged, the following reaction takes place:

Cd + 2H2O + 2NiOOH —> 2Ni(OH)2 + Cd(OH)2

2. Charge controller

A solar charge controller is needed

in virtually all solar power systems

that utilize batteries. The job of the

solar charge controller is to regulate

the power going from the solar

panels to the batteries.

Overcharging batteries will at the

least significantly reduce battery

life and at worst damage the

batteries to the point that they are

unusable.

Fig 2.13 Charge Controller

3. Inverter

The function of an inverter is to transform the low voltage DC of a lead acid

battery into higher voltage AC which may be used to power standard ‘mains’

appliances. An inverter is necessary where appropriate low voltage appliances are

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unavailable or expensive or in larger systems where it is necessary to distribute

the power over a wide area.

Fig 2.14 Solar inverters

The amount of

equipment needed

depends on what you

want the use of the

system is. In the

simplest systems, the

current power generated

by is connected directly

to the load. However, if

the energy is required to be store batteries and charge controller are required.

Depending on the needs, balance-of-system equipment could account for half of

the total system costs. The system supplier will be able to tell exactly what

equipment are needed

2.4 Types of PV systems

2.4.1 Stand Alone systems

These systems are generally employed where there is no availability of grid

power. The system operates autonomously and supplies power to the electrical

loads independent of the electric utility. The energy created by the Solar Panel

array is stored in batteries. Whenever electricity is a needed, the energy is drawn

from batteries.

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Figure 2.15(a): A circuit diagram of solar installation with DC and AC loads

Fig 2.15(b) Flow chart of a stand-alone system

The major balance-of-system equipments for stand-alone systems are:

Batteries

Charge controller

Power conditioning equipment

Safety equipment

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Meters and instrumentation

2.4.2 Grid Connected systems

A grid-connected system powers the home or small business with renewable

energy during those periods when the sun is shining. Any excess electricity

produced is fed back into the grid. When renewable resources are unavailable,

electricity from the grid supplies your needs, thus eliminating the expense of

electricity storage devices like batteries.

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105

Flowchart 2.2 a grid tied system

If more electricity is used than the system feeds into the grid during a given

month, the difference between what energy used and produced is to be paid.

The balance of system components required are:

Power conditioning equipment

Safety equipment

Meters and instrumentation.

2.5 Operation

Flowchart 2.3 operation with AC &

DC load

The solar modules convert solar

energy directly into dc power

which can be used directly by dc

loads and also by ac loads with the

use of an inverter. A battery

charges and discharges according

to the requirement of the

household or establishment.

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3. System Components

A basic photovoltaic system consists of five main components: i. the solar panel

ii. the batteries

iii. the regulator

iv. the load

v. the converter

The panels are responsible for collecting the energy of the sun and generating

electricity.

The battery stores the electrical energy for later use.

The regulator ensures that panel and battery are working together in an optimal

fashion.

The load refers to any device that requires electrical power, and is the sum of the

consumption of all electrical equipment connected to the system. It is important to

remember that solar panels and batteries use direct current (DC). If the range of operational voltage of your equipment does not fit the voltage supplied by your battery, it will also be necessary to include some type of converter.

If the equipment that you want to power uses a different DC voltage than the one supplied by the battery, you will need to use a DC/DC con-verter. If some of your equipment requires AC power, you will need to use a DC/AC converter, also known as an inverter. Every electrical system should also incorporate various safety devices in the event

that something goes wrong. These devices include proper wiring, cir-cuit breakers,

surge protectors, fuses, ground rods, lighting arrestors, etc.

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3.1 Photovoltaic system components

The Solar Panel

• The solar panel is composed of solar cells that collect solar radiation and transform it into electrical energy. This part of the system is sometimes referred to as a solar module or photovoltaic generator.

• Panel arrays can be made by connecting a set of panels in series and/or parallel in order to provide the necessary energy for a given load. Electricity will vary according to climatological conditions, the hour of the day, and the time of the year.

• The most common production technology is crystalline silicon, and can be either monocrystalline or polycrystalline. Amorphous silicon can be cheaper but is less efficient at converting energy to electricity. New solar technologies, such as silicon ribbon and thin film photovoltaics, promise higher efficiencies but are not yet widely available.

The Battery

• The battery stores the energy produced by the panels that is not immediately consumed by the load. This stored energy can then be used during periods of low solar irradiation. The battery component is also sometimes called the accumulator.

• The most common type of batteries used in solar applications are maintenance-free lead-acid batteries, also called recombinant or VRLA (valve regulated lead acid) batteries.

• Aside from storing energy, sealed lead-acid batteries also serve two important functions:

• They are able to provide an instantaneous power superior to what the array of panels can generate, needed for motors.

• They determine the operating voltage of your installation.

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The Regulator

• The solar power charge regulator assures that the battery is working in appropriate conditions. It avoids overcharging or overdischarging the battery, both of which are very detrimental to the life of the battery.

• To ensure proper charging and discharging of the battery, the regulator maintains knowledge of the state of charge (SoC) of the battery. The SoC is estimated based on the actual voltage of the battery.

• By measuring the battery voltage and being programmed with the type of storage technology used by the battery, the regulator can know the precise points where the battery would be overcharged or excessively discharged.

• The regulator can include other features like ammeters, voltmeters, measurement of ampere-hour, timers, alarms, etc. While convenient, none of these features are required for a working photovoltaic system.

The Converter

• The electricity provided by the panel array and battery is DC at a fixed voltage. The voltage provided might not match what is required by your load. A direct/alternating (DC/AC) converter, also known as inverter, converts the DC current from your batteries into AC.

• If necessary, you can also use converters to obtain DC at voltage level other than what is supplied by the batteries.

• For optimal operation, you should design your solar-powered system to match the generated DC voltage to match the load.

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Putting it all together The complete photovoltaic system incorporates all of these components.

When all of the components are in balance and are properly maintained, the system

will support itself for years.

The Load

• The load is the equipment that consumes the power generated by your energy system. The load may include wireless communications equipment, routers, workstations, lamps, TV sets, VSAT modems, etc.

• In the general system it is absolutely necessary to use efficient and low power equipment to avoid wasting energy.

Solar Panels

•The solar panels generate power when solar energy is available.

The Regulator

•The regulator ensures the most efficient operation of the panels and prevents damage to the batteries.

The Battery Bank

•The battery bank stores collected energy for later use.

Converters and

Inverters

•Converters and inverters adapt the stored energy to match the requirements of your load.

The Load

• Finally, the load consumes the stored energy to do work.

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Fig 3.1: A basic solar PV system.

Fig 3.2 : A working model of the basic solar PV system at CEL.

3.2 The solar panel An individual solar panel is made of many solar cells. The cells are electrically

connected to provide a particular value of current and voltage. The individual cells

are properly encapsulated to provide isolation and protection from humidity and

corrosion.

Fig 3.3 : The connection of cells to form a solar panel.

There are different types of modules available on

the market, depending on the power demands of

your application. The most common modules are

composed of 32 or 36 solar cells of crystalline

silicon. These cells are all of equal size, wired in

series, and encapsulated between glass and

plastic material, using a polymer resin (EVA) as

a thermal insulator. The surface area of the

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module is typically between 0.1 and 0.5 m2. Solar panels usually have two electrical

contacts, one positive and one negative. Some panels also include extra contacts to allow the installation of bypass diodes

across individual cells. Bypass diodes protect the panel against a phenomenon

known as “hot-spots”. A hot-spot occurs when some of the cells are in shadow while

the rest of the panel is in full sun. Rather than producing energy, shaded cells behave

as a load that dissipates energy. In this situa-tion, shaded cells can see a significant

increase in temperature (about 85 to 100ºC.) Bypass diodes will prevent hot-spots on

shaded cells, but reduce the maximum voltage of the panel. They should only be

used when shading is unavoidable. It is a much better solution to expose the entire

panel to full sun whenever possible.

Figure 3.4 : Different IV Curves.

The current (A) changes with the

irradiance, and the voltage (V) changes

with the temperature.

The electrical performance of a solar

module its represented by the IV

char-acteristic curve, which

represents the current that is

provided based on the voltage

generated for a certain solar radiation.

The curve represents all the possible values of voltage-current. The curves depend

on two main factors: the temperature and the solar radiation received by the cells.

For a given solar cell area, the current generated is directly pro-portional to solar

irradiance (G), while the voltage reduces slightly with an increase of temperature. A

good regulator will try to maximize the amount of energy that a panel provides by

tracking the point that provides maximum power (V x I). The maximum power

corresponds to the knee of the I-V curve.

3.2.1 Types of modules

Fig 3.5 : The different components of a solar panel.

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Various module classifications are used commercially. The general term 'module' (or panel) is defined more precisely by highlighting the module's specific qualities. Modules can be classified according to: • Cell type:

- mono-crystalline modules; - polycrystalline modules; - thin-film modules (amorphous, CdTe and CIS modules).

• Encapsulation material: - teflon modules; - PVB modules; - resin modules (the EVA classification module is not generally used). Encapsulation technology: - lamination (with EVA, PVB or teflon; see the following section on 'Laminates').

• Substrate: - film modules; - glass-film modules (or glass-Tedlar modules); - metal-film modules; - acrylic plastic modules; - glass-glass modules.

• Frame structure: - framed modules; - frameless modules.

• Construction-specific additional functions: - toughened safety glass (TSG) modules; - laminated safety glass (LSG) modules; - insulating glass modules; - insulating glass modules for overhead glazing; - stepped insulating glass modules; - laminated glass modules.

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3.2.2 Solar Panel Parameters

*Note:- The panel

parameters values change

for other conditions of

irradiance and

temperature.

Manufacturers will

sometimes include graphs

or tables with values for

conditions different from

the standard. You should

check the performance

values at the panel

temperatures that are

likely to match your

particular installation. Fig 3.6 : The solar

panel parameters

and their role in

efficiency

calculation.

Panel

parameters for system sizing To calculate the

number of

panels required

to cover a given load, you just need to know the current and voltage at the point of

maximum power: IPmax and VPmax.

You should assume a loss of efficiency of 5% in your calculations to compensate for

the inadequacy of the panel to work at the maximum power point at all the times.

Interconnection of panels A solar panel array is a collection of solar panels that are electrically inter-connected

and installed on some type of support structure. Using a solar panel array allows

you to generate greater voltage and current than is possible with a single solar panel.

The panels are interconnected in such a way that the voltage generated is close to

(but greater than) the level of voltage of the batteries, and that the current generated

is sufficient to feed the equip-ment and to charge the batteries. Connecting solar panels in series increases the generated voltage. Connecting

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panels in parallel increases the current. The number of panels used should be

increased until the amount of power generated slightly exceeds the demands of your

load. It is very important that all of the panels in your array are as identical as possible. In

an array, you should use panels of the same brand and characteristics because any

difference in their operating conditions will have a big impact on the health and

performance of your system.

Fig3.7: Interconnection of panels in parallel. The voltage remains constant while the

current duplicates.

3.3 The battery The battery “hosts” a certain reversible chemical reaction that stores electrical energy that can later be retrieved when needed. Electrical energy is transformed into chemical energy when the battery is being charged, and the reverse happens when the battery is discharged. A battery is formed by a set of elements or cells arranged in series. For example,

Lead acid batteries consist of two submerged lead electrodes in an electrolytic solution of water and sulfuric acid. A potential difference of about 2 volts takes place between the electrodes, depending on the instantaneous value of the charge state of the battery. The most common batteries in photovoltaic solar applications have a nominal voltage of 12 or 24 volts. A 12 V battery therefore contains 6 cells in series. The battery serves two important purposes in a photovoltaic system:

to provide electrical energy to the system when energy is not supplied by the array of solar panels, and

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to store excess energy generated by the panels whenever that energy exceeds the load.

The battery experiences a cyclical process of charging and discharging, depending on the presence or absence of sunlight. During the hours that there is sun, the array of panels produces electrical energy. The energy that is not consumed immediately it is used to charge the battery. During the hours of absence of sun, any demand of electrical energy is supplied by the battery, thereby discharging it. These cycles of charge and discharge occur whenever the energy produced by the panels does not match the energy required to support the load. When there is sufficient sun and the load is light, the batteries will charge. Obviously, the batteries will discharge at night whenever any amount of power is required. The batteries will also discharge when the irradiance is insufficient to cover the requirements of the load (due to the natural variation of climatological conditions, clouds, dust, etc.)

3.3.1 Battery Bank (A CEL Standard) -

Fig 3.8 : A 24V, 150Ah battery interconnection at CEL.

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I. Valve Regulated Lead Acid (VRLA)

Fig 3.9 : The specifications of a Valve Regulated Lead Acid Battery.

II. Rechargeable Lead Acid Tubular Positive Plate

Fig 3.10 : The specifications of Rchargeable Lead Acid Tubular Positive Plate Baettry.

3.3.2 Types of batteries

Many different battery technologies exist, and are intended for use in a variety of different applications. The most suitable type for photovoltaic applications is the stationary battery, designed to have a fixed location and

for scenarios where the power consumption is more or less irregular. "Stationary" batteries can accommodate deep discharge cycles, but they are not designed to produce high currents in brief periods of time.

Stationary batteries can use an electrolyte that is alkaline (such as Nickel-Cadmium) or acidic (such as Lead-Acid). Stationary batteries based on Nickel-Cadmium are recommended for their high reliability and resistance whenever possible. Unfortunately, they tend to be much more expensive and difficult to obtain than sealed Lead-Acid batteries.

Terminal Voltage = 12 V Capacity = 80AH

Conformance to : TEC Specifications No. TQ510 G92

Battery mounting arrangement : Not Required.

Maintenance Free.

Valve Regulated Lead Acid (VRLA)

Terminal Voltage = 6V/12V Capacity = 120 AH

Conformance to :BIS Specifications Battery Mounting Stucture

:Wooden Rack. Low Maintenance

Rechargeable Lead Acid Tubular Positive Plate

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In many cases when it is difficult to find local, good and cheap stationary batteries (importing batteries is not cheap), you will be forced to use batteries targeted to the automobile market.

Automobile batteries are not well suited for photovoltaic applications as they are designed to provide a substantial current for just few seconds (when starting then engine) rather than sustaining a low current for long period of time.

This design characteristic of car batteries (also called traction batteries) results in an shortened effective life when used in photovoltaic systems. Traction batteries can be used in small applications where low cost is the most important consideration, or when other batteries are not available.

How to differentiate? Both are basically lead acid batteries but are deesigned differently to serve differnt purposes. So the only way to differentiate between the two is by checking the ratings.

