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THIN FILM SOLAR CELLS

HARRY EFSTATHIADIS, PHD

Pt

Carbon

Nanotu

be

5 m

SiO2

Nanoscale

Science

Nanoscale

Engineering

Parallel KYEY8 nanofibrils on graphite

4 nm4 nm

Nano-

Economics

Nano-

Biotechnology

First colleges in the world dedicated to nanotechnology

using an interdisciplinary approach

Mission: Create a financially and technically competitive environment to empower

the nanoelectronics and renewable energy industries with manufacturing

advantages through partnerships.

Faculty: 55

Grad. Students: 300+

Staff: 3000+

Degrees: B.S.,

M.S., Ph.D,

NanoMBA

Colleges of Nanoscale

Science and Engineering

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NanoFab South

$50M, 150Kft2

32K Cleanroom

Completed: 3/04

NanoFab East

$100M, 250K ft2

Completed: 3/09

NanoFab 200

$16.5M, 70K ft2

4K Cleanroom

Completed:

6/97

NanoFab North

$175M, 228K ft2

35K Cleanroom

Completed:

12/05

NanoFab Central

$50M, 100K ft2z

15K Cleanroom

Completed: 3/09

NanoFab Xtension

$365M, 280K ft2

60K Cleanroom

Completion: 12/12

>1,000,000 ft2 of cutting-edge facilities,with >135,000 ft2 cleanrooms

Current expansion to add 250,000 ft2 to support energy and bio programs

Over $17B in investments over last 10 years

CNSE’s World-Class Resources

CNSE Albany NanoTech Complex

E2TAC – Technology Thrusts

Evolutionary Disruptive Revolutionary

Short Term

Market Focus

Industry Driven

Medium Term

Investment Focus

Technology

Driven

Long Term

Policy Focus

Research Driven

H2/Fuel Cells PEM

SOFC*

Nanosupports

Catalysts

Electrodes

Sensors

Advanced Solar Thin film

a-Silicon

CIGS*

Polymer Based

Nanostructures

Energy Efficiency Green Buildings

Monitoring/

Control Systems

Power Electronics/

Power Quality

Ultra-capacitors

*CIGS: Copper Indium Gallium Selenide

**SOFC: Solid oxide Fuel Cell, PEM: Proton Exchange Fuel Cell

E2TAC: Energy and Environmental Technology Applications Center

http://images.search.yahoo.com/search/images/view?back=http://images.search.yahoo.com/search/images?p=energy+efficient+light+bulb+&ei=UTF-8&fr=slv8-msgr&x=wrt&w=200&h=279&imgurl=www.mass.gov/envir/Sustainable/images/EPP_Images/Initiatives_EPP_Bulb.jpg&rurl=http://www.mass.gov/envir/Sustainable/initiatives/initiatives_EPP.htm&size=5.5kB&name=Initiatives_EPP_Bulb.jpg&p=energy+efficient+light+bulb&type=jpeg&no=1&tt=6,982&oid=26fd111038bf8564&ei=UTF-8http://images.search.yahoo.com/search/images/view?back=http://images.search.yahoo.com/search/images?p=energy+efficient+light+bulb+&ei=UTF-8&fr=slv8-msgr&x=wrt&w=200&h=279&imgurl=www.mass.gov/envir/Sustainable/images/EPP_Images/Initiatives_EPP_Bulb.jpg&rurl=http://www.mass.gov/envir/Sustainable/initiatives/initiatives_EPP.htm&size=5.5kB&name=Initiatives_EPP_Bulb.jpg&p=energy+efficient+light+bulb&type=jpeg&no=1&tt=6,982&oid=26fd111038bf8564&ei=UTF-8http://images.search.yahoo.com/search/images/view?back=http://images.search.yahoo.com/search/images?p=fuel+cell+plug+power+gencore&ei=UTF-8&fr=slv8-msgr&x=wrt&w=200&h=294&imgurl=www.plugpower.com/images/press/gencore.jpg&rurl=http://www.plugpower.com/news/details.cfm?prid=177&size=5.4kB&name=gencore.jpg&p=fuel+cell+plug+power+gencore&type=jpeg&no=1&tt=32&oid=cdd0bcc0d647012c&ei=UTF-8

