sunpath explanation

8/9/2019 Sunpath explanation

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Copyright 2011 Surmount Energy Solutions Pvt. Ltd


Appendix 22


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Table of Contents

22.0 SOLAR PV ANALYSIS .................................................................................................................................... 4

22.1 EXECUTIVE SUMMARY ................................................................................................................................ 4

22.1.1 Project Features ................................................................................................................................. 4

PROPOSED SITE DETAILS .................................................................................................................................. 5

Solar Radiation Resource Assessment ............................................................................................................. 6

Solar Radiation over Mumbai .......................................................................................................................... 6

Sun path and Shadow analysis ........................................................................................................................ 8

Temperature .................................................................................................................................................... 8

22.1.2 Proposed Technology ........................................................................................................................ 9

Overview Solar Cell technology ....................................................................................................................... 9

Dirt and dust .................................................................................................................................................. 10

Interconnection of Photovoltaic modules...................................................................................................... 10

Overview Inverter technology........................................................................................................................ 11

System specifications ..................................................................................................................................... 11

22.1.3 Maintenance and Operation ........................................................................................................... 13

Estimation of power Output .................................................................................................................................. 13


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Lists of Figures

Figure 22.1.1-Proposed Location of Solar PV Plant................................................................................................. 5

Figure 22.1.2- ( Source: SWERA).............................................................................................................................. 6

Figure 22.1.3-Solar PV System................................................................................................................................. 8

Figure 22.1.4--Flow Chart ........................................................................................................................................ 9

Figure 22.1.5-Typical relationship between module current and module voltage............................................... 10

Figure 22.1.6- Graph of Voltage Vs Current .......................................................................................................... 11


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Lists of Tables

Table 22.1.1-System Specifications......................................................................................................................... 4

Table 22.1.2 - Solar Radiation.................................................................................................................................. 7

Table 22.1.3-Temperature(Source Meteonorm and PVsyst).................................................................................. 8

Table 22.1.4-Wind (Source Meteonorm and PVsyst).............................................................................................. 9


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22.0 SOLAR PV ANALYSIS

22.1 EXECUTIVE SUMMARY

The solar PV energy power project C66 is located in Mumbai. The project is aimed to produce electricity from

photovoltaic panels and is defined to have 25KW installed capacity.

The project site is located at Mumbai 192N Latitude and 731E Longitude. The weather data for Mumbai was

interpolated from nearest weather stations of Santacruz Mumbai. The analysis for solar radiations of the

project area was performed on Meteonorm 6.1.

The details feasibility study was carried out to generate renewable energy through Solar Photovoltaic

technology. The analysis was done to verify if building could achieve 1% energy to generate from renewable

source as required by LEED CS.

As per energy modeling analysis total building energy consumption comes around 15383007 Kwh/year.

Therefore to meet LEED criteria building should generate atleast 153830 Kwh/ year. As per renewable analysis

only 34900 Kwh/year could be generated. Therefore it is not considered to be feasible to installed Solar PV

system for this building.

22.1.1 Project Features

Sr No. System Specifications One (1) 25KW system

1 Project location C 66

2 Project Consultant Surmount energy solutions Pvt Ltd.

3 Plant capacity 25KWp

4 Type of technology Poly crystalline silicon

5 Type of system On grid

6 Panel wattage 175Wp

7 Total nos. of PV module 144

8 System Configuration 12 modules of 24VDC in series and 12 in parallel

9 System voltage 370VDC

10 Area required 400 sqm

11 Tracking mode Fixed at 20 from Horizontal

12 Grid interactive inverter

capacity4KW

13 No. of Inverters 6

14 PV Module Efficiency 13%

15 Performance ratio 71%

16 Annual energy generation 34.9 MWH/year

17 Estimated project cost Rs.45,00,000

18 Tools used Ecotect, Meteonorm, PVsyst.

Table 22.1.1-System Specifications


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PROPOSED SITE DETAILS

Site Details

The proposed location of the solar PV power plant, is C66 in BKC, Mumbai (192N Latitude and 711ELongitude). The proposed Solar PV panel layout mounted on open terrace with shadow free area is

shown in Figure 22.2.1

Figure 22.1.1-Proposed Location of Solar PV Plant


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Solar Radiation Resource Assessment

India is located in the sunny belt of the earth, thereby receiving abundant radiant energy from the sun. India

being a tropical country is blessed with good sunshine over most parts, and the number of clear sunny days in

a year also being quite high. The country receives solar energy equivalent to more than 5,000 trillion kWh per

year. India get 2300 to 3200 hours of sunshine per year and the annual global radiation is 4 5 Kwh/sqm/day,fairly spread over 80% of the country. The Global irradiance map on horizontal plane is India is shown in figure

below.