A car battery typically has two ratings:

CCA (Cold Cranking Amps) - The number of amps that the battery can produce at 32 degrees F (0 degrees C) for 30 seconds

RC (Reserve Capacity) - The number of minutes that the battery can deliver 25 amps while keeping its voltage above 10.5 volts

Typically, a deep cycle battery will have two or three times the RC of a car battery, but will

deliver one-half or three-quarters the CCAs. In addition, a deep cycle battery can withstand several hundred total discharge/recharge cycles, while a car battery is not designed to be

totally discharged. 3.3.3 Temperature effects

The ambient temperature has several important effects on the characteristics of a battery:

The nominal capacity of a battery (that the manufacturer usually gives for25°C) increases with temperature at the rate of about 1%/°C. But if the temperature is too high, the chemical reaction that takes place in the battery accelerates, which can cause the same type of oxidation that takes places during overcharging. This will obviously reduce the life expectancy of battery. This problem can be compensated partially in car batteries by using a low density of dissolution (a specific gravity of 1.25 when the battery is totally charged).

As the temperature is reduced, the useful life of the battery increases. But if the temperature is too low, you run the risk of freezing the electrolyte. The freezing temperature depends on the density of the solution, which is also related to the state of charge of the battery. The lower the density, the greater the risk of freezing. In areas of low temperatures, you should avoid deeply discharging the batteries (that is, DoDmax is effectively reduced.)

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The temperature also changes the relation between voltage and charge. It is preferable to use a regulator which adjusts the low voltage disconnect and reconnect parameters according to temperature. The temperature sensor of the regulator should be fixed to the battery using tape or some other simple method.

In hot areas it is important to keep the batteries as cool as possible. The batteries must be stored in a shaded area and never get direct sunlight. It's also desirable to place the batteries on a small support to allow air to flow under them, thus increase the cooling.

3.4 The power charge regulator

The power charge regulator is also known as charge controller, voltage regulator, charge-discharge controller or charge-discharge and load controller. The regulator sits between the array of panels, the batteries, and your equipment or loads. Significance - Remember that the voltage of a battery, although always close to 2 V per cell, varies according to its state of charge. By monitoring the voltage of the battery, the regulator prevents overcharging or over discharging. Regulators used in solar applications should be connected in series: they disconnect the array of panels from the battery to avoid overcharging, and they disconnect the battery from the load to avoid over discharging. The connection and disconnection is done by means of switches which can be of two types: electromechanical (relays) or solid state (bipolar transistor, MOSFET). Regulators should never be connected in parallel. In order to protect the battery from gasification, the switch opens the charging circuit when the voltage in the battery reaches its high voltage disconnect (HVD) or cut-off set point. The low voltage disconnect (LVD) prevents the battery from over discharging by disconnecting or shedding the load. To prevent continuous connections and disconnections the regulator will not connect back the loads until the battery reaches a low reconnect voltage (LRV). The most modern regulators are also able to automatically disconnect the panels during the night to avoid discharging of the battery. They can also periodically overcharge the battery to improve their life, and they may use a mechanism known as pulse width modulation (PWM) to prevent excessive gassing.

As the peak power operating point of the array of panels will vary with temperature and solar illumination, new regulators are capable of constantly tracking the maximum point of power of the solar array. This feature is known as maximum power point tracking (MPPT).

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Circuit implementation

Fig 3.11: Circuit diagram of a charge controller. Regulator Parameters

When selecting a regulator for your system, you should at least know the operating voltage and the maximum current that the regulator can handle.

The operating Voltage will be 12, 24, or 48 V. The maximum current must be 20% bigger than the current provided by the array of panels connected to the regulator.

Other features and data of interest include:

Specific values for LVD, LRV and HVD.

Support for temperature compensation. The voltage that indicates the state of charge of the battery vary with temperature. For that reason some regulators are able to measure the battery temperature and correct the different cut-off and reconnection values.

Instrumentation and gauges

The most common instruments measure the voltage of the panels and batteries, the state of charge (SoC) or Depth of Discharge (DoD). Some regulators include special alarms to indicate that the panels or loads have been disconnected; LVD or HVD has been reached, etc. 3.5 Converters

The regulator provides DC power at a specific voltage. Converters and inverters are used to adjust the voltage to match the requirements of your load. 3.5.1 DC/DC Converters

DC/DC converters transform a continuous voltage to another continuous voltage of a different value. There are two conversion methods which can be

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used to adapt the voltage from the batteries: linear conversion and switching conversion.

Linear conversion lowers the voltage from the batteries by converting excess

energy to heat. This method is very simple but is obviously inefficient.

Switching conversion generally uses a magnetic component to temporarily store the energy and transform it to another voltage. The resulting voltage can be greater, less than, or the inverse (negative) of the input voltage.

The efficiency of a linear regulator decreases as the difference between the input voltage and the output voltage increases. For example, if we want to convert from 12 V to 6 V, the linear regulator will have an efficiency of only 50%. A standard switching regulator has an efficiency of at least 80%.

3.5.2 DC/AC Converter or Inverter

Basic Principle: An inverter converts the DC electricity from sources such as batteries, solar panels, or fuel cells to AC electricity. The electricity can be at any required voltage; in particular it can operate AC equipment designed for mains operation.

THE GENERAL CASE

Inverters are used when your equipment requires AC power. Inverters chop and invert the DC current to generate a square wave that is later filtered to approximate a sine wave and eliminate undesired harmonics. Very few inverters actually supply a pure sine wave as output. Most models available on the market produce what is known as "modified sine wave", as their voltage output is not a pure sinusoid. When it comes to efficiency, modified sine wave inverters perform better than pure sinusoidal inverters.

A transformer allows AC power to be converted to any desired voltage, but at the same frequency. Inverters, plus rectifiers for DC, can be designed to convert from any voltage, AC or DC, to any other voltage, also AC or DC, at any desired frequency. The output power can never exceed the input power, but efficiencies can be high, with a small proportion of the power dissipated as waste heat.

Circuit description

Fig 3.12: A realization of the inverter with a transformer with a movable switch and a current source.

Auto-switching device implemented with two transistors and split winding auto-transformer in place of the mechanical switch.

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Output-

Fig 3.13 : The output achieved from the inverter with the subsequent harmonics.

Square waveform with fundamental sine wave component, 3rd harmonic and 5th harmonic.

In one simple inverter circuit, DC power is connected to a transformer through the centre tap of the primary winding.. A switch is rapidly switched back and forth to allow current to flow back to the DC source following two alternate paths through one end of the primary winding and then the other. The alternation of the direction of current in the primary winding of the transformer produces alternating current (AC) in the secondary circuit.

The electromechanical version of the switching device includes two stationary contacts and a spring supported moving contact. The spring holds the movable contact against one of the stationary contacts and an electromagnet pulls the movable contact to the opposite stationary contact. The current in the electromagnet is interrupted by the action of the switch so that the switch continually switches rapidly back and forth.

Circuit Implementation

Fig 3.14: A Single phase transistor bridge inverter

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Fig 3.15 : 500 kW, 3 phase inverter Mechanism of Inverter- An Engineers Explanation

The principal mechanism of dc-to-ac conversion consists of chopping or segmenting the dc current into specific portions, referred to as square waves, which are filtered and shaped into sinusoidal ac waveforms. Any power waveform, when analyzed from a mathematical point of view, essentially consists of the superimposition of many sinusoidal waveforms, referred to as harmonics. The first harmonic represents a pure sinusoidal waveform, which has a unit base wavelength, amplitude, and frequency of repetition over a unit of time called a cycle. Additional waveforms with higher cycles, when superimposed on the base waveform, add or subtract from the amplitude of the base sinusoidal waveform. The resulting combined base waveform and higher harmonics produce a distorted waveshape that resembles a distorted sinusoidal wave. The higher the harmonic content, the squarer the waveshape becomes. Chopped dc output, derived from the solar power, is considered to be a numerous superimposition of odd and even numbers of harmonics. To obtain a relatively clean sinusoidal output, most inverters employ electronic circuitry to filter a large number of harmonics. Filter circuits consist of specially designed inductive and capacitor circuits that trap or block certain unwanted harmonics, the energy of which is dissipated as heat. Some types of inverters, mainly of earlier design technology, make use of inductor coils to produce sinusoidal waveshapes. In general, dc-to-ac inverters are intricate electronic power conversion equipment designed to convert direct current to a single- or three-phase current that replicates the regular electrical services provided by utilities. Special electronics within inverters, in addition to converting direct current to alternating current, are designed to regulate the output voltage, frequency, and current under specified load conditions. Inverters also incorporate special electronics that allow them to automatically synchronize with other inverters when connected in parallel.

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Note-Be aware that not all the equipment will accept a modified sine wave as voltage input. Most commonly, some laser printers will not work with a modified sine wave inverter. Motors will work, but they may consume more power than if they are fed with a pure sine wave. In addition, DC power supplies tend to warm up more, and audio amplifiers can emit a buzzing sound. 3.5.3 Additional Features of the Inverters

Aside from the type of waveform, some important features of inverters include:

Reliability in the presence of surges. Inverters have two power ratings: one for continuous power, and a higher rating for peak power. They are capable of providing the peak power for a very short amount of time, as when starting a motor. The inverter should also be able to safely interrupt itself (with a circuit breaker or fuse) in the event of a short circuit, or if the requested power is too high.

Conversion efficiency. Inverters are most efficient when providing 50% to 90% of their continuous power rating. You should select an inverter that most closely matches your load requirements. The manufacturer usually provides the performance of the inverter at 70% of its nominal power.

Battery charging. Many inverters also incorporate the inverse function: the

possibility of charging batteries in the presence of an alternative source of current (grid, generator, etc). This type of inverter is known as a charger/inverter.

Automatic fall-over. Some inverters can switch automatically between different sources of power (grid, generator, solar) depending on what is available.

When using telecommunication equipment, it is best to avoid the use of DC/AC converters and feed them directly from a DC source. Most communications equipment can accept a wide range of input voltage. A special type of inverter, referred to as the grid-connected type, incorporates

synchronization circuitry that allows the production of sinusoidal waveforms in unison with the electrical service grid. When the inverter is connected to the electrical service grid, it can effectively act as an ac power generation source. Grid-type inverters used in grid-connected solar power systems are strictly regulated by utility agencies that provide net metering. Some inverters incorporate an internal ac transfer switch that is capable of accepting an output from an ac-type standby generator. In such designs, the inverters include special electronics that transfer power from the generator to the load.

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3.6 Equipment or load

It should be obvious that as power requirements increase, the expense of the photovoltaic system also increases. It is therefore critical to match the size of the

system as closely as possible to the expected load. When designing the system you must first make a realistic estimate of the maximum consumption. Once the installation is in place, the established maximum consumption must be respected in order to avoid frequent power failures. Home Appliances

The use of photovoltaic solar energy is not recommended for heat-exchange applications (electrical heating, refrigerators, toasters, etc.) Whenever possible, energy should be used sparingly using low power appliances. Here are some points to keep in mind when choosing appropriate equipment for use with a solar system:

The photovoltaic solar energy is suitable for illumination. In this case, the use of halogen light bulbs or fluorescent lamps is mandatory. Although these lamps are more expensive, they have much better energy efficiency than incandescent light bulbs. LED lamps are also a good choice as they are very efficient and are fed with DC.

It is possible to use photovoltaic power for appliances that require low and constant consumption (as in a typical case, the TV). Smaller televisions use less power than larger televisions. Also consider that a black-and-white TV consumes about half the power of a color TV.

Photovoltaic solar energy is not recommended for any application that transforms energy into heat (thermal energy). Use solar heating or butane as

alternative.

Conventional automatic washing machines will work, but you should avoid the use of any washing programs that include centrifuged water heating.

If you must use a refrigerators, it should consume as little power as possible. There are specialized refrigerators that work in DC, although their consumption can be quite high (around 1000 Wh/day).

3.7 Power Conditioning Unit

Fig 3.16: The components of a power

conditioning unit.

The Single phase Power Conditioning Unit

(PCU) provides single-phase AC power to

the specified loads.

The Power Conditioning unit mainly

comprises of MPPT, PWM Solar Charge

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Controller and a single phase inverters (02 Nos.).

The MPPT Charger is microprocessor based system designed to provide the

necessary DC/DC conversion to maximize the power from the SPV array to

charge the battery bank. The charge controller is equipped with necessary

software that allows precise charging of the battery bank. Many protection

features are also included to ensure that no abnormal or out of range charge

conditions are encountered by the battery bank. The system incorporates a

front to panel display with LEDs and a switch to indicate the "operational

status" and "fault status" of the system, reset system faults and implement

various operating modes.

The high efficiency inverter converts the DC power available from the

Array/Battery back into single phase AC, by incorporating IGBT devices for

power conversion.

During day time when the solar power is available, the charge controller

charges the battery by transferring as much as solar current to battery as

required. During this time the battery voltage is monitored continuously.

When in the night time, the solar energy is not available the system enables

the battery to deliver the current through inverter to meet the demand for

powering the street lights.

The microprocessor controlled inverter incorporates Pulse Width Modulation

(PWM) technology and incorporates all the desired safety features.

Important features/protections in the PCU:

Maximum Power Point Tracking (MPPT)

Array ground fault detection.

LCD keypad operator interface menu driven.

Automatic fault conditions reset for ali parameters like voltage, frequency

and/or black out.

MOV type surge arrestors on AC & DC terminals for over voltage protection

from lightening induced surges.

PCU operation from -5° to 55° C,

All parameters shall be accessible through an industry standard

communication link.

Over load capacity (for 30 sec.) shall be 150% of continuous rating.

Since the PCU is to be used in solar photovoltaic energy system, it shall have

high operational efficiency > 92%. The idling current at no load shall not

exceed two percent of the full load current.

In PCU, there shall be a direct current isolation provided at the output by means of a

suitable isolating transformer.

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Common Technical Specifications:

Type : Self commuted, current regulated, high frequency

IGBT base

Output Voltage Waveform : 1cp, 240VAC (±5%)

Output Frequency : Pure Sine wave: 50 Hz ±3 Hz

Continuous Rating : As per table

Nominal DC Input : 48/120 VDC

Total harmonic Distortion : <3%

Operating temp, range' : 5° to 50° C

Housing Cabinet : IP 20

Inverter Efficiency : >92%

3.8 Junction Boxes

The junction boxes shall be dust, vermin, and waterproof and made of FRP / ABS /

Thermo Plastic (iP65) must be of Hansel or any equivalent reputed make. The

terminals shall be connected to copper bus bar arrangement of proper sizes. The

junction boxes shall have suitable cable entry points fitted with cable glands of

appropriate sizes for both incoming and outgoing cables. Suitable markings shall be

provided on the bus bar for easy identification and cable ferrules shall be fitted at the

cable termination points for identification.