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Ref.: Arun Majumdar

• Greenhouse effect: the heat radiation reflected from the ground is held back by the

greenhouse gases

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Development of the CO2 content in the atmosphere in the last 22 000 years

• The combustion of fossil fuels has contributed to the increase in CO2 in the

atmosphere from 270 ppm to 397 ppm,

• Anthropogenic carbon dioxide (CO2) emissions (i.e., emissions produced by

human activities) come from combustion of carbon based fuels, principally

wood, coal, oil, and natural gas.

Current Energy Challenges

Climate Change

Greenhouse

Gasses (GHG)

(burning fossil

fuels, clearing

land)

Oil Peak

Billi

ons

of

Bar

rels

per

yea

r

The consequences of using fossil fuels lead to global warming and climate change,

which in the scientific community is a well-settled matter

http://images.google.com/imgres?imgurl=http://peakoil.org.uk/national_geographic_peak_oil.jpg&imgrefurl=http://peakoil.org.uk/&h=436&w=300&sz=48&hl=en&start=10&um=1&tbnid=Zn6fUI0xZAARHM:&tbnh=126&tbnw=87&prev=/images?q=peak+oil&um=1&hl=en&rlz=1T4GZHZ_en___US244&sa=N

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• Electricity generation and industrial production

sectors are the biggest contributors of

greenhouse gas emissions.

• Solar is much more expensive than coal,

nuclear or natural gas.

• Solar installed price/watt has declined over the

last few decades, but is still higher than that

required to achieve grid parity.

Introduction

A New Industrial Revolution for a

Sustainable Energy Future

What is the consequence of global warming and greenhouse gas emissions?

“The average temperature rise is 0.8 degrees,” since the beginning of the Industrial Revolution.

In our homes and local weather, we are used to fluctuations of more than 10 degrees. “Who cares about 0.8 degrees?”

The average tells only a small part of the story.

The temperature deviation from the average over summer time follows a Gaussian distribution and can be normalized by the standard deviation.

Since the 1960s, the whole distribution has moved toward higher temperatures, and the distribution has broadened.

http://images.search.yahoo.com/search/images/view?back=http://images.search.yahoo.com/search/images?p=coal+power+plant&ei=UTF-8&fr=slv8-msgr&x=wrt&w=640&h=994&imgurl=www.isgs.uiuc.edu/servs/pubs/geobits-pub/geobit12/assets/abbottbg.jpg&rurl=http://www.isgs.uiuc.edu/servs/pubs/geobits-pub/geobit12/gb12a.htm&size=79.6kB&name=abbottbg.jpg&p=coal+power+plant&type=jpeg&no=2&tt=6,532&oid=81c957fdbe4c56bc&ei=UTF-8

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Northern Hemisphere – Statistical

Temperature Distribution

Evolution over six decades (1950–

2011) of the statistical distribution of

the deviation of local summer

temperatures from their local

average temperatures.

Blue is colder than average,

Red is hotter than average.

The distribution not only moves to

the right, suggesting hotter

temperatures, but also broadens,

and the tails reach 3–5 times the

standard deviation at probabilities

that are an order of magnitude higher

than those six decades ago1. http://www.youtube.com/watch?v=zSHiEawPRiA

Ref.: 1: J. Hansen , M. Sato , R. Ruedy , PNAS 109 ( 37 ), 14726 ( 2012 )

Energy Overview

How much and what forms of energy are used?