Figure 22.1.2- ( Source: SWERA)

Solar Radiation over Mumbai

The yearly global solar radiation in Mumbai (on horizontal plane) is 1847 KWH/sq m, the average maximum

solar radiation being 202 kWh/sq m in May and the average minimum being 120 kWh/sq m in July. The

weather file for the locations of Mumbai has been selected from METEONORM database. A program has been

developed to estimate the direct solar radiation over stationary surfaces using computer software PVsyst.Toolperforms the database meteo and components management. It provides also a wide choice of general solar

tools (solar geometry, meteo on tilted planes, etc), as well as a powerful mean of importing real data

measured on existing PV systems for close comparisons with simulated values.

PVsyst is well suited to detailed analyses of any system whose behavior is dependent on the passage of time.
http://www.pvsyst.com/5.0/tools.phphttp://www.pvsyst.com/5.0/tools.php


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Month

Glob Hor

kWH/sqm

Diff Hor

kWH/sqm

Beam Hor

kWh/sqm

Jan 143 56 87

Feb 152 56 96

Mar 192 69 123

Apr 198 73 125May 202 80 122

June 147 81 66

July 120 77 43

Aug 122 76 46

Sept 142 74 68

Oct 158 67 91

Nov 139 57 82

Dec 132 54 78

Yearly 1847 820 1027

Table 22.1.2 - Solar Radiation

Legend:Glob Hor: Irradiation of global radiation horizontal

Diff Hor: Irradiation of diffuse radiation horizontal

Beam Hor: Irradiation of beam


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Sun path and Shadow analysis

A site assessment involves determining whether the location of the PV array will be shaded, especially

between the hours of 9 a.m. and 4 p.m. solar time. This is important, as the output of PV modules may be

significantly impaired by even a small amount of shading on the array. Crystalline silicon module outputsare generally more susceptible to shading than thin-film module outputs, because the thin-film cell

structure traverses the full length of the module requiring more shading for the same effect. Inter-row

shading is when one row of modules shades an adjacent row of modules. A six-inch shadow from an

adjacent module is capable of shutting down a whole section of modules and can even shut down the

entire PV system down.

Figure 22.1.3-Solar PV System

The Sun path and shadow analysis with solar panels tilted at 20 from horizontal during winter solstice (Dec

21) has been performed on the model, when the worst case altitude and azimuth angles corresponding to ashading problem have been measured. The result of shadow analysis on Dec 21 shows that modules receive

direct beam sun only if distance between two PV strings is maintained at 1m.

Temperature

Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Yearly

avg

Ta (C) 25.5 25.9 27 28.8 27.7 26.7 26.7 26.9 28.3 30 28.5 27.3 27.56

Table 22.1.3-Temperature(Source Meteonorm and PVsyst)

The annual average temperature is 27.56C, with a maximum of 30C and a minimum 25.5C. The maximumannual temperatures are registered in October, while the minimum annual are registered in January.

The operating temperature of solar cells is determined by the ambient air temperature. The open circuit

voltage of each solar cell reduces by 2.3mV with every 1C rise in temperature.


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Wind

The annual average wind speed is 3.2 m/s, with the average maximum speed being 4.0 m/s and the average

minimum speed being 2.6 m/s.

Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Yearly avg

m/s 3 3.5 3.5 3.5 3.1 3.6 4.0 3.6 2.6 2.6 2.6 2.6 3.2Table 22.1.4-Wind (Source Meteonorm and PVsyst)

The operating temperature of solar cells is determined by wind velocity. Further design of structural

component for mounting PV module also depends on wind velocity.

All components such as inverter, converter, and structural components including PV system will be designed

considering above weather data.

22.1.2 Proposed Technology

Solar Photovoltaic (SPV) plants produce electricity by converting the visible part of solar radiation/photons

striking solar cell into direct electricity. The direct electricity is then supplied to inverter through cables and

switchgear, which inverts DC into AC. With 20 tilt of solar module w.r.t horizontal axis the output can be

increased by approximately 8.1%.

Overview Solar Cell technology

Several approaches are used to classify solar cells. One approach is the type and structure of light absorbing

material used, such as single crystal, polycrystalline or amorphous. Device can also be categorized with respect

to the number of junctions used in the cell: single junction and multi junctions or tandem arrangements.