The junction boxes shall have suitable arrangement for the following:

Combine groups of modules into independent charging sub-arrays that shall

be wired to the controller.

Provide arrangement for disconnection for each of the groups.

Provide a test point for each sub-group for quick fault location.

To provide group array isolation.

The rating of the JB's shall be suitable with adequate safety factor to inter

connect the Solar PV array.

Metal oxide variestors shall be provided inside the Array Junction Boxes.

3.9 Wiring

An important component of the installation is the wiring, as proper wiring will ensure efficient energy transfer.

Issues specific to solar power relate to the fact that all installations are of the outdoor type, and as a result all system components, including the PV panel, support structures, wiring, raceways, junction boxes, collector boxes, and inverters must be selected and designed to withstand harsh atmospheric

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conditions and must operate under extreme temperatures, humidity, and wind turbulence and gust conditions.

Specifically, the electrical wiring must withstand, in addition to the preceding environmental adversities, degradation under constant exposure to ultraviolet radiation and heat. Factors to be taken into consideration when designing solar power wiring include the PV module’s short-circuit current (Isc) value, which represents the maximum module output when output leads are shorted.

For the electrical installation of a photovoltaic system, a distinction is made between module or string cables, the DC main cable and the AC connection cable.

The electrical connecting cables between the individual modules of a solar generator and to the generator junction box are termed 'module cables' or 'string cables'. These cables are generally used outdoors. In order to ensure earth fault and short-circuit proof cable laying, the positive and the negative poles may not be laid together in the same cable. Single-wire cables with double insulation have proven to be a practicable solution and offer high reliability.

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Fig 3.17: The cable requirements

AC connection cable

The AC connection cable links the inverter to the electricity grid via the protection equipment. In the case of three-phase inverters, the connection to the low voltage grid is made using a five-pole cable. For single-phase inverters, a three-pole cable is employed. 3.10 The Balance of System Standards

The BoS items / components of the SPV power plant must conform to the latest

edition of IEC/ equivalent BIS Standards as specified in the table.

Table 3.1: The BoS items / components with BIS Standards specifications

BoS item / component Standard Description Standard Number

Power Conditioning

Unit

Efficiency Measurements

Environmental Testing

IEC61683 and must

additionally conform to

the relevant

national/international

Electrical Safety Standards

IEC60068 2 (6, 21, 27, 30, 75, 78)

Switches / Circuit

Breakers / Connectors

General Requirements

Connectors-safety

IS/ IEC 60947 part I, II <& HI

EN 50521

Junction Boxes/

Enclosures

General Requirements IP 65 ( for outdoor) / IP/21

(for indoor)

IEC 62208

Charge

controller/MPPT unit

Design Qualification

environmental testing

IEC 62093

IEC 60068 2 (6, 21,27,30,75,78)

Storage Batteries

General requirements 4

methods of Test

Tubular Lead Acid

IEC 61427

IS 1651/IS 13369

Cobles

General Test and

Measuring methods

PVC insulated cables for

working voltages upto and

including 1100 V

-Do-, UV resistant for

outdoor installation

IEC 60189

IS 694/ IS 1554

IS /IEC 69947

Installation practice

Electrical installations of

building requirements for

SPV pow^r supply

systems

IEC 60364-7-712

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3.11 Solar Power System Configuration and Classifications

There are four types of solar power systems:

Directly connected dc solar power system

Stand-alone dc solar power system with battery backup

Stand-alone hybrid solar power system with generator and battery backup

Grid-connected solar power cogeneration system 3.11.1 Directly connected dc solar power system

As shown in Fig 3.18, the solar system configuration consists of a required number of solar photovoltaic cells, commonly referred to as PV modules, connected in series or in parallel to attain the required voltage output. Fig 3.19 shows four PV modules that have been connected in parallel. The positive output of each module is protected by an appropriate over-current device, such as a fuse. Paralleled output of the solar array is in turn connected to a dc motor via a two-pole single throw switch. In some instances, each individual PV module is also protected with a forward-biased diode connected to the positive output of individual solar panels.

Fig 3.18: A three-panel solar array diagram.

Fig 3.19: A directly connected solar power dc pump diagram.

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An appropriate surge protector connected between the positive and negative supply provides protection against lightning surges, which could damage the solar array system components. In order to provide equipment-grounding bias, the chassis or enclosures of all PV modules and the dc motor pump are tied together by means of grounding clamps. The system ground is in turn connected to an appropriate grounding rod. All PV interconnecting wires are sized and the proper type selected to prevent power losses caused by a number of factors, such as exposure to the sun, excessive wire resistance, and additional requirements that are mandated by the IEC.

The photovoltaic solar system described is typically used as an agricultural application, where either regular electrical service is unavailable or the cost is prohibitive. A floating or submersible dc pump connected to a dc PV array can provide a constant stream of well water that can be accumulated in a reservoir for farm or agricultural use. In subsequent sections we will discuss the specifications and use of all system components used in solar power cogeneration applications.

3.11.2 Stand-alone dc solar power system with BATTERY BACKUP

The solar power photovoltaic array configuration shown in Fig, a dc system with battery backup, is essentially the same as the one without the battery except that there are a few additional components that are required to provide battery charge stability.

Fig 3.20 : Battery-backed solar power–driven dc pump.

Stand-alone PV system arrays are connected in series to obtain the desired dc voltage, such as 12, 24, or 48 V; outputs of that are in turn connected to a dc collector panel equipped with specially rated over current devices, such as ceramic-type fuses.

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The positive lead of each PV array conductor is connected to a dedicated fuse, and the negative lead is connected to a common neutral bus. All fuses as well are connected to a common positive bus. The output of the dc collector bus, which represents the collective amperes and voltages of the overall array group, is connected to a dc charge controller, which regulates the current output and prevents the voltage level from exceeding the maximum needed for charging the batteries.

The output of the charge controller is connected to the battery bank by means

of a dual dc cutoff disconnect. As depicted in Fig 3.20, the cutoff switch, when turned off for safety measures, disconnects the load and the PV arrays simultaneously.

Under normal operation, during the daytime when there is adequate solar

insolation, the load is supplied with dc power while simultaneously charging the battery. When sizing the solar power system, take into account that the dc power output from the PV arrays should be adequate to sustain the connected load and the battery trickle charge requirements.

Battery storage sizing depends on a number of factors, such as the duration of

an uninterrupted power supply to the load when the solar power system is inoperative, which occurs at nighttime or during cloudy days. Note that battery banks inherently, when in operation, produce a 20 to 30 percent power loss due to heat, which also must be taken into consideration.

When designing a solar power system with a battery backup, the designer must determine the appropriate location for the battery racks and room ventilation, to allow for dissipation of the hydrogen gas generated during the charging process. Sealed-type batteries do not require special ventilation.

All dc wiring calculations discussed take into consideration losses resulting

from solar exposure, battery cable current derating, and equipment current resistance requirements.

3.11.3 Stand-alone hybrid AC SOLAR POWER SYSTEM with generator and battery backup

A stand-alone hybrid solar power configuration is essentially identical to the dc solar power system just discussed, except that it incorporates two additional components, as shown in Fig 3.11.4. The first component is an inverter. Inverters are electronic power equipment designed to convert direct current into alternating current. The second component is a standby emergency dc generator.

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Fig 3.21 : Stand-alone hybrid solar power system with standby generator.

3.11.4 Grid-connected solar power COGENERATION SYSTEM

With reference to Fig 3.11.5, a connected solar power system diagram, the power cogeneration system configuration is similar to the hybrid system just described. The essence of a grid-connected system is net metering. Standard service meters are

odometer-type counting wheels that record power consumption at a service point by means of a rotating disc, which is connected to the counting mechanism. The rotating discs operate by an electro physical principle called eddy current, which consists of voltage and current measurement sensing coils that generate a proportional power measurement. New electric meters make use of digital electronic technology that registers power measurement by solid-state current- and voltage-sensing devices that convert analog

measured values into binary values that are displayed on the meter bezels by liquid crystal display (LCD) readouts. In general, conventional meters only display power consumption; that is, the meter counting mechanism is unidirectional.

Net metering The essential difference between a grid-connected system and a stand-alone system is that inverters, which are connected to the main electrical service, must have an inherent line frequency synchronization capability to deliver the excess power to the grid. Net meters, unlike conventional meters, have a capability to record consumed or generated power in an exclusive summation format; that is, the recorded power registration is the net amount of power consumed—the total power used minus the amount of power that is produced by the solar power cogeneration system. Net meters are supplied

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Figure 3.22 : Grid-connected hybrid solar power system with standby generator.

and installed by utility companies that provide grid-connection service systems. Net metered solar power co-generators are subject to specific contractual agreements and are subsidized by state and municipal governmental agencies. When designing net metering solar power cogeneration systems, the solar power designers and their clients must familiarize themselves with the rebate fund requirements. Essential to any solar power implementation is the preliminary design and economic feasibility study needed for project cost justification and return on-investment analysis.

Grid-connection isolation transformer In order to prevent spurious noise transfer from the grid to the solar power system electronics, a delta-y isolation transformer is placed between the main service switchgear disconnects and the inverters. The delta winding of the isolation transformer, which is connected to the service bus, circulates noise harmonics in the winding and dissipates the energy as heat. Isolation transformers are also used to convert or match the inverter output voltages to the grid. Most often, in commercial installations, inverter output voltages range from 208 to 230 V (three phase), which must be connected to an electric service grid that supplies 277/480 V power. Some inverter manufacturers incorporate output isolation transformers as an integral part of the inverter system, which eliminates the use of external transformation and ensures noise isolation.

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DESIGN

Design of a solar PV system is the process of estimation of load, sizing of the

batteries and sizing of the solar modules that are used in the PV system.

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4.1 Introduction and basic principles

The function of a PV system is to power electrical loads .The loads maybe AC loads

or DC loads. The solar array produces DC power only during sunshine hours. So if

the loads are to be powered during non-sunshine hours energy storage devices are

required. Lead acid batteries and Nickel cadmium batteries serve this purpose. To

feed the AC loads an inverter is required. Also auxiliary power sources such as

diesel generator, wind generator or by connecting the PV system to the grid.

Accordingly, PV systems maybe:

(a) Stand-alone PV systems

(b) Grid-connected PV systems

(c) Hybrid PV systems

As explained in the second chapter a stand-alone system is the one which is not

connected to the power grid. In contrast, the PV systems connected to the grid are

called grid-connected PV systems. Hybrid PV systems could be stand-alone or grid-

connected type, but have at least one more source other than the PV.

Fig 4.1 India’s first two

megawatt grid connected

project, commissioned in the

state of West Bengal in east

India.

Source: pv-magazine.com

Some of the basic Principles to Follow When Designing a Quality PV System

i. A packaged system should be selected that meets the owner's needs.

Customer criteria for a system may include reduction in monthly electricity

bill, environmental benefits, desire for backup power, initial budget

constraints, etc. The PV array should be sized and oriented to provide the

expected electrical power and energy.

ii. It should be ensured that the roof area or other installation site is capable of

handling the desired system size.

iii. Sunlight and weather resistant materials for all outdoor equipment should be

specified.

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iv. Array should be located to minimize shading from foliage, vent pipes, and

adjacent structures.

v. System should be designed in compliance with all applicable building and

electrical codes.

vi. The system should be designed with a minimum of electrical losses due to

wiring, fuses, switches, and inverters.

vii. The battery system should be properly housed and managed, should batteries

be required.

viii. It should be ensured that the design meets local utility interconnection

requirements.

PV systems are designed and sized to meet a given load requirement. PV system

sizing and design involves:

1. PV system design involves a decision on which configuration is to be adopted

to meet the load requirement as explained above.

2. Once the system configuration is decided the size or capacity of the various

components is determined.

POINTS TO KEPT IN MIND

i. One has to first decide whether to use a particular component at all,

particularly the performance enhancing components like the charge

controllers and MPPT circuits. As these circuits themselves consume energy

and add to the overall system cost, one must determine whether their use

would really result in energy saving. Thus, one has to judiciously optimize

the system performance and cost.

ii. A decision also has to be taken involving the quality of each component from

the consideration of initial cost, its performance, and life of the component. A

low quality component (charge controller, for instance) may be cheaper

initially but probably will be less efficient and may not last longer. On the

other hand, a relatively expensive but higher quality component is more

likely to perform better (saving energy and thus cost) and may be able to

recover its cost in the long run.

A PV system design and sizing process passes through the following two stages

depending on the level of details used in components sizing:

Approximate design

Precise design

In the approximate design, several simplifying assumptions are made with respect

to the component performance (without referring to the actual data sheets), solar

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radiation data, seasonal variation in the load performance variation of PV panel with

season, etc. In the precise design, however, attention is given to accurate details of all

the above factors.

4.2 System type selection

One has to determine the configuration of PV system and which components (PV

panels, load, battery, controllers, diesel generator, etc.) are to be connected in a

system. The configuration and design of the system will change depending on

1. The type of the load (AC or DC, light or heavy, etc.),

2. The load requirement (critical/non-critical, reliability, cost, etc.)

3. Its geographical location (wind resources, solar resources, proximity with

grid, etc.).

A solar PV system configuration can be very simple, incorporating only two

components (load and the PV panel), or it can be very complex, containing several

power sources, sophisticated controllers and multiple energy storage units to meet

stringent load requirements. In the previous chapter the various configurations of a

PV system are explained. The establishment or household owner has to choose from

these configurations while keeping in mind the following parameters

Load requirements

Resource availability

Performance of the system

Reliability of the system

Cost of the system

4.3 Home Appliances

The use of photovoltaic solar energy is not recommended for heat-exchange applications (electrical heating, refrigerators, toasters, etc.) whenever possible, energy should be used sparingly using low power appliances.

Fig 4.2Some of the appliances which can be run by solar PV system

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Here are some points to keep in mind when choosing appropriate equipment for use with a solar system:

i. The photovoltaic solar energy is suitable for illumination. In this case, the use of halogen light bulbs or fluorescent lamps is mandatory. Although these lamps are more expensive, they have much better energy efficiency than incandescent light bulbs. LED lamps are also a good choice as they are very efficient and are fed with DC.

ii. It is possible to use photovoltaic power for appliances that require low

and constant consumption (as in a typical case, the TV). Smaller televisions use less power than larger televisions. Also consider that a black-and-white TV consumes about half the power of a colour TV.

iii. Photovoltaic solar energy is not recommended for any application that

transforms energy into heat (thermal energy). Use solar heating or butane as alternative.

iv. Conventional automatic washing machines will work, but one should

avoid the use of any washing programs that include centrifuged water heating.

v. If one must use a refrigerator, it should consume as little power as

possible. There are specialized refrigerators that work in DC, although their consumption can be quite high (around 1000 Wh/day).