– Residential, industrial, transportation

– Supplied by mix of sources, with fossil fuels dominant

NGPL: Natural Gas Pipeline Company of America (NGPL)

http://www.youtube.com/watch?v=zSHiEawPRiAhttp://www.youtube.com/watch?v=zSHiEawPRiAhttp://www.youtube.com/watch?v=zSHiEawPRiA

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Technology - Based Solutions:

Energy efficiency

Renewable energy

Nonpolluting transportation fuels

Next generation nuclear energy technologies

Transition to distributed energy systems coupled with pollution-free energy carriers

Carbon dioxide sequestration

There is no single or simple answer

http://images.search.yahoo.com/search/images/view?back=http://images.search.yahoo.com/search/images?p=energy+efficiency&ei=UTF-8&fr=slv8-msgr&x=wrt&w=100&h=192&imgurl=www.edha.co.uk/images/tech_Energy_Efficiency.jpg&rurl=http://www.edha.co.uk/prof_tech_energy.asp&size=15.1kB&name=tech_Energy_Efficiency.jpg&p=energy+efficiency&type=jpeg&no=8&tt=80,134&oid=4045bb943333c99c&ei=UTF-8http://images.search.yahoo.com/search/images/view?back=http://images.search.yahoo.com/search/images?p=nuclear+plant&ei=UTF-8&fr=slv8-msgr&x=wrt&w=590&h=501&imgurl=www.idph.state.il.us/timeline/1980nuclear.jpg&rurl=http://www.idph.state.il.us/timeline/1980nulear.htm&size=109.2kB&name=1980nuclear.jpg&p=nuclear+plant&type=jpeg&no=1&tt=33,725&oid=9ae377564c9ca450&ei=UTF-8http://images.search.yahoo.com/search/images/view?back=http://images.search.yahoo.com/search/images?p=transportation+fuel&ei=UTF-8&fr=slv8-msgr&b=41&w=250&h=158&imgurl=www.eere.energy.gov/hydrogenandfuelcells/fuelcells/images/focus_fcv_with_windmills.jpg&rurl=http://www.eere.energy.gov/hydrogenandfuelcells/fuelcells/transportation.html?print&size=11.7kB&name=focus_fcv_with_windmills.jpg&p=transportation+fuel&type=jpeg&no=52&tt=9,840&oid=b44109d81ff8e668&ei=UTF-8

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Solar Cells

Solar Energy

What does photovoltaic (PV) mean?

The word 'photovoltaic' essentially means electricity from the energy of

sunlight. First used in about 1890, the word has two parts:

photo, derived from the Greek 'phos' meaning “light”, and

volt, a unit of measurement named for Alessandro Volta (1745-1827), a pioneer

in the study of electricity.

PV modules (solar cells) are unique

directly convert the incident solar radiation into electricity,

no noise, pollution or moving parts,

making them robust, reliable and long lasting

long lifetime (~20 to 25 years)

energy source is free

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Energy Generation

Methods of electricity generation

Most common energy conversion process is:

mechanical energy electrical energy

Source of mechanical power: most commonly is thermal expansion/compression

cycle via a generator; can also use a turbine or other types of engines

Nuclear, solar thermal, coal, gas

Other sources of mechanical power: Hydro, wind, wave or tidal.

Direct conversion process are “new” form of energy conversion, of which light is converted into electricity via the photovoltaic effect is most common.

Other examples: Seebeck effect – heat directly into electricity.

World Solar Power Capacity

In 2014, World solar power capacity reached for the first time 150 GW.

An unprecedented 30 GW was added to the world grid in 2012 alone

No one would have predicted even 10 years ago that we would see more than 150 GW of solar photovoltaic capacity in the world by 2014.

The photovoltaic industry clearly faces challenges, but the results of 2014 show there is a strong global market for solar technology

Ref. mercomcapital.com/reports/MI/Solar/OCT2014

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Nuclear Power

How much electricity does a typical nuclear power plant

generate? How is this compared to solar power?

In 2012, the "average" nuclear power plant in the US generated

about 11.8 billion kWh.

There were 65 nuclear power plants with 104 operating nuclear

reactors that generated a total of 769 billion kWh, or 19% of the

nation's electricity.

Thirty-six of those plants have two or more reactors.