Depending upon the type of light absorbing material used, solar cell technology is broadly classified into silicon

based technologies and compound semiconductor based technologies. The most commonly used technologies

include crystalline silicon cells, multi-crystalline silicon cells. Thin film products, such as amorphous silicon cells

deposited on a substrate, thin film cadmium telluride (CdTe) cells deposited on glass, thin film copper indium

diselenide deposited on glass and other emerging technologies such as organic cells.

Figure 22.1.4--Flow Chart

Using crystalline technology, where individual cells produce dc voltages of approximately 0.5V and dc currents

in the range of one to eight amps takes a large number of cells to produce appreciable amounts of voltage and

power. Usually, PV cells are grouped into series strings of 36 or 72 cells to produce open-circuit voltages of

approximately 20 to 45V.

Solar Cell

Wafer based

Silicon

Thin film

A- Si sheet

/ribbon Si

CdTe, CIS,

CIGS

Mono-

Crystalline

Poly-

Crystalline


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Parameters influencing photovoltaic system operation

Photovoltaic module performance is characterized by its open circuit voltage (Voc), short circuit current (Isc),

maximum power voltage (Vmp) and maximum power current (Imp). Temperature and irradiance are the major

parameters influencing the PV system operation.

Effect of temperature on voltage of photovoltaic module

The open-circuit voltage Voc of an individual silicon solar cell reduces by 2.3mV for every one-degree rise in

temperature T of the solar cell. Therefore, the voltage coefficient is negative.

Effect of temperature and irradiance on the current and voltage of photovoltaic module

The short circuit current Isc of a module is proportional to the irradiance. Therefore, short circuit current

varies continuously in a day. Voltage is a logarithmic function of the current, which varies linearly with

irradiance. Therefore in a day, voltage varies less than the current with irradiance. Figure 3.2 shows a typical

relationship between module current and module voltage for different levels of sunlight incident on a PV

module and temperature.

Figure 22.1.5-Typical relationship between module current and module voltage

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.

Interconnection of Photovoltaic modules

Modules are interconnected to constitute PV array/PV generator. These interconnections have suitable bypass

and blocking diodes. These diodes protect the modules and prevent the PV generator to act as a load when

not irradiated. The modules are connected in series or in parallel depending on the voltage and current

requirement at the output.


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Overview Inverter technology

Power obtained from the solar cell in a day varies with the irradiance level. If the cells terminals are

connected to a variable resistance, the maximum power from the solar cell is obtained at a particular

operating point called MPP. The voltage and current at MPP are known as a Vm and Im. The operating point

will be determined by intersection of the I-V curve of solar cell and load line.

Figure 22.1.6- Graph of Voltage Vs Current

Therefore it is always desirable to connect the inverter in way that it will always work under the MPP.

Further grid interactive inverters can be coupled to an external medium voltage transformer to accommodate

long distance power feeds to distribution substations and delivers the highest efficiency available for large PV

inverters. A user interface features a large LCD that provides a graphical view of the daily plant production as

well as the status of the inverter and the utility grid. An inverter is considered utility interactive provided that

it meets the requirements of IEEE 1547 and is listed to UL 1741. These standards ensure that the inverter

output waveform has less than 5% total harmonic distortion (THD) and that the inverter will disconnect from

the grid if grid power is lost. Once disconnected, the inverter will continue to sample the grid voltage. After the

grid voltage has again stabilized, and after a required five-minute delay, the inverter will reconnect to the grid

and deliver power from the PV system.

System specifications

PV module

1.

Electrical Specification

a.

PV system incorporates polycrystalline silicon technology.

b.

Efficiency of solar module will not be less than 13% with Anti-reflective front surface coating.

c.

Wattage of each PV module is 175W.

d.

Each PV module is configured for 24VDC system voltage.e.

Power temperature coefficient will not exceed -0.5%/C.

f.

Electrical parameters tolerance will not be greater than +/-5%.

g.

Each module will be rated for maximum system voltage upto 1000VDC.

2.

Mechanical Characteristics

Will be extremely light weight with per sqm weight not exceeding 13kg.

a.

Each solar module will be provided with EVA (ethylene vinyl acetate) encapsulant.


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b.

Each solar module will be provided with Anodized Aluminum frame to protect the module.

c.

The front cover will be of high transmissivity, low-iron tempered glass transparent to solar

radiation, easily cleanable and would not allow the temperature of the cells to go high.

d.

The back of the module will be covered with a layer of tedlar.

e.