The estimation of total consumption is a fundamental step in sizing the solar system. Here is a table that gives a general idea of the power consumption that one can expect from different appliances. Table 4.1 Power rating of some home appliances

Appliances Power Rating

(Watt)

Tube-light 40

CFL 7-28

Ceiling Fan 55-85

Wall Fan 65-100

Laptop 80-100

Television 150-250

Personal Computer 250-300

Printer 300-500

Projector 1000-3000

Water Pump 350-3500

Air Conditioning System 1000-5000

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4.4 Illustration and Flowchart for design of habitat PV system

Flowchart 4.1

SCHEMA ‘A’Illustration and Flowchart for Design of Habitat PV System

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%

En

ergy

nee

ds

to b

e st

ored

= L

oad

est

imat

ed ×

% o

f en

ergy

bac

k u

p

Bat

tery

Eff

icie

ncy

Bat

tery

Vol

tage

=

12

V2.

764

kW

h

4.18

8 k

Wh

7.53

9 k

Wh

Bat

tery

Am

per

e-H

our

Cap

acit

y =

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ergy

nee

d t

o b

e S

tore

d(k

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atte

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ctu

al B

atte

ry

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4.61

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6.98

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h

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hts

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ht

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ud

y d

ay

(wor

st c

ase)

90

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p

Tot

al d

aily

el

ectr

icit

y d

eman

d

(Wh

) =

640

8

Tot

al d

aily

el

ectr

icit

y d

eman

d

(kW

h)

= 6

.408

Loa

d e

stim

ated

=

7.12

Est

imat

e d

aily

el

ectr

ical

en

ergy

re

qu

ired

Loa

d i

s su

bje

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to

chan

ge

wit

h c

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n-

P

ower

Rat

ing

of a

pp

lian

ce

Dai

ly u

sage

hou

rs

No.

of

un

its

Sel

ect

inve

rter

w

ith

rat

ing

slig

htl

y gr

eate

r th

an t

otal

dai

ly

load

(1k

W)

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rter

E

ffic

ien

cy ≥

90%

(9

0-95

%)

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ergy

to

load

& i

nve

rter

=

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aily

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d(k

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) In

vert

er E

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cy(%

)

p

AB

Fin

d o

ut

the

ann

ual

G

SR

* in

you

r h

abit

at

area

(5.7

8hrs

, Hyd

erab

ad)

GS

R*

- G

lob

al S

olar

Rad

iati

on

Est

imat

ion

of

PV

mod

ule

s re

qu

ired

En

ergy

nee

ded

du

rin

g th

e d

ay =

7.

12k

Wh

Tot

al S

yste

m E

ffic

ien

cy (

TS

E)

=

80%

PV

pan

el O

per

atin

g P

erfo

rman

ce (

OP

)= 8

5%

Act

ual

PV

Siz

e =

En

ergy

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ded

du

rin

g D

ay

An

nu

al G

SR

× P

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P ×

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7.12

kW

h

0.8×

0.85

×5.

78h

1.81

2 k

W

p

C

Part A of the flowchart refers to load estimation, part B refers to sizing of batter and

141

part C refers to sizing of PV modules. These processes are explained in detail in the

following topics.

5.7 Design process

The process is explained with the help of an example.

A solar PV system is to be designed wherein the load consists of a CFL, TV, fan, and

refrigerator and computer. The system should allow the use of loads in the non-

sunshine hours. The operating hours and the power rating of these loads are

Table 4.2 illustrative habitat appliance use in a day

The formulae for calculations are marked in REDand the calculations done for the

solar PV system to be designed is marked in BLUE.

5.7.1 Load estimation

In this step the energy required for the operation of the load is determined. While

estimating the load the following parameters are considered:

Type of load, DC or AC (most of the appliances use AC power);

Number of loads (e.g. Lighting, cooling, TV etc.)

Power voltage and current ratings of each load

Hours of load operation per day

Energy required per day by the load and

Efficiency of the power converter

As done in the table 4.3:

The power rating (W) is to be multiplied with the no. of hours of operation of all the

loads and then it is all added up to find the total daily energy consumption.

Table 4.3: Calculation of

load in Watt-hr

Separate tables can be

made for AC and DC

loads. But when the

calculation is done the both

total energy of both the

Load Watts H/day Number

CFL 9 5 2

Fan 60 8 1

TV(21”) 150 2 1

Refrigerator 150 8 1

Computer 250 3 1

Load Watts H/day Number Watt-hr.

CFL 9 5 2 90

Fan 60 8 1 480

TV(21”) 150 2 1 300

Refrigerator 150 8 1 1200

Computer 250 3 1 750

Total daily Watt-hr/day 2820

142

loads is to be considered. In this example however we have considered a house with

only AC loads.

It is important to keep in mind that the system should be designed for the worst case

scenario, energy required changes from day to day and season to season basis. The

system should meet the peak energy requirement or the peak load demand i.e. the

highest requirement in a particular day of the year. However a reliable system

design will add to the cost of the system. Thus a balance has to be struck between

reliability and cost.

5.7.2 Inverter rating

As explained in the previous chapter an inverter supplies power to AC loads and

converter supplies power to DC loads. The inverter and converter should be capable

of handling input current from the battery and output current to the load.

In the example since there are only AC loads only inverters are used. Generally,

input voltage varies from 12 - 72V and current from 1 – 10’s of Amperes. The output

is fixed at 220V 60Hz.

In this step the inverter rating is calculated. For this:

The sum of all the loads connected to the inverter is taken

Table 4.4: Iillustrative power (watt)use per day

5.7.3 Daily energy supplied by the inverter

Load energy is supplied to the load from the battery through the inverter. The

inverter is not 100per cent efficient it ranges from 90 – 97per cent. Thus the energy

supplied by inverter is more than the total load requirement as calculated in the first

step.

Energy supplied by the inverter = Load energy requirement/ Efficiency of inverter

In this case inverter with 93per cent efficiency is taken

Energy supplied by inverter= 2820/0.93 = 3032.25 Wh.

5.7.4 System voltage

System voltage is defined as the input voltage to the inverter. It depends on the

battery voltage, line current, allowable voltage drop, power loss in the cables, etc.

Load Watts Number Total Watts

CFL 9 2 18

Fan 60 1 60

TV(21”) 150 1 150

Refrigerator 150 1 150

Computer 250 1 250

628

143

Typically terminal voltage of batteries are 12V, therefore system voltage are

generally multiples of 12, 24, 36, 48Vetc.

High system voltage results in less power loss and voltage drop in cables. But high

system voltage also means more PV panels in series and therefore high cost. So

system voltage should be chosen after careful considerations.

In this case, a system voltage of 24V is chosen

5.7.5 Battery capacity

3032.25 Wh of energy is required to be supplied by the battery and the terminal

voltage of the battery bank should be 24 V. The parameters to be considered in sizing

of batteries are:

Depth of discharge (DoD) of battery;

Voltage and ampere-hour (Ah) capacity of the battery; and

Number of days of autonomy.

For PV applications deep discharge batteries are used with DoD in the range of 60%

to 80% and batteries of capacities 25Ah, 50Ah, 100Ah, 150Ah are available.

In this case batteries of 12V 100Ah with DoD 70% are chosen

1. Usable capacity = Rated capacity x DoD

Therefore, Usable capacity = 100 x 0.7 = 70Ah

2. Now, Required charge capacity = energy that needs to be supplied by the

battery/ system voltage

The energy that needs to be supplied by the battery = 3032.25 Wh

The system voltage = 24 V

Therefore, the required charge capacity = 3032.5/24= 126.3Ah

3. The total no. of batteries required = Required charge capacity/ Usable

capacity

= 126.3/ 70 = 1.8

This can be rounded off to 2 batteries.

Now because of this round off, some extra charge capacity (140 Ah instead of 126.3

Ah required) is available to the load. These two batteries should be connected in

parallel. But 100 Ah batteries is of 12 V only, so the battery bank needs to supply the

charge at 24 V (system voltage). Therefore in order to get 24 V, two 12 V batteries

should be connected in series to get 24 V terminal voltage.

144

Thus, in total there will be four batteries of 100Ah capacity in the

battery bank, two of them connected in series and two such series

connected batteries are connected in parallel.

5.7.6 Consider for battery autonomy

The PV system is should be designed for some autonomy during the completely

cloudy conditions. The autonomy is defined as the number of days the battery

should be able to supply the energy to load even when for those number of days

there is no sunshine (assuming on completely cloudy days, no energy is generated

by PV panels). , 2 days’ autonomy means the battery bank should be able to supply

the energy to the load where there is no sunshine for 2 days. Thus, depending on the

number of days of autonomy, the battery bank size should be increased.

If total daily Ah requirement is X and the number of days of autonomy is n days,

then total Ah required including autonomy is given as:

Total Ah = X + n xX

Therefore, total Ah = 126.3 + 2 x126.3 = 378.9 Ah

Thus, in this example, battery bank size should be three times than what was

derived previously.

Now instead of 4 batteries of 12 V, 100 Ah, we would require

4 x 3 = 12 batteries of 12 V and 100 Ah.

As the autonomy day increases, the battery bank size increases adding to the cost.

Normally, high autonomy is required for the PV system requiring high reliability

such as in medical applications, defence applications, etc. Convenient number of

autonomy days should be chosen keeping in mind the cost of the system. Typically,

the battery cost is about 30% of the overall PV system cost.

Fig 4.3Series and

parallel connection of

batteries to supply

the required energy

to the load

considering 2 days’

autonomy

5.7.7 Daily energy

generated by panels

145

The parameters of concern for the PV module sizing are:

Voltage, current and wattage of the module;

Solar radiation at a given location and at given time;

Efficiency of the batteries;

Temperature of the module;

Efficiency of the MPPT and charge controller unit; and

Dust level in working environment.

The PV panels are required to supply energy to battery which is consumed daily but

not the total energy stored in the battery bank. The energy taken out from the battery

bank is the energy required by the load on daily basis. The energy supplied by the

panels will be higher because the efficiency of the charge discharge cycle of the

battery is less than 100%. It is 80 – 90%.

An efficiency of 85% is taken in this case.

The energy supplied at the input of battery terminal = Energy supplied by the

battery/ Battery efficiency

= 3032.25/0.85

= 3567.3Wh

The energy to the input terminal of the battery bank is supplied through controller

electronics (charge controller and MPPT, refer). The efficiency of the controller

circuit is generally quite high.

A controller circuit efficiency of 90% is assumed.

The energy that should be supplied by the PV panels at the input of controller circuit

= Energy supplied at the input of battery terminal/Controller circuit efficiency

= 3567.3/0.9= 3963.7Wh

Thus, about 3963.7Wh energy should be generated by PV panels every day.

5.7.8 Solar radiation, capacity and number of panels

Total Ah generated by PV panels = Energy supplied by PV panels/ System voltage

= 3963.7/24= 165.1 Ah

During a day, from sunrise to sunset, the solar radiation intensities vary

significantly. Normally, the number of daily sunshine hours equivalent to 1000

W/m2 (equivalent peak sunshine hours) is estimated for the location at which PV

system needs to be installed In India, the peak equivalent sunshine hours vary

between 5 h and 7 h, corresponding to 5000 Wh/m2 and 7000 Wh/m2-day.

146

For this example, there is 6HRS equivalent peak sunshine hours in the location

where solar PV system needs to be installed.

Total amperes to be produced = Total Ah generated by PV panels/no. of peak

sunshine hours

= 165.1/6

= 27.5A

Peak power rating is the maximum power the module will produce under 1000

W/m2 and at 25 °C. A typical peak power rating of modules varies from 5 Wp to 300

Wp.

PV module of peak power rating 75 Wpis taken in this example. The manufacturer’s

datasheet provides the current and voltage of the module at maximum power point,

the rated Wp of module. The typical value of voltage and current of 75 Wp module at

maximum power point (Vmand Im) would be about 15 V and 5 A, respectively.

No. of modules required = Total amperes to be produced/ Imof module

= 27.5/5

= 5.5

On rounding off 6 modules of 75 Wp are required to provide 27.5 A current.

Two modules should be put in series to get voltage higher than 24 V (system

voltage), required for charging the batteries. Thus, overall 6x2= 12 PV modules of 75

Wpis required, each row containing two modules in series and there would be six

such rows in parallel.

The interconnection of PV modules is shown.

Fig 4.4 Series and parallel connection of PV modules with their ratings that are

required to supply the energy to the load.

This completes the design of the PV systemof a solar PV system wherein the load

consists of a CFL, TV, fan, and refrigerator and computer.

147

Fig 4.5Complete design of solar PV system to fulfil the required load as described in

theexample

4.6 Wire sizing

In solar PV system appropriate dimensions (diameter and length) of the wires or

cables for interconnection of modules, batteries and loads should be used. The size

of the wire should be chosen to avoid excessive voltage drops in a line (wire or cable

connecting two points electrically). Normally, the voltage drop in the line connecting

modules to batteries should not be more than 5% of the line voltage. Also, it should

be ensured that the maximum current passing through the cables should be within

the current handling capacity of the cables.

The voltage drop for a given cable of specified material resistivity (ρ), length (L) and

cross sectional area (A) can be estimated as:

Vd= 2 x ∆V = 2 x I x ρ L

A

The factor of “2” in the above equation is introduced due to the fact that the length

of the cable used is actually double (for taking current to and fro) the physical

distance between PV module and the battery or the battery and the load.

The Vd should be within 5% limit of the line voltage, i.e., if the line

voltage is 12V, the voltage drop should not be more than 0.6V

148

Typically, the diameter of the cables used in DC electric system is higher than the

diameter of cables used in AC electrical systems. In the solar PV systems, the DC

voltage levels are normally in range of 12V to 48V (as against 220V in AC systems).

Due to this, the loads of similar power rating need to be supplied with higher

current in DC systems as compared to AC systems. If the cable of the same diameter

(same length and material as well) is used in both AC and DC systems, the voltage

drop in the DC system would be 18.5 times more than the AC system as per the

above equation. Therefore, to limit the voltage drop in DC system, cables of larger

diameter are used.