The Palo Verde plant in Arizona has three reactors with the largest

combined generating capacity of about 3.9 GW.

Fort Calhoun in Nebraska had the smallest capacity with a single

reactor at 0.5 GW.

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Global Solar Installation Growth Set to Hit

Three-Year High in 2014

Global PV installations are forecast to rise at the fastest pace in three

years in 2014, exceeding 40 GW and generating installation revenue of more than $86 billion.

Annual solar installations are predicted to expand at a rate of 18% in 2014, reaching 41 GW and marking the end of the solar industry’s two-year slowdown

PV installations will accelerate in 2015 driven by: low system prices, creation of new markets in emerging regions, and continued growth in major countries such as the United States, Japan and

China. Ref. mercomcapital.com/reports/MI/Solar/OCT2014

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Technology Roadmap: Solar

Photovoltaic Energy 2014

Since 2010, the world has added more solar PV capacity than in the

previous four decades. Total global capacity overtook 150 GW in early 2014.

While a few European countries, led by Germany and Italy, initiated large-

scale PV development, since 2013,

China has led the global PV market, followed by Japan and the United

States

China

USA

Regional Production of PV Electricity Envisioned

in the Roadmap

It is envisioned that PV’s share of global electricity reaching 16% by 2050, a significant

increase from the 11% goal in the 2010 roadmap

India

PV Cost - Towards Grid Parity

Lower cost Poly-Si panels support a key goal for solar known as grid parity,

it costs the same to generate power on rooftops as it does to buy it from the

grid.

The current market for solar PV is dominated by silicon SCs, and this technology is

expected to continue to dominate in the residential and commercial rooftop markets

due to higher efficiency and rapidly reducing costs.

There has been a 40% price reduction since the middle of 2009, largely as a result

of the improved supply of poly-Si. - Down to $21/Kgr in 2014

Ref.: Wolden et al.: Photovoltaic manufacturing: Present status, J. Vac. Sci. Technol. A 29„3 (2011)

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Solar Cells – Applying Nanotech

Innovations

• Sun is the ultimate energy source

– Free, essentially unlimited, not

localized

– CO2 free

• 170,000 TW strike Earth's surface any

given hour

– Global energy demand could be

met by covering a small portion of

earth’s surface with solar cells

• Innovations through:

– Lower cost – thinner silicon, thin

film technologies,

nanocrystalline silicon

– Higher Efficiency –

nanostructures, electrodes and

devices

Types of Solar Cells

Inorganic solar cells

Silicon-based

Wafer based (200 m) single and multi-crystalline Si solar cells

Thin film (less than 2 m)

a-Si:H cell (1x)

a-Si:H/a-SiGe:H/a-SiGe:H triple-junction cell (3x)

a-Si:H/nc-Si:H tandem cell (research stage) (2x)

Thick film (2 – 20m) Polycrystalline Si cell (early research stage)

Non silicon-based

CIGS (Copper Indium Gallium Selenide)

CIAS (Copper Indium Aluminum Selenide)

CdTe (Cadmium Telluride)

Organic solar cells1

Dye-sensitized solar cell (DSSC) PCBM/P3HT

Source: Fonash, S. J., “Solar cell device physics ”, 1981

1. MRS Bull. 30 (1) (2005)

PCBM:[6,6]-Phenyl C61-butyric acid methyl ester

P3HT:Poly(3-hexylthiophene-2,5-diyl)

http://images.google.com/imgres?imgurl=http://www.sequoia.co.uk/home_images/silicon_images/Sanyo/Copy of amorton 3.jpg&imgrefurl=http://www.sequoia.co.uk/silicon/manufacturers/Sanyo/Solar_panels.php&h=255&w=340&sz=93&hl=en&start=28&um=1&tbnid=PvIsRT6eSrdlnM:&tbnh=89&tbnw=119&prev=/images?q=silicon+solar+cell&start=20&ndsp=20&svnum=10&um=1&hl=en&rlz=1T4GZHZ_en___US244&sa=N

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Photovoltaic Cell Efficiencies