Bypass circuitry (Schottky bypass diode) for individual solar module will be provided for higher

shadow tolerance.f.

PV module Terminal box will be IP65 with four terminal connection blocks.

g.

Each module will be provided with grounding holes at minimum two places.

h.

Each module will be provided with mounting holes at minimum 8 places. Mounting holes and

grounding holes will not be same.

i.

PV module will be suitable for temperature upto 85C.

j.

Will be suitable for installation on having slope between 3 and 60.

k.

Panels will be 1/4"thick and capable of withstanding all loading requirements.

Grid Tie Inverter

1.

The DC to AC Power Inverter will be 1-phase, 50Hz, 415VAC, Six (6) 4KW.

2.

The MPP operating range will be between 125VDC 600VDC.3.

The inverter will be a grid-interactive, non battery-based, IP65, operating temperature range: -

25C to +70C with maximum power point tracking capability.

4.

The inverter peak efficiency will not be less than 93%.

5.

The Inverter will be designed to accept the PV array output and will be listed to UL1741, IEEE

1547, standards and shall be acceptable to the local utility. The inverter shall start, synchronize,

operate, and disconnect automatically without the need for user action or intervention.

6.

The inverter will have the following protective functions: AC over/under voltage, AC under/over

frequency, over temperature, AC and DC over current, DC over voltage, network islanding.

7.

Inverter will be provided with LCD display, RS485 communication.

Cables and Conduit

1.

Exterior and interior conduit associated with the PV system will be of appropriate inside diameter

for the number and size of wires to be run.

2.

Exposed PV module wiring will be kept to a minimum, will be properly rated for sunlight

resistance, will be properly rated for the hot temperatures associated with the PV array (120

degrees C Insulation) and will be properly secured to avoid physical damage. Means of securing

exposed wiring will be sunlight resistant and able to withstand expected environmental factors

over the life of the system.

3.

DAS signal wire will meet all the DAS manufacturer's guidelines and will not be run in the same

conduit as electrical power wiring.

4.

All cables will be UL listed, new, stranded copper, XLPE insulation and continuous for each

wiring run.5.

Insulation will be rated for 1.1KV.

6.

Power cables will be sized for a voltage drop of 2% or less between PV modules and inverter.

Switchgear

Utility Interconnection

1.

An AC utility disconnect MCCB will be installed in accordance with the utility requirements


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between the PV Panel (PVP) and the point of utility interconnection.

PV Circuit Combiners

1.

Each of PV circuit combiners will be designed and rated to combine series strings of photovoltaic

panels.

2.

The protection of PV circuit will consist of DC MCBs rated for voltage and current not less than

each series string rating.3.

Each Circuit combiner will be provided with surge suppression device.

Inverter DC Input

1.

DC disconnects will be designed and rated for DC power disconnecting (under load) the combined

output of series strings of PV modules.

2.

Each DC disconnect will be provided with surge suppression device.

Monitoring System

1.

The monitoring system will be designed for use with 415 VAC 3 phase power and 450VDC power.

2.

The sensors will measure Ambient Temperature, Module Temperature, Wind Speed, and Plane-

of-Array Irradiance.

3.

Sensors will measure current, voltage, and power in kilowatts (kW) and energy in kilowatt-hours

(kWh) on both the AC side and the DC side.

4.

The monitoring system and associated software will be Web-based.

5.

The monitoring system will sample required parameters at least 30 times per minute and log 15-

minute averages.

6.

Monitoring system web based software is designed to capture data from the data logger and

display it in an informative and educational format.

Structural Components

1.

Anodized aluminum will be used as structural components.

2.

The structure will be rated for maximum wind load of 120mph.

3.

The structure will be designed to support panels weight not less than 200kg with dimensions not

less than 5.2m x 3.4m.

22.1.3 Maintenance and Operation

Photovoltaic system is a safe and reliable power conversion device which can provide many years of

safe dependable performance.

1.

Wash PV array, during the cool of the day, when there is a noticeable buildup of soiling deposits,

cleaning maintains system efficiency and promotes the long-life, high output.

2.

Periodically inspect the system to make sure all wiring and supports stay intact.

3.

Maintain a log of these readings so you can identify if the system is performance is stayingconsistent, or declining too rapidly, signifying a system problem.

Estimation of power Output

The Energy yield analysis, loss diagram, system performance ratio, system configuration for each

system (25KWp) is done using PVsyst software; results of same are shown in Figures below.


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( Source: PVsyst output)


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h l d


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