1. Photovoltaic Solar Energy

2.  About half the incoming solar energy reaches the Earth's
surface.
 The Earth receives 174 petawatts (PW) (1015 watts) of
incoming solar radiation at the upper atmosphere.
Approximately 30% is reflected back to space while the rest is
absorbed by clouds, oceans and land masses.
 Earth's land surface, oceans and atmosphere absorb solar
radiation, and this raises their temperature. Sunlight absorbed
by the oceans and land masses keeps the surface at an
average temperature of 14 °C.
 By photosynthesis green plants convert solar energy into
chemical energy, which produces food, wood and the biomass
from which fossil fuels are derived.

4.  The total solar energy absorbed by Earth's atmosphere, oceans
and land masses is approximately 3,850,000 exajoules (EJ)
(1018 joules) per year. (70% of incoming sunlight)
(1 Joule = energy required to heat one gram of dry, cool air by
1˚ C)
 Primary energy use (2005) 487 EJ (0.0126%)
 Electricity (2005) 56.7 EJ (0.0015%) Therefore a good target
 2002, more energy in one hour than the world used in the
year.
 Photosynthesis captures approximately 3,000 EJ per year in
biomass.
 The amount of solar energy reaching the surface of the planet
is so vast that in one year it is about twice as much as will ever
be obtained from all of the Earth's non-renewable resources of
coal, oil, natural gas, and mined uranium combined.
 As intermittent resources, solar and wind raise issues.

5.  1839 - French physicist A. E. Becquerel first recognized the
photovoltaic effect.
 Photo + voltaic = convert light to electricity
 1883 - first solar cell built, by Charles Fritts, coated
semiconductor selenium with an extremely thin layer of gold
to form the junctions.
 1954 - Bell Laboratories, experimenting with semiconductors,
accidentally found that silicon doped with certain impurities
was very sensitive to light. Daryl Chapin, Calvin Fuller and
Gerald Pearson, invented the first practical device for
converting sunlight into useful electrical power. Resulted in
the production of the first practical solar cells with a sunlight
energy conversion efficiency of around 6%.
 1958 - First spacecraft to use solar panels was US satellite
Vanguard 1

6. Photovoltaic
 For the 2 billion people without access to electricity, it would be
cheaper to install solar panels than to extend the electrical grid.
 Providing power for villages in developing countries is a fast-
growing market for photovoltaic's. The United Nations estimates
that more than 2 million villages worldwide are without electric
power for water supply, refrigeration, lighting, and other basic
needs, and the cost of extending the utility grids is prohibitive,
$23,000 to $46,000 per kilometer in 1988.
 A one kilowatt PV system* each month:
› prevents 150 lbs. of coal from being mined
› prevents 300 lbs. of CO2 from entering the atmosphere
› keeps 105 gallons of water from being consumed
› keeps NO and SO2 from being released into the environment
* in Colorado, or an equivalent system that produces 150 kWh per month

7. 1. Photons in sunlight hit the
solar panel and are absorbed
by semiconducting materials,
such as silicon.
2. Electrons (negatively charged)
are knocked loose from their
atoms, allowing them to flow
through the material to
produce electricity.
3. An array of solar cells
converts solar energy into a
usable amount of
direct current (DC) electricity.

8. Three generations of solar cells
 Solar Cells are classified into three generations which
indicates the order of which each became important.
 At present there is concurrent research into all three
generations while the first generation technologies are most
highly represented in commercial production, accounting for
89.6% of 2007 production.

9. First Generation – Single Junction Silicon Cells
89.6% of 2007 Production
45.2% Single Crystal Si
42.2% Multi-crystal SI
Silicon Cell Average Efficiency
 Large-area, high quality and
single junction devices.
 High energy and labor inputs which
limit significant progress in reducing
production costs.

10.  Single junction silicon devices are
approaching theoretical limit efficiency
of 33%.
 Achieve cost parity with fossil fuel
energy generation after a payback period
of 5–7 years. (3.5 yr in Europe)
 Single crystal silicon - 16-19% efficiency
 Multi-crystal silicon - 14-15% efficiency

11. Second Generation – Thin Film Cells
CdTe 4.7% & CIGS 0.5% of 2007 Production
 New materials and processes to improve efficiency and reduce cost.
 As manufacturing techniques evolve, production costs will be
dominated by constituent material requirements, whether this be a
silicon substrate, or glass cover.
 Thin film cells use about 1% of the expensive semiconductors
compared to First Generation cells.
 The most successful second generation materials have been
cadmium telluride (CdTe), copper indium gallium selenide (CIGS),
amorphous silicon and micromorphous silicon.