5.8 Factors affecting performance of a PV system

a. Shadow free area

Shading of a module can dramatically reduce the output from the whole array. Shading should therefore always be avoided, especially from any trees or buildings to the South of the array. PV modules are very sensitive to shading. Shading obstructions can be defined as soft or hard sources. If a tree branch, roof vent, chimney or other item is shading from a distance, the shadow is diffuse or dispersed. These soft sources significantly reduce the amount of light reaching the cell(s) of a module. Hard sources are defined as those that stop light from reaching the cell(s), such as a blanket, tree branch, bird dropping, or the like, sitting directly on top of the glass. If even one full cell is hard shaded the voltage of that module will drop to half of its unshaded value in order to protect itself. If enough cells are hard shaded, the module will not convert any energy and will, in fact, become a tiny drain of energy on the entire system.

Shadow free area implies the area which is completely available for sunshine

throughout the day. Panels should be fitted in a shadow free area such that sunlight

falls on the panel all day long. Preferably the roof should be a RCC permanent

structure with strength of more than 150 Kg/m2.

Approximately 1Kilo watt system requires a shadow free area of nearly 15 m2 i.e.,

150 Square Feet.

b. Orientation

Orientation of panels/array depends on your latitude and where the house or

establishment is. If it's in the northern hemisphere, it faces south, with a tilt direction

at the sun with respect to the average tilt of the earth.

149

To capture the maximum amount of solar radiation over a year, the solar

array should be tilted at an angle approximately equal to a site's latitude, and facing

within 15° of due south. To optimize winter performance, the solar array can be

tilted 15° more than the latitude angle, and to optimize summer performance, 15°

less than the latitude angle. At any given instant, the array will output maximum

available power when pointed directly at the sun.

To get the most from solar panels, it has to be pointed in the direction that captures

the most sun. Solar panels should always face south, since India is located in the

northern hemisphere.

Fig 4.6 Sun’s path during

summer and winter

When installing photovoltaic

modules, it is important to

keep in mind that they

generate maximum power

when facing the sun directly.

The fixed position which

approximates this ideally

over the course of the year,

thus maximizing annual

energy production at the

angle listed in the table in the next column.

Table 4.5: Tilt angle as per geographic latitude

Latitude Site Tilt Angle

0-15 15º

15-25 SAME AS Latitude

25-30 add 5° to local latitude

30-35 add 10° to local latitude

35-40 add 15° to local latitude

40+ add 20° to local latitude

c. Obstacle handling

Panels location should be such that it is away from the shadow zone of the obstacle

(three times the height if obstacle is in east and the one time height of obstacle if

obstacle is in south) from the panel level.

150

d. Temperature

In a solar cell, the parameter most affected by an increase in temperature is the open-

circuit voltage. The impact of increasing temperature is shown in the figure below.

Fig4.7 The effect of temperature on

the IV characteristics of a solar cell.

Thus, Module output power

reduces as module temperature

increases. When operating on a roof,

a solar module will heat up

substantially, reaching inner

temperatures of 50-75 oC.

For crystalline modules, a typical temperature reduction factor is around 89% or

0.89. So the “100-watt” module will typically operate at about 85 Watts (100 Watts x

0.89 = 89 Watts) in the middle of a spring or fall day, under full sunlight conditions.

e. Dirt and dust

Dirt and dust can accumulate on the solar module surface, blocking some of the sunlight and reducing output. Although typical dirt and dust is cleaned off during every rainy season, it is more realistic to estimate system output taking into account the reduction due to dust buildup in the dry season.

Fig 4.8 Solar panels with dirt and dust settled on it

A typical annual dust reduction factor to use is 93% or 0.93. So the “100watt module,” operating with some accumulated dust may operate on average at about 93 Watts (100 Watts x 0.93 = 93

Watts).

151

INSTALLATION AND

COMMISSIONING

Installation is the process of setting up the solar modules on different

mounting structures and connecting them to the battery and PCU for production

of electricity.

System commissioning is the process of checking and testing the

installation and putting it into service.

152

153

Self initiative by using “Reference Handbook”

Habitat owner seek help of a qualified person or by self can design the SPV system

System DesignSolar subsidy from Govt.

Detailed estimates

Installation process

Design Drawings, Site area plan,

electrical schematics

Place order at CEL

Procure from market

Installation and inspection

Detailed list of components

Reach out to manufacturers

How Habitat owner can install SPV

system?

How to start SPV system in Habitat?

Calculate solar insolation

Habitat site measurements

Analyze shadow free area

Estimate load

System requirement

Estimate project cost and future energy savings

Reference Handbook& do it yourself giude

The habitat owner will have understanding of technologies the long run achievements contribution to nature economic benefit

sustainable habitat ecosystem

Place order to other nearest installer

SCHEMA ‘B’Flowchart to start with installation of Habitat

PV System

Go to

Schema ‘A’

The above flowchart 5.1 gives an overview of the entire process of installation of

solar panels to be borne in mind by the user for a well implemented installation.

154

5. INSTALLATION

Before the commencement of the installation it is important to get familiarized

with the manufacturer’s instructions supplied with each of the components. The

site visit will allow identification of mounting positions for each item. It is

helpful to draw a wiring diagram before starting the installation. The installation

has no correct order for of the various system components, except for the

eventual connection and commissioning.

5.1 Safety

At all times during the

installation, the safety of the

installers and public must be

paramount. The public

should be kept away from

the installation site at all

times, by the use of barriers

or fencing where necessary.

Particular attention should

be paid to the safety of

children.

5.1.1 Electrical

Although Solar power systems are generally low

voltage, but the wiring regulations for the country of

installation should always be observed. The following

should be kept in mind:

Inverter output is mains voltage AC and can be lethal. It should be treated as

any other mains supply.

Solar arrays generate electricity when exposed to the sun, whether connected

to control equipment or not. The solar array output cables should be treated

as live and solar array should be covered when connections are being

made.

The open circuit voltage of a solar array is significantly greater than the

system voltage. For example a 48 Volt array can have an open circuit voltage

of nearly 90 Volts, can be lethal to children, the elderly or anyone with a

heart condition.

155

Batteries can produce currents of hundreds or even thousands of amps

giving rise to the risk of fire. Great care should be taken to protect the battery

terminals from shorting by tools and all jewellery should be removed.

If in any doubt about your abilities, or if required by local regulations, then a

qualified electrician must be employed.

5.1.2 Chemical

Lead acid batteries contain dilute sulphuric

acid and liberate hydrogen when charging.

The following precautions should be

observed:

1. Great care should be taken when

filling batteries with electrolyte; suitable

protective clothing should be worn including

eye protection and it should be carried out in

a well ventilated area, preferably outdoors.

2. Great care should be taken to prevent arcing near battery terminals as

explosion may result.

5.1.3 Handling

Batteries and solar arrays present certain hazards in handling as follows:

1. Lead acid batteries are extremely heavy. Appropriate lifting gear should

be used.

2. Most solar panels are made from glass and should be treated as fragile.

3. Installation of solar arrays may involve working at height .All necessary

precautions must be observed and the services of a qualified rigger or

roofer should be employed if necessary.

FOR SAFE INSTALLATION WORK

WARNING

• Mounting System should not be cut or modified. Doing so is dangerous. Safety cannot be guaranteed.

• Work should not be done during stormy weather. Solar modules can be caught in the wind, causing accidents.

156

CAUTION

i. One should never step or sit on the glass surface of a solar module. The

glass may break, resulting in shock or bodily injury. The module may also

stop generating power.

ii. The supplied parts should always be used to attach the solar modules and

mounts. Use of weaker parts, such as screws that are too short, is

dangerous and may cause the solar modules or mounts to fall.

iii. The specified tools should only be used. The solar modules or mounts

may fall if the installation is not strong enough, for example when parts

are not tightened sufficiently.

iv. Regardless of whether one is working on a new or existing roof, the

sheathing should never be allowed to become wet. The sheathing should

be protected from rain during the installation. Failure to do so may cause

leaks.

v. Only the specified materials should be used. Use of other materials is

dangerous. Materials other than specified can reduce performance and

can cause leaks, shock, and so on.

vi. Parts should not be cut or modified.

vii. Protective earth grounding of the individual photovoltaic modules should

be achieved by securing the modules to the mounting frames. The

assembly instructions should be closely followed, in order to ensure a

reliable ground connection.

Artificially concentrated sunlight shall not be directed on the module.

Wiring methods should be in accordance with the NEC.

Wires and cables should be installed with appropriate hardware in

accordance with applicable electrical codes.

The framing system shall be grounded in accordance with NEC.

All of the Rails in an installation shall be provided with protective earth

bonding wires when installed.

Systems should not be located near coastal locations or other saltwater

locations. Minimum distance is 0.3 miles from the body of water.

Systems should also not be located in a corrosion prone area.

Holes should not be drilled in the frame.

Work should be done under dry conditions with dry tools.

Installation should not be near flammable gases.

Solar module should be completely covered with opaque materials when

wiring to halt production of electricity.

The backside of solar module surfaces should be kept free of foreign objects.

157

Chemicals should not be used on solar modules when cleaning.

Cable electrical contacts should not be touched.

Solar modules should not be exposed to sunlight that is concentrated with

mirrors, lenses, or similar means.

Local codes should be consulted and other applicable laws and statutes

concerning required permits and regulations concerning installation and

inspection requirements. Solar modules should be installed according to

applicable codes.

Shadowing of cells should be avoided in order to prevent solar module hot

spots and/or reduction in power.

PV MODULES

Points to check before wiring.

1. The solar modules generate electricity when exposed to light, thus

insulating gloves should be worn..

2. A multi-meter for volts, amps, resistance, and continuity capable of

measuring DC and AC up to 600V and 40A is needed.

3. All tools being used should be insulated.

• Wiring work should be performed according to the provisions of the National Electrical Code. The grounding work and wiring connections to the inverter should be performed by a qualified electrician.

WARNING

• Adhere to all NEC. The solar array generates electricity whenever it is exposed to sunlight. One should be careful when handling it as there is a danger of shock.

WARNING

158

Wiring the solar modules.

i. During the installation of the modules on the mount, an output cable

should never be allowed to become caught between the mount and a

module frame.

ii. The solar modules generate electricity when exposed to sunlight; care

should be taken to not short circuit the output cables. The cables can

become overheated and their cable sheaths can melt.

iii. It should be ensured the module connectors are fully inserted. There is a

risk of malfunction if they are not pushed in all the way.

iv. The output cables should be supported so that there is no slack. High

winds can blow slack cable against the mount, damaging the cables.

Wiring from solar arrays to the inverter (connector box).

i. The provisions of the National Electrical Code should be adhered to.

ii. For wiring through walls, the cables should be protected with metal

conduits, flexible metal conduits, or other protection. Failure to do so can

result in shock and short circuits. Conduit should always be used to protect

sections of array output cables that are exposed to sunlight. For outdoor

wiring, Cables should be protected with PVC conduits, metal conduits or

flexible conduits.

iii. Water should be prevented from entering or building up in conduit by using

waterproof or duct seal.

iv. To prevent shock, the cut ends of array output extension cables should be

taped and labeled (the side opposite to the connector side) before connecting

to solar module output cables. Further, they should be taped again after

measurement of the voltage of each array.

v. To prevent shock when the array output cables are being connected to the

inverter, tape should be removed from one cable at a time as the cables are

being connected.

Measuring array output voltage

i. It should be ensured that all solar modules are exposed to direct sunlight.

(Lightproof sheets should be removed, if present.)

ii. The volt meter measurement range should be set to a DC voltage, greater

than the expected measurement (for example 600 VDC).

iii. The plus (+) solar array output cables should be kept away from the ends of

the minus (-) cables. Dangerous arcs can occur. (The array output voltage

under normal conditions <clear skies> can be very high.)

159

Grounding the mount

To prevent shock, a ground wire should always be connected from the mounting

hardware to earth.

POINTS TO CHECK WHEN SELECTING THE INSTALLATION LOCATION

The following should be checked before starting installation work.

a) Condition of the house where solar power system is to be installed

Inspection of roof structure

It is important to inspect the structural integrity of the roof and the durability of

the roof materials. The mounting structure and solar modules require a strong

base for durable and reliable operation in local environments. A safety harness

should always be worn when working on the roof. Inspection of the roof surface

in the area of the installation should be carried out for cracks, water leakage, and

roofing material quality and uniformity. This is especially important if the roof is

older than10 years. The roof should also be inspected for sags and other

abnormalities. A sag or deep depression in the roof may indicate a structural

weakness in the support system that may require correction.

Fig5.1 Examples of poor roof condition

Inspection of the roof support system

All rafters, trusses and other materials

should be in good condition. Inspection

should be carried out for indication of

previous water leaks. The spacing of the

rafters or trusses should be measured to

confirm the dimensions and the system

layout should be prepared. The location of

the electrical roof penetration and wire

run should be determined, if wiring is

planned for this area.

160

Start

Consumer can check with the agencies under MNRE in their sub-division and district directly stating the need for solar

photovoltaic system.Consumer can also directly contact CEL stating the need for

installing PV system and know if PV can be installed on consumer’s location

Planning Approval required?

Formal development application must be submitted to the nodal agency via CEL or other agency.

Allow 4 weeks time for evaluation and approval

Consumer can appoint the PV system contractor to take full responsibility of setting up the system

OrConsumer can use the “Reference Handbook” and install the

PV system with help of an qualified person.

Does Area available for panels

comply with load requirement?

Select shade free area during peak sunshine hours

Decide on the type of module mounting

Connectivity with grid?

Standalone PV system

Grid interactive PV system

How much load to be replaced by solar PV

system?

Use the STEP by STEP installation procedure given in

the handbook to set up the SPV system

Using Handbook get the required items and seek help of qualified person if required or

enquire at CEL

Consumer appoint agency or CEL to do the

full installation

END

FULL LOAD

PART OF TOTAL LOAD

NO

YES

END

YESAnalyze roof

structure and check structural strength.

NO

NO

YES

List out specific load and hours of operation

Flowchart :5.2 going ahead with installation of SPV system

161

SOLAR POWER SYSTEM INSTALLATION LOCATION

1. Solar modules should be

installed facing south, if possible.

Installations facing east and west are

also possible, although the amount of

power generated will be lower. The

roof should be checked from a

southern orientation, and checked for

obstacles that will cast a shadow.

Since these factors lower the amount

of power generated.

2. Installation should be done in a location that has good sun exposure

throughout the year. Less power is generated in shaded locations.

3. Installation is not

possible in regions where the

wind pressure exceeds 45 PSF. It

should be checked with the local

building department to

determine if this mounting

system is in compliance.

Installation is not possible when

the roof angle is less than 10

degrees or greater than 45

degrees.

4. The output of a series string of solar modules is connected to the input of

the inverter. Solar modules should always be installed so that all elements

of the array receive the same amount of sunlight. The amount of power

generated declines dramatically if the solar modules are connected

receiving different amounts of light in a string array, for example, solar

modules facing east and solar modules facing south should not be

connected in the same string.