Multi-junction

Concentrators

Thin Films

3rd Generation

Silicon

CIGS offers lower manufacturing cost while efficiencies are comparable to multi-

crystalline Si based devices

PV Manufacturing Technology

The production of multicrystalline-silicon (c-Si) solar PV modules is set to

dominate PV manufacturing during 2014, with p-type multi c-Si technology

accounting for 62% of all modules produced. Solar PV manufacturers are currently

planning to increase module production by 25% in 2014, to 49.7 GW of modules,

compared to the 39.7 GW of modules being produced in 2013.

http://bit.ly/MercomQ3S

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The solar cell and solar module as basic

components of photovoltaics

Structure of a grid-coupled photovoltaic plant.

An inverter converts the direct current

supplied by the solar modules into alternating

current and feeds it into the public grid

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PV Manufacturers

• Suntech’s breakthrough Pluto technology is already achieving:

• over 18% conversion efficiency on monocrystalline photovoltaic (PV) cells and

• close to 17% conversion efficiency on polycrystalline PV cells in mass

production, well above conventional screen-printed crystalline PV cells.

http://suntech-power.com/

http://am.suntechpower.com/en/technology.html

http://www.youtube.com/watch?v=fZ1SC-vUe_I

Thin Fil - CuInGaSe Device Layers

Typical Materials

Glass or

Stainless

Cu(In,Ga)Se2 (CIGS)

Transparent Cond. TCO

Front Metal Contacts

Anti-Reflective Coating

+

v

Layer Purpose

Mo

p-type absorber

Reflective

Back Contact

Substrate

n-type buffer CdS

i-ZnO

ZnO:Al

Al

Intrinsic

Resistive TCO

MgF2

~1μm

~0.5μm

~0.5μm

~0.1μm Ni

~50nm

2-4μm*

~3mm

Emphasis is given on the deposition of the p-type CIGS absorber layer

*Graph: Not to scale

http://www.youtube.com/watch?v=fZ1SC-vUe_Ihttp://www.youtube.com/watch?v=fZ1SC-vUe_Ihttp://www.youtube.com/watch?v=fZ1SC-vUe_Ihttp://www.youtube.com/watch?v=fZ1SC-vUe_I

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Industry-led consortium with a manufacturing

development facility (MDF) in New York State with

capabilities for collaborative and proprietary activities

Overall investment of $300M over 5 years from DOE,

Industry, NY State – Launched in 2011

Focus on solar PV technology – CuInGaSe2 (CIGS)

thin films – and manufacturing methods

Expertise of primary partners – CNSE, SEMATECH, –

in consortium management, technology development,

manufacturing productivity, and workforce development

Breadth of support – partnership with ~60 companies

and organizations throughout thin film PV industry

supply chain

DOE SEMATECH CNSE

INDUSTRY

The U.S. PV Manufacturing Consortium

Thin-Film (CIGS) Challenges

Technical challenges –

CIGS cell complexity

Fundamental understanding

of materials and processing

(absorber layer, buffer layer,

front/back contacts,…)

Materials composition and integration

Interfaces and impurities

Deposition and processing parameters

Reliability testing and scientific understanding of degradation

High performance, high volume manufacturing equipment

Real time, in-line metrology

Roadmaps, standards, protocols, certifications

Scaling in manufacturing - small-area champion cell to large area

32

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Cell Types: 10cmX10cm glass or metal flexible substrates,

Co-evaporation and Precursor/Selenization

String / Module types:

- Strings via discrete interconnected cells

- Flexible or Rigid modules (form factors

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Components of a PV system

A PV system is made up of several different components. These include:

groups of PV cells called 'modules' (also known as 'panels');

one or more batteries (optional);

a charge regulator or controller for a stand-alone system;

an inverter for a utility-grid-connected system or when alternating current (AC) rather than direct current (DC) is required;

wiring; and mounting hardware or a framework.

How much space would be needed for PV systems to meet the entire world's electricity needs?