12.  Trend toward second gen., but commercialization has proven
difficult.
› 2007 - First Solar produced 200 MW of CdTe solar cells, 5th largest
producer in 2007 and the first to reach top 10 from of second
generation technologies alone.
› 2007 - Wurth Solar commercialized its CIGS technology producing
15 MW.
› 2007 - Nanosolar commercialized its CIGS technology in 2007 with a
production . capacity of 430 MW for 2008 in the USA and
Germany.
› 2008 - Honda began to commercialize their CIGS base solar panel.
 CdTe – 8 – 11% efficiency (18% demonstrated)
 CIGS – 7-11% efficiency (20% demonstrated)
 Payback time < 1 year in Europe

13. Third Generation – Multi-junction Cells
 Third generation technologies aim to enhance poor electrical
performance of second generation (thin-film technologies) while
maintaining very low production costs.
 Current research is targeting conversion efficiencies of 30-60%
while retaining low cost materials and manufacturing
techniques.
 They can exceed the theoretical solar conversion efficiency
limit for a single energy threshold material, 31% under 1 sun
illumination and 40.8% under the maximal artificial
concentration of sunlight (46,200 suns).

14.  Approaches to achieving these high efficiencies including
the use of multijunction photovoltaic cells, concentration of
the incident spectrum, the use of thermal generation by
UV light to enhance voltage or carrier collection, or the use
of the infrared spectrum for night-time operation.
 Typically use fresnel lens (3M) or other concentrators, but
cannot use diffuse sunlight and require sun tracking
hardware
 Multi-junction cells – 30% efficiency (40-43%
demonstrated

17. -- First Generation -- -- Second Generation -- - Third Gen -

19. Annual PV Market Outlook
$700 Rest of World
$600 South Asia
Sales in Billions
$500 China
$400 Central + South
$300 America
North America
$200 Europe
$100
$-
2007 2010 2015 2020 2025 2030
by 2030 8.9% of Global Energy, 1,864 GW Production Capacity, 2,646 TWh
Electricity

20. $/kWh
“Grid parity’ where PV $1.35
cost are equal to
residential electricity $1.07
costs is expected to be
achieved first in $0.81
southern European
countries and then to $0.54
move north
$0.27
$0.13 ---

21. Name of PV power plant Country DC GW·h Notes
Peak /year
Power
(MW)
Olmedilla Photovoltaic Park Spain 60 85 Completed September 2008
Puertollano Photovoltaic Park Spain 50 2008
Moura photovoltaic power Portugal 46 93 Completed December 2008
station
Waldpolenz Solar Park Germany 40 40 550,000 First Solar thin-film
CdTe modules. Completed Dec
2008
Arnedo Solar Plant Spain 34 Completed October 2008
Merida/Don Alvaro Solar Park Spain 30 Completed September 2008
Koethen Germany 14.75 13 200,000 First Solar thin-film
CdTe modules. Completed Dec
2008
Nellis Solar Power Plant USA 14.02 30 70,000 solar panels
Planta Solar de Salamanca Spain 13.8 n.a. 70,000 Kyocera panels
6 more Spain, 1 US, 1 Avg 12
Germany

22. Name of Plant Country DC GW· Notes
Peak h
Power /year
(MW)
Rancho Cielo Solar Farm USA 600 Thin film silicon from Signet Solar**
Topaz Solar Farm USA 550 1,10 Thin film silicon from OptiSolar **
0
High Plains Ranch USA 250 550 Monocrystaline silicon from SunPower with
tracking **
Mildura Solar concentrator Australia 154 270 Heliostat concentrator using GaAs cells
power station from Spectrolab**
KCRD Solar Farm USA 80 Scheduled to be completed in 2012 **
DeSoto County, Florida USA 25 To be constructed by SunPower for FPL
Energy, completion date 2009.*
Davidson County solar farm USA 21.5 36 individual structures**
Cádiz solar power plant Spain 20.1 36 *
Kennedy Space Center, USA 10 To be constructed by SunPower for FPL
Florida Energy, completion date 2010.**
* Under construction; ** Proposed

23.  Blessed with almost year-round sunshine, Spain's socialist
government is trying to capitalize on this natural resource.
 In an effort to encourage private individuals and
companies to install solar power, Spain introduced
subsidies of €0.42 per kilowatt per hour ($0.57/KWhr)
(‘feed-in’ tariff and off-grid subsidies)
 But the Spanish government is considering reducing this
subsidy in September, a move which is likely to face
opposition from within the solar energy industry.
 2007: 26,800 employees in Spanish solar companies