5. It may not be possible to install solar modules in the following areas and

under the said conditions. Regions with heavy snowfall - Installation is not

possible in regions where snow accumulate

162

6. Ion exceeds the maximum allowable load. The building department should

be contacted for more information about maximum snow accumulation.

Configuration

A typical Solar Photo Voltaic Power Plant comprises PV Array, Solar deep cycle

battery and Power Conditioning Unit (PCU). PCU comprises a charge controller, an

inverter for conversion from DC into AC and a complete set of installation hardware.

Fig 5.2 A schematic diagram of the proposed system.

The modules have been fixed on corrosion resistant MS Structure. The SPV module

has crystalline silicon solar cells connected in series and hermetically sealed with

high transmission toughened glass on top and suitable lamination material on back

using state-of-the-art technology. The laminates are framed using anodised

aluminium Channels. A terminal block is fixed on the frames for taking the electrical

output. The SPV Array is grouted on Galvanized MS Support Structure. Each

Structure carries a certain number of modules. Each module contains a bypass diode

of suitable rating to prevent the partial shadow effect. The Modules on each

structure are electrically connected in ‘n’ Series and ‘m’ parallel combinations. The

outputs from individual ‘n’ Series are brought to Panel Junction Box (PJB) mounted

on structure. Outputs from the structures are connected in PJB for paralleling by

using fuses and blocking diode of suitable rating.

163

The outputs of ‘m’ no’s of PJBs are divided into sub arrays. The outputs from

individual PJB of a sub array are paralleled in respective Field Junction Box (FJB).

5.2.4 Mounting

Permanent solar panel installations require installing mounts for the solar

panels. These can be stand-alone mounts that allow you to mount the panel in

open space or roof mounts that allow the panels to be held stable on the roof of

your house. Each has specific advantages and disadvantages. If mounting on a

stand-alone frame, you will have easier access to the panels, allowing easier

maintenance and manual adjustment of the panels. Mounting the panels on the

roof keeps the system elevated and integrates the solar panels into the existing

installation, making them unobtrusive. In both cases, the consumer can buy

mounts from a green energy company, hire a contractor to install a system or

build the system on her own.

Instructions:

Table 5.1 Materials required:

1.Tape measure

2.Cement

3.Threaded rod and nut

4.Suitable solar system mounts for a particular roof system

5.Chalk line

6.Drill

Flowchart 5.3 Creating a Stand-Alone Mount

Measure the size of the solar array. Based on them, determine where you will pour concrete piers.

Dig holes at chosen locations and pour in concrete to create a concrete pier. Place bracket in

the concrete piers to connect the panels to the mount. Allow them to dry.

Attach the solar panels to the front concrete piers and the rear rods using bolts. This system allows the solar panel's angle to be adjusted by turning

the pipe.

Space the front piers to meet the bottom of the solar array and rear piers at the same width and at a front-to-back distance facilitating mounting

the panel at approx 30 degrees.

Location for the stand-alone mount. Area should be free of obstructions that block the sun. Should

facilitate mounting the panels facing south.

164

Flowchart 5.4 Roof Mounting

Using a stud finder, locate rafters under the roof surface. Set a solar rack mount above the stud and

drill a guide hole through the middle.

Attach metal channels to the mounts. Channels are long square sections of metal, similar to metal

pipes, that will serve as the base for the solar array.

Ensure a straight line across the roof by laying out a chalk line. Repeat, place mounts for the panels

above the rafters in a straight line across the roof.

Measure and mark the space that will be used to mount the array. If possible, place the array on a south-facing roof away from light obstructions.

Bolt the solar rack mount into the roof. If the mount comes with a post, screw the post into the

mount.

Attach the solar panels to this base.

Fig 5.3 Module Mounting

165

Once it is ascertained that the solar array is correctly assembled it is time to lift it

into place and secure it. Usually there are a number of rails to be mounted to the

roof or foundations first. It should be ensured that these are orientated correctly

so that the solar array will point towards the equator once mounted; that is

towards the south in the northern hemisphere and towards the north in the

southern hemisphere.

Often the best method is to place two ladders parallel to each other and walk up

them with the solar array in between.

The solar array should be carefully lifted into position on the mounting rails and

assembled using the correct nuts and bolts. If the mounting structure is

adjustable for tilt, now is the time to set it. The solar array should be supported

whilst making any adjustments and set the tilt based on the latitude of the

location as follows:

Optimized for winter, e.g. lighting systems in temperate zones: Angle of

latitude +15º from the horizontal.

Optimized for summer, e.g. holiday homes: Angle of latitude -15º from the

horizontal.

All year round performance, e.g. medical systems in the tropics: Angle from

the horizontal equal to angle of latitude.

The tilt should not be set less than 10º from the horizontal whatever the latitude,

as a tilt of less than this will allow dirt to build up on the solar array which will

reduce its performance.

5.2.1 Assembly

Before fixing to the roof or ground the solar panels must be mounted to the

support rails to create a single unit. In larger systems the solar array may be split

into sub-arrays. Each of these is treated as a separate solar array.

If a proprietary support structure is used then the correct nuts and bolts will be

supplied. Otherwise use high-tensile nuts and bolts the correct size for the

mounting holes in the solar panels, and ensure that either locking washers or

self-locking nuts are used to prevent loosening as a result of vibration due to the

wind.

The solar panels should be laid face down in the correct alignment. It should be

ensured that the ground is flat; a grassed area is ideal. A blanket should be

placed or similar on the ground to avoid any damage to the glass. The mounting

rails should be bolted to the solar panels, taking care to ensure that no strain is

166

placed upon the solar panels. Weight should not be put on the solar

panels themselves.

5.2.2 Connection

It is usually easiest to connect the individual solar panels together and connect

the long output cable to them before putting them into position, especially if

they are to be roof mounted. Connect all the solar panels together first; either in

one, two, or four groups depending on the system voltage and then connect the

output cable. Check that all connections are sound before replacing the terminal

box covers as this is hopefully the last time you will see them.

A solar module structure is of two types:

a) Stand-alone

b) Grid tied

The structure has 8 parts, two horizontal, two vertical and four legs.

There are two kinds of nuts used for the structure build up.

The nuts are of M6 and M16 type.

M6 is used for module mounting

M16 is used for mounting structures and is Stainless Steel hardware.

The vertical legs are classified as small and long. A difference is maintained in their

heights to get desired inclination of the mounting structure.

167

M16 type of Nut used for

mounting structure

Entire structure used for

mounting. These individual parts

are assembled with the help of

nuts.

Pliers and spanners are used for

fixing and tightening the nuts.

Spanners used for this purpose

are of 10-11 and 18-19

dimensions.

Fixing of nuts (M16) for fixing

the structure.

Tightening of nuts using spanner

(18-19 dimension).

M6 type of nut used for

mounting the module on the

structure.

Vertical legs of the mounting

structure.

168

The second vertical leg is fixed.

Placement of vertical and

horizontal sections for modules

to rest on.

The above structure is inverted.

All the bolts of the entire

assembly structure should be

properly tightened.

The vertical legs should now be

fixed and bolts should be

tightened.

This is how the structure should

look, with the long legs placed

on one side and the short ones on

the other side to provide an

inclination for the placement of

solar modules at a particular

angle for maximized output.

169

Grouting of the Galvanized MS

Structures.

The solar modules are now

mounted on the structure one by

one.

Pedestals are Reinforced Cement

Concrete structures and should

be built on the ground/roof

where the structure has to be

mounted. This is an important

step for providing a firm base to

the modules.

The module is placed on the

structure and fixed using M6

bolts.

Spanner (10-11) is used for

tightening the bolts.

170

Open the junction box of the

module and connect the module

cable with correct polarity.

Close the junction box and tie the

module cable on the module

frame.

Positive and negative wire

connections made behind a solar

panel.

To connect the modules in series, the positive of one module is connected to the negative of the adjacent module and so on.

171

The first and the last module are left with two free ends of +ve & -ve outputs which are then connected to the charge converter.

Wires are put in casing.

Wiring between sub-arrays

ARRAY JUNCTION BOX

(This is how the output cables of

arrays are junctioned). For

instance in this case the number

of panels is 7.

172

Main junction boxes for

paralleling of the junction boxes.

For installing the home controller, first open the product.

Fix the base plate to the wall. For

fixing the product in wall marks

& makes 4 hole of drill size

6.5mm

RFID is pasted behind every

solar module. This signifies the

characteristics of every panel like

the current, voltage etc.

Separate PCB fixed Base plate

and Top cover.

i

On the base plate, where the PCB is mounted, labels for connections are marked. Connections are to be done according to the labels. Before the terminal fixing, grommets are to be inserted to the cables.

Place the Top cover on the base plate and fix with screws and put the screw caps supplied along with.

5.3 Battery

Installation of the battery may be as simple as taking a wet-charged or sealed

battery out of a box and placing it on a firm and level surface.

Alternatively it may involve mixing

acid to the right concentration and

filling the batteries on site.

Fig : picture of EXIDE solar battery

5.3.1 Site

The batteries need to be mounted such that they are secure, i.e. they can’t fall

over, they are protected from unauthorized access and away from sources of

ignition. The room or container that they are in should be ventilated so as to

allow the hydrogen produced by charging to escape. This applies even to sealed

ii

batteries as they are able to vent excess gasses should the charging system

malfunction.

Practically this is most likely to mean one of two things:

On a solid floor or racking within a locked and well ventilated

room.

In a purpose designed battery box.

It is important that it is possible to gain access to the batteries in order to

perform maintenance. In the case of a sealed battery this means the terminals,

but for a vented battery it may mean access to the level markings on the side and

the filling caps.

Connection

Table 5.2 Materials required for connection:

1. Solar panel

2. Deep cycle lead/acid battery

3. Battery box

4. DC power meter

5. DC Power input

6. Red and black insulated power

7.Wire cutters

Fig 5.4 Schematics showing electrical connections

iii

Flowchart 5.5 for making electrical wiring connections

Connect the power meter to the battery using insulated wire.

Connect the positive battery terminal to the positive terminal on the meter using red wire.

Connect the negative terminals using black wire.Keep the color / terminal match the same throughout.

Connect the DC input to the battery using insulated wire.

Connect the solar panel to the battery using insulated wire.

Connect additional batteries to the first battery if more power is desired.

Put the panel in the sun so that it begins charging the battery. Once charged, the plug on the DC input can be

plugged into various appliances to run them off the battery charge.

Once the battery has been put in place, the individual batteries or cells can be

connected together to form a single battery. If possible battery interconnect cables

supplied by the battery manufacturer or supplier should be used; and if it has to be

made then the thickest cable that is practical should be used.

Great care should be taken when connecting the batteries.

All metal jewellery should be removed before starting.

Insulated tools should be used where available.

Output cables should not be connected at this point.

5.3.4 Earthing

Provision should be made to earth the battery negative terminal. If no suitable

earth is available, then an earth rod must be driven into the ground outside as

near as possible to the battery. This is connected to the battery negative terminal

via green and yellow earth cable of at least 2.5 mm2 and preferably 6 mm2 cross-

sectional areas.

iv

a. Control equipment

POWER CONDITIONING UNIT

The single phase Power conditioning unit

(PCU) provides single phase AC power to

the specific loads with an objective to

reduce the dependency on conventional

power as well as to minimize the

consumption of fossil fuel (e.g. Diesel) in

the event of power failures.

The power conditioning unit mainly comprises of MPPT based, PWM solar charge

controller, and a single phase bi-directional inverter.

The MPPT charger is microprocessor based system IS designed to provide the

necessary DC/AC conversion to maximize the power from the SPV array to charge

the battery bank. The charge controller is equipped with necessary software that

allows precise charging of the battery bank .Many protection features are also

included to ensure that no abnormal or out of range charge conditions are

encountered by the battery bank. The system incorporates a front panel display to

indicate the ‘operational status’ and ‘fault status’ of the system, reset system faults

and implement various operating modes.

The high efficiency inverter converts the DC power available from the Array/Battery

into single phase AC, by incorporating IGBT devices for power conversion. When

AC mains is available, the inverter control system uses the internal set point to

monitor the condition of the AC source to determine if the quality of AC mains is

suitable for being to the load. If the AC quality is found to be within specified limits,

it is connected to the load. In the event of power failure and the solar power is

available ,the control attempts to maintain zero current from the battery, thus

transferring as much as possible solar current to the load. During this time the

battery voltage is monitored continuously. When the solar energy is not available

(due to insufficient sunlight) the system enables the battery to deliver the current

through inverter to meet the demand. The microprocessor controlled inverter

incorporates Pulse Width Modulation (PWM) technology and incorporates all the

desired safety features (please refer data sheet).

Important features/protections in the PCU:

MPPT included.

LCD keypad operator interface menu driven.

Automatic fault conditions reset for all parameters like voltage, frequency

and/or black out.

v

MOV type surge arrestors on AC & DC terminals for over voltage protection

from lightening induced surges.

PCU operation from 5°C to 55 ° C

All parameters shall be accessible through an industry standard

communication link.

Over load capacity (for 30 sec) shall be 150% of continuous rating.

Since the PCU is to be used in solar photovoltaic energy system, it shall have high

operational efficiency. The idling current at no load shall not exceed two percent of

the full load current. In PCU, there shall be a direct current isolation provided at the

output by means of a suitable isolating transformer.

Internal faults: Inbuilt protection for internal faults including excess temperature,

commutation failure, and overload and cooling fan failure (if fitted) is obligatory.

Galvanic Isolation: Galvanic isolation is required to avoid any DC component being

injected into the grid and the potential for AC components appearing at the array.

Over voltage protection: Over voltage against atmospheric lightening discharge to

the PV array is provided.

A. Earth Fault Supervision: An integrated earth fault shall be provided to

detect eventual earth fault on DC side and shall send message to the

supervisory system.

B. Cabling Practice: Cable connections shall be made using PVC Cu cables,

as per BIS standards. All cable connections shall be made using suitable

terminations for effective contact.

All doors, covers, panels, and cable exits shall be gasketed or otherwise designed to

limit the entry of dust and moisture.

In the design and fabrication of the PCU the site temperature 5 °C to 50 °C, incident

sunlight and the effect of ambient temperature on component life have been

considered carefully. Similar consideration has been given to the heat sinking and

thermal for blocking diodes and similar components.

INVERTER CONNECTIONS:

Fig 5.5 : Inverter for 1MegaWatt

power station

The controller, inverter and any

other control and monitoring

equipment can now be installed.

vi

There are four components to be connected together:

solar panels,

charge controller,

batteries and

inverter

The charge controller is needed to make sure that the batteries are not

overloaded.