The landscape of a world relying on PV would be almost indistinguishable from the landscape we know today. There are three reasons for this.

First, PV systems have advantages over other technologies. They can be put on roofs and can even be an integral part of a building, such as a skylight.

Second, even ground-mounted PV collectors are efficient from the perspective of land use. Flat-plate PV technology is the most land-efficient means to produce renewable energy.

Third, adequate sunlight is ubiquitous and often abundant, and present in predictable amounts almost everywhere.

Solar Cells:

Challenges with Current Technology

Cost of Silicon based solar cells is high and it is fluctuating

Efficiencies need improvement from 17-20% even above 20%

Performance degradation over time and at increased temperatures

Shortage of raw silicon

Current methods of fabrication are equipment intensive and not

based on continuous processing

Many issues need to be overcome before solar cells

will be achieve widespread deployment

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The Need for Technology Development

Production is key cost-driver for variable module costs

Production equipment and process is not available “off-the-shelf”

Production processes and quality are far from optimized

Existing companies have little experience in scaling up equipment for 100 MW - GW scale solar cell manufacture

Ability to leverage know-how from existing industries (semiconductor and Flat Panel Display)

Fuel cell vehicles are twice as efficient as the average gasoline car. Hydrogen

filling is measured in kilograms (kg), so fuel economy is measured in miles per

kilogram.

Since there's approximately the same potential energy in 1 kg of hydrogen as

there is in 1 gal. of gasoline, comparing by prototype's "mpkg" numbers to the

mpg output of an internal-combustion vehicle is roughly equivalent.

Tank Size: 4.2 to 6 kg hydrogen

H2 Price/Kgr: ~ $4 - $5

Application of Fuel Cell Electric Vehicles

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PV and Fuel Cells & the Environment

Schematic of hydrogen economy dream

Ref.: www.uiowa.edu

3-5 minute hydrogen fueling

Key Drivers of the Clean Energy

Future

Technology

Cost

Performance

Demand Growth

GDP and population growth

Urbanization

Demand management

Rebates

Security

Independence

Competition

Resources

Raw materials

Infrastructure

Nonconventional

Supply Challenges

Local pollution

Climate change

Environment

GDP: Gross Domestic Product

http://images.google.com/imgres?imgurl=http://my.neutralexistence.com/images/Green-Earth.jpg&imgrefurl=http://my.neutralexistence.com/ranking_symbols.php&h=299&w=300&sz=41&hl=en&start=20&um=1&tbnid=SsWBfqE1shDZnM:&tbnh=116&tbnw=116&prev=/images?q=green+earth&um=1&hl=en&rls=GBSA,GBSA:2005-24,GBSA:enhttp://images.google.com/imgres?imgurl=http://www.greenpeace.org/raw/image_full/canada/en/photos-and-video/latest/clean-energy-is-the-solution-f.jpg&imgrefurl=http://asiacleantech.wordpress.com/2007/11/15/australias-labor-promised-a1-billion-for-clean-energy-boost-asia-ties-climate-fight/&h=330&w=430&sz=53&hl=en&start=1&um=1&tbnid=Cr4p5sBBjIlukM:&tbnh=97&tbnw=126&prev=/images?q=clean+energy&ndsp=20&um=1&hl=en&rls=GBSA,GBSA:2005-24,GBSA:en&sa=N

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Solar Cells

Reduction in price of polysilicon and capital equipment in

addition to learning experience have been important drivers

of solar module cost reduction.

Thin Film - CIGS

The 100 kW Pilot facility is currently available in Halfmoon,

NY for demonstrating proof of concept ideas -

Demonstrated efficiency by co-evaporation 18.2%

Conclusions

Questions

What are the advantages and disadvantages of PVs

What are other forms of renewable energy?

What is the Greenhouse effect, why it is happening?

What is Parity?

Name some of the solar cell technologies – What is the efficiency

of each technology?

What is the Power of the Global PV installations What are the

key drivers of PV growth

Name some of the PV Industry challenges?