24. 60 MWp photovoltaic park installed by Nobesol with modules from Silikin

25.  10,000 companies, including installers work in solar PV
 80 companies are cell and module makers
 42,000 employees
 Sales were $5.7 B including $2.5 B in exports
The ‘feed-in’ tariff
 2008 German utilities pay $0.47 to $0.68/kWh depending
on type and size of system for new solar systems
 Utilities pass cost to consumers – Germany average is
$1.65/month

26.  The Waldpolenz Solar Park is built on a surface area equivalent
to 200 soccer fields, the solar park will be capable of feeding 40
megawatts into the power grid when fully operational in 2009.
 In the start-up phase, the 130-million-euro ($201 million) plant
it will have a capacity of 24 megawatts, according to the Juwi
group, which operates the installation.
 The facility, located east of Leipzig, uses state-of-the-art, thin-
film technology. Some 550,000 thin-film modules will be used,
of which 350,000 have already been installed.
 The direct current produced in the PV solar modules will be
converted into alternating current and fed completely into the
power grid.
 After just a year the solar power station will have produced the
energy needed to build it, according to the Juwi group.

29.  2007 - PV production grew in all areas of US market
 US leads development of thin-film technology accounting
for nearly half the global production
 2007 – about 50,000 employees
 CA dominates with 60% of installed capacity
 Various state Renewable Portfolio Standards (RPS) and
Federal Investment Tax Credits (ITC) are incentives.
 Solar America Initiative making progress on goal to bring
PV costs to grid parity by 2015

31. The Role of Renewable Energy Consumption in the Nation's
Energy Supply, 2007 (Quadrillion Btu)
Consumption Share
Total US 101.545
Coal 22.776 22%
Natural Gas 23.637 23%
Petroleum 39.773 39%
Nuclear Electric Power 8.415 8%
Renewable Energy: 6.813 7%
Of which:
Hydroelectric 2.446 36%
Geothermal Energy 0.349 5%
Biomass 3.596 53%
Solar Energy 0.081 1%
Wind Energy 0.341 5%

32.  Size of U.S. Market
2008 - U.S. had about 8,800 megawatts (MW) of installed solar
capacity.
1,100 MW of photovoltaics (PV),
418 MW of utility-scale concentrating solar power,
485 MWTh (megawatts thermal equivalent) of solar water heating
systems
7,000 MWTh of solar pool heating systems.
 Ranking of U.S. Market: Cumulative installed solar electric power by
2007. 1st Germany 3.8 GW, 2nd Japan 1.9 GW, 3rd US 814 MW,
4th Spain 632 MW
 Growth of U.S. Market 2008 - more than 18,000 individual PV
systems were installed. Totaled 342 MW: 292 MW was grid-connected.
 Growth of U.S. Manufacturing 2008 domestic PV cell manufacturing
capacity grew 65 percent to 685 MW and production grew 53 percent
to 414 MW. (Results preliminary) (Source: Greentech Media Research
and the Prometheus Institute)

34.  The largest rooftop solar power station in the world is being built
in Spain. With a capacity of 12 MW of power, the station is made
up of 85,000 lightweight panels covering an area of two million
SqFt.
 Manufactured in rolls, rather like carpet, the photovoltaic panels
are to be installed on the roof of a General Motors car factory in
Zaragoza, Spain.
 General Motors, which plans to install solar panels at another 11
plants across Europe, unveiled the €50M ($68M) project
yesterday. The power station should be producing energy by
September.
 The panels will produce an expected annual output of 15.1
million kilowatt hours (kWh) - enough to meet the needs of
4,600 households with an average consumption of 3,300kWh, or
power a third of the GM factory. The solar energy produced
should cut CO2 emissions by 6,700 tons a year.
 Energy Conversion Devices who makes the panels, said it would
be the largest rooftop solar array in the world.

36.  2002 - Basic Act on Energy Policy to secure stable energy
supply, environmental suitability and use of market
mechanisms
 By 2006, installed 1.2 GW for 350,000 homes
 2008 – New research initiative to improve yields from 10-
15% to 40% and reduce cost from $0.48/kWh to
$0.073/kWh

37.  2007
 National Renewable Energy targets
› 10% by 2010 (300 MW)
› 15% by 2020 (1.8 GW)
 Supplies 1,130 tons of polysilicon from 6 companies
 Supplies 21,400 tons of silicon ingot from 70 companies
 Number 1 PV panel producer – 1.1 GW
 50 PV panel companies including Suntech, Yingli, Hebei
Jingao, Jiansu Linyang, and Nangjing CEEG
 82,800 employees (6 times that of 2005)