The inverter is needed to convert Direct Current (DC) to Alternating Current

(AC). Most home appliances run on AC and the output from solar panels and

batteries are DC.

Connect the solar panels together so that the voltage output will match the batteries

Connect the positive and negative outputs of the solar panel array to the positive and negative inputs to the charge

converter. The positive and negative outputs or the charge controller are connected to the positive and negative terminals

of the battery bank.

Connect the positive and negative terminals of the battery bank to the positive and negative inputs of the inverter. The outputs of the inverter are connected directly to the house

wiring

i. Connecting two panels (or similar groups of panels) in series will double the

voltage, but keeps the current the same. Wiring two panels (or similar groups

of panels) in parallel keeps the voltage the same but doubles the current.

Figure out the voltages for the panels and batteries so that they match before

buying anything. Also make sure that the ratings for the charge controller and

the inverter match the voltages for the panel array and the battery bank

before buying anything.

ii. Connecting two batteries (or similar banks of batteries) in series (the positive

terminal of one to the negative terminal of the other) will double the voltage

while keeping the current the same. Connecting two batteries (or similar

banks of batteries) in parallel (both positive terminals connected together and

both negative terminals connected together) will keep the voltage the same

while doubling the current.

iii. It is important that the voltage ratings to all four major components (solar

panels, current controller, batteries and inverter) match. The panels and

batteries can be wired in combinations that bring the total networks up to the

required voltages--the networks need not be mirror images of each other as

long as the totals match.

vii

5.4.2 Wiring

The wiring may now be put in place, following the diagram and cable sizes.

Great care should be taken to observe the correct polarity, and ensure that all

connections are well tightened. The cables should be securely clipped to the wall

where it is possible to keep them out of harm and make them look neat. Any of

the final positive connections to battery, solar array or load should not be made

at this stage.

All wiring must be installed in conformity with local electrical regulations, by a

qualified electrician where necessary.

5.5 System Commissioning

System commissioning is the process of checking and testing the installation and

putting it into service. It may be tempting to hurry this procedure; time may be

running short and the user may be impatient to see the system working.

However, the future reliability of the entire system depends on careful

commissioning. If the equipment you are using has any specific commissioning

instructions then follow those in preference to the instructions below.

5.5.1 Visual check

With the help of the wiring diagram the system should be carefully examined to

ensure that everything is as it should be. Particular attention should be paid to

the polarity of connections and the battery earth.

5.5.2 Connections

The security of all the connections to the control gear and any other connections

that have been made already, such as the battery negative and earth connections

should be checked.

5.2.3 Testing output of solar panel

To Test the Power Output of a Solar Panel with a Multimeter, the instructions are

given below:

Instructions

Table 5.3 Materials required for testing:

1. Solar panel

2. Multimeter

viii

Flowchart 5.6 testing process flow

* It is wise to turn the

panel away from the sun to

measure the current as the

panel is live when the sun is

shining on its face.

Connecting to the live

junctions when testing the

current can cause sparking.

** It's not unheard of to

get a slightly higher reading

than the current rating

listed on the panel, so you

want to see at least a

matching number. If both

the voltage and amperage

test properly, then it’s a

good panel and will serve

well.

5.5.3 Applying power

With any load isolators or circuit breakers switched off, the loads to the

controller and / or inverter should be connected.

Next, the battery terminal voltage should be recorded and measured and

the battery positive terminal should be connected. The battery fuse

should be inserted, if fitted. Since a spark is likely to occur, ensure that the

room is well ventilated and the battery caps should be blown across first

to clear any hydrogen if the battery is of the vented type.

• Beware of newer glass panels that have cracks or condensation under the glass. The conductivity is likely compromised, meaning you can probably leave your multimeter in your pocket.

Tips & Warnings

ix

The voltage at the battery connections of the controller and inverter

should be measured. This should be the same as the battery terminal

voltage. If not, all the connections and the battery fuse should be checked.

Finally, the photovoltaic array should be connected. Before doing this,

cover it with an opaque material if possible; and it should be removed as

soon as the connection is secure. The voltage at the input terminals of the

controller should be measured – this should be the same as or slightly

higher than the battery terminal voltage.

If there is a reasonable amount of daylight then the controller should

show that the battery is charging. It should be checked that the battery is

actually charging by measuring the terminal voltage, which should be

higher than that initially recorded and rising.

Now the loads should be switched on. All the loads should be checked, if

there is more than one, to make sure that they work.

The commissioning process is now complete.

x

RECOMMISSIONING

Repeating the commissioning of a system that was previously commissioned is

called re-commissioning. Usually, re-commissioning should be the last step in any

substantial maintenance project, such as after replacing major components, especially

inverters; after adding additional modules; after a non–self-clearing alarm is

diagnosed and repaired, such as a ground fault; and as part of a system checkup or

regular annual maintenance visit. In addition, if the original commissioning was

performed during less than optimal seasonal conditions, like shading or extended

poor weather, a re-commissioning event may be called for during better conditions

or in the summer. Re-commissioning results should be closely compared to those

from the original commissioning. if the results are inconsistent (after accounting for

shading or other changes), the system integrator should track down the source of the

inconsistencies. Re-commissioning performance results should also be compared to

updated expected performance numbers and discrepancies addressed.

PARTS AND TOOLS

STANDARD PARTS

DOCK WASHER (Anti corrosion coated steel)

BOLT (Stainless Steel)

MODULE MOUNTING CLIP (Anti corrosion coated steel)

THREADED TAB (Anti corrosion coated steel)

SPLICE

(Anti corrosion coated steel) SLIDE COVER (Aluminium)

SLIDECOVER SCREW

ROOF TILE PARTS

TILE ROOF BOTTOM BUTYL PAD (Anti corrosion coated steel)

TILE ROOF TOP BUTYL PAD (Anti corrosion coated steel)

SUPPORT PLATE (Aluminium)

SUPPORT SCREW (Stainless)

STANDARD SLIDER MOUNTING SCREW (Stainless)

TILE ROOF STAND OFF SCREW (Stainless)

xi

MEASUREMENT

SCALE COMPASS SOLAR INSOLATION METER

DIGITAL MULTIMETER

TOOL KIT

CORDLESS DRILL SOCKET DRIVERS

DRILL SCREW DRIVER SET NEEDLE NOSE

PLIERS

LINE MAN’S PLIERS WIRE CUTTERS HAMMER CHISEL CRIMPING

TOOL

KNIFE TAPE MEASURE EXTENSION CORD CHALK LINE GLOVES &

SAFETY HELMET

TOOL BELT ROPE LADDERS SAFETY

HARNESS AIR MASK

SAFETY GLASSES CALCULATOR GROUND

WIRE ELECTRICAL TAPE PENCIL

xii

6 APPLICATION AREAS

6.1 HABITAT APPLICATIONS

6.1.1 Solar Lanterns

CEL SOLAR LANTERN is a versatile and

reliable source of lighting. It comprises a

Lantern, Solar Photovoltaic (SPV) module and

a connecting cable. The SPV module when

exposed to sunlight charges the battery in the

lantern. This stored energy in the battery is

used to operate the lamp when required.

Solar Lantern consists of a 7W CFL (light out

put equivalent to a 40W incandescent lamp) which can be used for 3-4 hours daily.

The system comprises SPV Panel, lantern (with maintenance free lead acid battery)

and a detachable connecting cord.

Soar PV Module

A number of high grade crystalline Silicon Solar Cells, interconnected in a series

combination and hermetically sealed with a toughened and highly transparent front

glass cover, from the SPV Module. CEL's Solar Lantern is the final and latest answer

to many lighting problems.

Salient Features

1. Environment Friendly 2. Rugged and Dependable

3. Portable 4. Light output 400 lumens i.e. equivalent

to a 40 watts incandescent lamp

5. Silent Operation 6. LED for battery status indication and its

safeguard Applications

1. Emergency Light Source 2. Garden Lighting

3. Picnic Sports and Farm Houses 4. Military Outposts

5. Light sources for the field personnel of Agriculture extension, Adult Education and other Mass Communication Programmers

6. Light Source in remote un-electrified villages

Specifications:

Components Ratings

1. Solar PV Module Wattage 10 -12Wp

2. Operation per Day 3-4 Hrs.

3. Light bulb 7 Watt Compact Fluorescent Lamp

4. Battery 12 Volt/7AH Sealed maintenance free.

xiii

6.1.2 Domestic habitat light & fan system

CEL's Domestic Lighting Systems provides un-

interrupted light and is completely noiseless,

smoke-free, and free from fire hazards. The

independent lighting system consisting of

Compact Fluorescent Lamps (CFL) fixtures, a

storage battery powered by the SPV Module

provides 3 to 4 hours of light per day.

Applications

1. Houses 2. Clinics

3. Schools 4. Holiday Resorts

5. Offices 6. Huts and Cottages

7. Bank 8. Other Indoor Applications

CEL's Solar Domestic Lighting Systems are easy to install and requires minimal

maintenance. CEL can supply Customized System also.

Specifications

SPV Home Lighting System

SPV Module Battery CFL -9

W Charge

Controller

M.S. Structure & wiring Set

MODEL I PM 20 - 1 No 12V, 20AH 1 Nos 3 Amp 1 Set

MODEL II PM 37 - 1 No 12V, 40AH 2 Nos 5 Amp 1 Set

MODEL III PM 75 - 1 No 12V, 80AH 4 Nos 6 Amp 1 Set

6.1.3 Outdoor & street lighting system

CEL's Solar Street Lighting System provides

Bright Light during night. The system

completely Noiseless, Smoke-free and Free

from Fire Hazards. This is a stand-alone

lighting system consisting of Lamp Assembly

(with control electronics) with one Compact

Florescent Lamp (CFL) of 11 Watt, a Storage

Battery charged by the SPV Modules and

provides lighting during night hours. It works

automatically from Dusk to Dawn.

xiv

Applications

1. Path Lighting 2. Township

3. Farm House Lighting 4. Holiday Resorts

5. Campus Lighting 6. Watch Tower Lighting

7. Warning Signals at Railway crossings

8. Railway and Shipyard Lighting

Specifications

Each SPV Street Lighting System comprises of following

1. SPV Module Type PM-75 1 No.

2. Battery 12V,80AH 1 No.

3. Pole Assembly 1 No.

4. Battery Box 1 No.

5. Lamp Assembly 1 No.

6. Wiring Set 1 Set.

CEL's Solar Street Lighting Systems are easy to install and requires minimal

maintenance. CEL can supply Solar Street Lighting System with SPX Lamp or as per

choice of customer.

6.1.4 Water pumping system

CEL's Solar Photovoltaic Water pumping system

is modular, flexible and is available in two types

i.e. Shallow well type and Deep well type. They

are ideally suitable for those areas where

conventional grid supply is either erratic or non-

existent. CEL's Solar Water Pumping System

requires minimal maintenance. These systems

don't require batteries. DC power generated by

Solar Modules is directly fed to the pump.

Applications

Drinking water Agriculture related use

Irrigation Horticulture

Animal Husbandry Poultry farming

Aquaculture High value crops

Orchard Farming

xv

Shallow Well Water Pumping System (Model SW 1800)

Components Ratings

1. SPV Panel 1800 Wp

2. Type of Pump Centrifugal DC Monoblock

3. Max. Suction Head 6.0 meters

4. Max. Total Dynamic head 12.0 meters

5. Capacity of Motor 2 HP

6. Mounting structure MS hot dipped galvanized with three times Manual tracking facility

Water Output

The system would deliver 1,30,000 liters per day at 10m total dynamic head on a

clear sunny day with three times tracking of SPV panel when solar radiation on

horizontal surface is : 5.5 KWH/sq.m/ day.

SPV Deepwell Water Pumping System (Model DW 1200)

Components Ratings

1. SPV Array Wp 1200

2. Type of Motor Pump set Submersible

3. Max. Total Dynamic head

70.0 meters

4. Mounting structure MS hot dipped galvanized with three times manual tracking facility

Water Output:

The system would deliver 30,000 liters per day at 30m total head and 12,000 liters per

day at 70m total head on a clear sunny day with three times tracking of SPV panel

when solar radiation on horizontal surface is: 5.5 KWH/sq.m/ day.

SPV Deep well Water Pumping System (Model DW 1800)

Components Ratings

1. SPV Array Wp 1800

2. Type of Motor Pump set Submersible

3. Max. Total Dynamic head 70.0 meters

4. Mounting structure MS hot dipped galvanized with three times manual tracking facility

Water Output:

The system would deliver 42,000 liters per day at 30m total head and 19,000 liters per

day at 70m total head on a clear sunny day with three times tracking of SPV panel

when solar radiation on horizontal surface is: 5.5 KWH/sq.m/ day.

xvi

6.2 INDUSTRIAL APPLICATIONS

6.2.1 ONGC offshore power

Offshore platforms that pump oil and gas under the sea are unmanned and need to

be remotely monitored. It becomes vital then, for the power system to be highly

reliable, long lasting, well-engineered and capable of operating in a vast spread of

conditions. The ONGC module is a pioneering intrinsically safe double glass module

developed specifically for operation in explosion prone environments, such as on the

offshore, oil production platforms of ONGC.

These are the 1st modules in the world to be certified with Gr.I, Gr.IIA and Gr.IIB by

Central Mining Research Station (CMRS), Dhanbad and accepter by international

insurers, Lloyds of U.K.

The solar power generation system used on the ONGC wellhead offshore platforms

powers telemetry, gas detection, lighting and navigational aid systems.

The system comprises of

1. solar modules for hazardous area application 2. battery bank

3. an explosion proof junction box 4. nav-aid lantern

5. marine-grade structures with special coating for PV modules

6. fire-survival cables

6.2.2 Very Low Power TV Transmitter & Radio Receiver

xvii

6.2.3 Obstruction Warning Lights at Airports

The obstruction light is a system of red lights

used to show the presence of manmade or

natural objects that are dangerous to airway

path.

These obstruction lights are now days made

from LED, Xenon Lamps, Neon Lamps,

Incandescent lamps etc.

Obstruction lights shall be located as close as practicable to the top of the object.

Obstruction lights are installed on all obstructions that present a threat to air traffic,

cautioning pilots of the presence of an obstruction during hours of darkness and

during periods of limited daytime visibility. The use of solar energy to illuminate the

Obstruction Lights during day time will be more economical and viable also

environment friendly and save electricity.

6.2.4 Railway signalling (Supplementary Power)

The efficient running and control of railway

traffic, one of the largest means of transportation

in the country is seriously hampered by

irregular grid supply, often resulting in traffic

congestion and great inconvenience to public

and adversely affecting the operating cost.

The alternative method of supplementing grid

supply by the use of Diesel Generator sets pose

considerable logistic problems. It has a high maintenance cost, necessitating use of

additional DG Sets as stand-by. Diesel oil has to be transported to the far-flung

location at prohibitive cost. Diesel oil is further prone to pilferage. Thus this

alternative becomes extremely costly, apart from disadvantage of atmospheric

pollution.

As a result of decade of research and field experience CEL now brings the source of

power – Solar PV power source by harnessing the Solar Energy abundantly

available and non-polluting by nature. CEL SPV power system comprising of the

Solar Photovoltaic arrays, storage batteries and control electronics now offers the

best alternative power source for panel station of Indian Railways.

A typical SPV power source for Panel Stations for Railways consists of:

A Solar Photovoltaic Array.

A Battery Bank.

An Electronic Control Unit and Panel.

xviii

6.2.5 Telecom towers

As many as 400 telecom towers are to be powered by solar panels that will sit on

them, reflecting light from the sun to produce electricity that will be used by the

towers. The towers are part of a Rs 120 crore project under the Jawaharlal Nehru

National Solar Mission (JNNSM) of the Ministry of New and Renewable Energy.

The 400 projects include 100 each for telecom operators Bharat Sanchar Nigam Ltd.

(BSNL, New Delhi, India), BhartiAirtel Ltd. (New Delhi, India), Indus and GTL Ltd.

(Navi Mumbai, India).

The towers are located in multiple Indian states, with GTL's 100 tower PV projects in

Uttar Pradesh, Indus' 100 systems in Andra Pradesh, and Airtel's 100 systems in

Bihar.

Multiple economic analyses have indicated that PV systems are far more cost-

effective over time for supporting telecom applications in off-grid areas than diesel

generation, even before the inherent uncertainty in fuel costs is factored in. Thus

CEL being one of the largest manufacturers of solar cells in India, telecom towers

will be considered as one of the markets for using solar PV as an industrial

application.

xix

6.3 DEFENCE USE

6.3.1 Lightweight foldable solar charger for Manpack Radio Equipment

CEL's Lightweight,

Foldable Solar Charger is

suitable for charging 12 V,

18 V and 24 V Lead Acid

and Nickel Cadmium

batteries for Manpack

Radio Equipment. This

solar charger is specially

designed to meet Joint

Service Specifications

55555 and is ideal for

charging batteries at

difficult and inaccessible

areas a temperature

varying between -30°C to

+65°C.

The Lightweight Solar Charger has been designed for use by the Army and Para-

military Forces for charging re-chargeable lead-acid and nickel-cadmium batteries

used in low power manpack radio sets, The Solar Charger totally eliminates the

second set of batteries and/or heavy manually operated generating set (with fuel)

that normally form part of a manpack radio detachment thereby reducing at least

one man-load. It is hence most suitable for the soldiers operating at high altitudes,

remote and inaccessible areas and for long range patrols.

The Solar Charger consists of a pair of foldable solar photovoltaic (SPV) panels. Each

panel is of 24 W capacity and capable of charging a 12 V battery. The two panels can

be connected in series or parallel for charging 24V/18V or 12V battery systems as

required.

The charger is provided with a support stand for the SPV panel, an Indication Unit

having a current meter and requisite connectors; all capable of being assembled and

packed in a water-proof carrying harness. Indication Unit helps the user to correctly

orient the SPV panel for capture of maximum sun insolation and also know the

charging current.

xx

Features

Lightweight

Foldable & easy to carry

Ideal for remote locations

Easy to assemble & operate

No moving parts & no noise

Maintenance free

Technical specifications

Parameter Single

Panel

Two Panels in

Parallel

Two Panels in

Series Open circuit voltage (Voc)

Volts

20.50 20.50 41.00

Short circuit current ' (Isc)

Amp.

1.75 3.50 1.75

Peak electrical power (Pm)

Watt

24.00 48.00 48.00

Peak charging current (Im)

Amp.

1.50 3.00 1.50

Suitable for battery 12V 3 to

7AH

12V 5 to 12AH 24V/18V 6 to 7

AH These electrical parameters are measured at standard test conditions (STC) of 100 mW/Sq.cm cell temperature of 25°C and Air Mass of 1.5. Weight of Solar charger with all accessories

Single panel — 4.0 kg.

Two panels — 7.5 kg.

Environmental

Specifications subject to change without prior notice due to continuous in-house

improvement. Measurement accuracy within +5%

Operating Temperature range -30°C to +65°C

Storage Temperature Range -40°C to +70°C

Relative Humidity 95% max. at 40°C

xxi

6.3.2 Lightweight foldable solar charger for Manpack Wireless Communication

Equipment SCU-01

CEL's Lightweight Foldable Solar

Charger is suitable for charging 12V

Lead Acid and Nickel Cadmium

batteries for Manpack Wireless

Communication Equipment. This

Solar Charger is specially designed to

meet Joint Service Specifications

55555 as per Table L.3 and is ideal for

charging batteries at difficult and

inaccessible areas to temperature

varying between— 30°Cto + 65°C.

Features

1. Lightweight 2. Foldable and easy to carry

3. Ideal for remote locations 4. Easy to assemble and operate

5. No moving parts and no noise 6. Maintenance free

The Lightweight Solar Charger has been designed for use by the Army and

Para-military Forces for charging rechargeable lead-acid and Nickel-

Cadmium batteries used in low power manpack communication sets.

The Solar Charger totally eliminates the carriage of back-up batteries and/or

heavy manually operated generating set (with fuel) that normally form part

of a manpack radio detachment thereby reducing at least one man-load. It is

hence most suitable for soldiers operating in high altitudes, remote and

inaccessible areas and for long range patrols.

The Solar Charger consists of a pair of modules (each module having 16

single crystalline solar cells, connected in series) with integral indication unit

and a support stake. The modules are again connected in series to charge a 12

V battery.Indication Unit helps the user to correctly orient the SPV panel for

capture of maximum sun insolation and also to know the charging current. It

consists of a current meter and pair of terminals for connecting the battery to

be charged.

A Schottky diode has been provided as blocking diode (to avoid reverse flow of current).

Support Stake has been provided on the back side of the charger to keep the charger at an angle for getting maximum sun insolation.

xxii

Electrical parameters

Parameter Values (Nom)

These electrical parameters are

measured at standard test conditions (STC) of 100 mW/Sq.cm., cell temperature of

25°C and Air Mass of 1.5.

Open circuit voltage (Voc) Volts 18.0

Short circuit current (Isc) Amps 1.3

Peak electrical power (Pm) Watt 14.0

Peak charging current (Im) Amps 1.0

Suitable for battery 12 V 1-4 AH

Mechanical

Solar Panel (Foldable)

Closed (mm)

Open (mm)

*with meter

assembly unfolded

Length 305 305

Width 266 *630

Height 45 22.5

Weight

Weight of Solar Charger - 2.2 Kg (Max.)

Environmental

Operating Temperature Range 30°C to + 65°C

Storage Temperature Range 40°C to + 70°C

Relative Humidity 95% max. at 40°C

Measurement accuracy Within ± 5%

Specifications subject to change without prior notice due to continuous in-house

improvement.

The Solar Charger is cleared by Inspection authority (Ministry of Defence, Govt, of

India) for induction in service for radio sets RS-HX (MAT-20M).

xxiii

7 MAINTENANCE & TROUBLESHOOTING

Recommended preventive maintenance work

It is a recommended that preventive inspection and maintenance works are carried out every six to twelve months. The PV modules require routine visual inspection for sign of damage, dirt build up or shade encroachment . soar PV system fixtures must be checked for corrosion. This is to ensure that the solar PV system is safely secured.

While the inverters functionality can be remotely verified, only onite inspection can verify the state of lighting surge arrestors, cable connections and circuit breakers. The following table shows some recommendations on the preventive maintenance, works on the component and equipment and the corresponding remedial actions to be carried out by the qualified personal.

S.No. Component / Equipment

Description Remedy / Action

1.

PV modules Check for dust/ debris on

the surface of PV module

Wipe clean. Do not use solvents other than water.

Check for physical damage to any PV module.

Recommend replacement if found damaged.

Check for loose cables termination between PV modules, PV array etc.

Retighten connection.

Check for cable condition.

Replace cable if necessary.

S.No. Component / Equipment

Description Remedy / Action

2. PV inverter Check functionality. Example: Automatic disconnection upon loose of grid power supply.

Recommend replacement if functionality fails.

Check ventilation condition.

Clear dust and dirt in ventilation system.

Check for loose cable terminations.

Tighten connection.

Check for abnormal operating temperature.

Recommended replacement.

xxiv

S.No. Component / Equipment

Description Remedy / Action

3. Cabling Check for cable conditions i.e. wear and tear

Replace cable if necessary.

Check cable terminals for burnt marks, hotspots or loose connections.

Tighten connections or recommend replacement.

S.No. Component / Equipment

Description Remedy / Action

4. Junction boxes Check cable terminals i.e. wear and tear or loose connections.

Tighten or recommend replacements.

Check for warning notices.

Replace waring notice if necessary.

Check for physical damage.

Recommend replacement/Troubleshoot

S.No. Component / Equipment

Description Remedy / Action

5. Means of isolation Check functionality replacement.

Recommend/Troubleshoot

S.No. Component / Equipment

Description Remedy / Action

6. Earthing of solar PV system.

Check earthing cable connection.

Recommend replacement/Troubleshoot

Check the physical earthing connection.

Retighten connection.

Check continuity of the cable to electrical earth.

Troubleshoot or recommend replacement

S.No. Component / Equipment

Description Remedy / Action

7.

Bonding of the exposed metallic structure of the solar PV system to lightening earth.

Check bonding cable conditions.

Recommend replacement/Troubleshoot

Check physical bonding connection.

Tighten connection and troubleshoot.

Check continuity of the bonding to lightening earth.

Troubleshoot or Recommend replacement

xxv

TROUBLESHOOTING

7.1 Light units not glowing and no low battery indication on charge controller.

Possible Failure

Possible Cause Action

Load cables

1. Breakage

Replace cable 2. corrosion

3. Loose connection

4. Improper connection

Verify the wire connections are tight, corrosion free and of correct polarity

Load centre 1. corrosion

Replace load centre 2. Mechanical damage

Light unit

1. CFL Replace CFL

2. Fuse Replace fuse of the same type

3. Electrical failure

Replace light unit 4. Dry soldering

5. Loose connection

Earth tag

1. Loose connection

Connect the wire to the metal strip and ensure proper connection

2. Improper fixing

Place the metal strip between the limbs of the CFL

Connector Assembly

1. Loose connection Replace connector

2. Pin Loose

3. Improper Fixing

Fix connector properly

Charge controller

1. Electronic Failure

Replace charge controller

xxvi

7.2 No charging indication on the charge controller

Possible Failure

Possible Cause Action

Solar module

1. Shading Remove the shades or change the location of the module and ensure maximum sunlight falls on the module

2. Dirt accumulation

Clear the particles on the module

Module cable

1. Breakage

Replace cable 2. Corrosion

3. Loose connection

4. Dry solder

Module 1. Broken

module Replace module

Charge controller

1. Electronic failure

Replace charge controller

7.3 Low duration

Possible Failure

Possible Cause Action

Installation 1. Shading

Remove the shades or change the location of the module and ensure maximum sunlight fall on the module.

2. Dirt Accumulation

Clear the particles from the module

Module cable

1. Breakage

Replace cable 2. Corrosion

3. Loose Connection

4. Dry Solder

Charge controller

1. Electric Failure Replace charge controller

2. Corrosion

Customer

1. Insufficient Charging

Charge the battery till full charge condition and check the duration

2. Improper Installation

Place the module in such ways that direct sunlight falls on panel for longer duration and during peak hours of the day.

Battery

1. Low capacity

Replace battery 2. Acid Leakage

3. Terminal Broken

xxvii

7.4 Incident switch off

Possible Failure

Possible Cause Action

Switch 1. Corrosion

Replace Switch 2. Mechanical Damage

Fuse holder 1. Corrosion

Replace Fuse holder 2. Mechanical Damage

Battery

1. Low Capacity

Replace battery 2. Acid Leakage

3. Terminal Corrosion

Charge Controller

1. Electronic Failure Replace Charge Controller

2. Corrosion

Load center

1. Loose Connection

Replace Load Center 2. Improper Fixing

3. Pin Loose

7.5 Breakage

Possible Failure

Possible Cause Action

Light diffuser (CFL)

1. Material Degradation Replace the item

2. Transportation

3. Customer Abuse

Warranty not applicable

xxviii

7.6 Lamp Flickering

Possible Failure

Possible Cause Action

CFL

1. Crimping not proper

Replace CFL 2. Improper fixing

3. Base Loose

4. Lamp blackened

Light Unit

1. Terminal corrosion

Replace Light Unit 2. Pin loose

3. Dry Solder

4. Loose Connection

Earth Tag 1. Loose connection

Connect the wire to the metal strip

and ensure proper connection.

2. Improper Fixing Place the metal strip between the limbs of the CFL

Load centre

1. Loose connection Replace load centre

2. Pin Loose

3. Improper Fixing Fix the load centre properly and ensure they are tight

Charge Controller

1. Electronic Failure Replace charge controller

2. Corrosion

7.7 Lamp Semi Glow

Possible Failure

Possible Cause Action

CFL

1. Crimping not proper

Replace CFL 2. Improper Fixing

3. Base Loose

4. Lamp Blackened

Light Unit

1. Corrosion

Replace Light Unit

2. Breakage

3. Pin Loose

4. Dry Solder

5. Loose Connection

Earth Tag 1. Loose Connection

Connect the wire to the metal strip and ensure proper connection

2. Improper Fixing Place metal strip between the limbs of the CFL

xxix

7.8 Lamp Blackening

Possible Failure

Possible Cause Action

CFL

1. Crimping not proper

Replace CFL 2. Improper Fixing

3. Base Loose

4. Blackening Premature

7.9 No Indication

Possible Failure

Possible Cause Action

Charge Controller

1. Electronic Failure Replace Charge Controller

2. Corrosion

Module Cable

1. Loose Connection Replace Module Cable

2. Improper Fixing Fix the cable properly and ensure that the connections are tight with correct polarity

SPV Module 1. Breakdown Replace module

7.10 Water entry or Insect entry

Possible Failure

Possible Cause Action

Light units

1. Installation of the system

Fix the light units in such a way that water should not enter the light units during rainy season.

2. Light Diffuser Check if the light Diffuser is broken or may be improper fixing of light diffuser.

Charge controller

1. Installation of the system

The charge controller which is fixed on the battery box should be located in such a way that water should not enter during rainy season.