About half the incoming solar energy reaches the Earths 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. Earths 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.
The total solar energy absorbed by Earths 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 Earths non-renewable resources of coal, oil, natural gas, and mined uranium combined. As intermittent resources, solar and wind raise issues.
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
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 photovoltaics. 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
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.
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.
First Generation – Single Junction Silicon Cells89.6% 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.
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
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.
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
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).
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
-- First Generation -- -- Second Generation -- - Third Gen -
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 2030by 2030 8.9% of Global Energy, 1,864 GW Production Capacity, 2,646 TWhElectricity
$/kWh“Grid parity’ where PV $1.35cost are equal toresidential electricity $1.07costs is expected to beachieved first in $0.81southern Europeancountries and then to $0.54move north $0.27 $0.13 ---
Name of PV power plant Country DC GW·h Notes Peak /year Power (MW)Olmedilla Photovoltaic Park Spain 60 85 Completed September 2008Puertollano Photovoltaic Park Spain 50 2008Moura photovoltaic power Portugal 46 93 Completed December 2008stationWaldpolenz Solar Park Germany 40 40 550,000 First Solar thin-film CdTe modules. Completed Dec 2008Arnedo Solar Plant Spain 34 Completed October 2008Merida/Don Alvaro Solar Park Spain 30 Completed September 2008Koethen Germany 14.75 13 200,000 First Solar thin-film CdTe modules. Completed Dec 2008Nellis Solar Power Plant USA 14.02 30 70,000 solar panelsPlanta Solar de Salamanca Spain 13.8 n.a. 70,000 Kyocera panels6 more Spain, 1 US, 1 Avg 12Germany
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 ** 0High Plains Ranch USA 250 550 Monocrystaline silicon from SunPower with tracking **Mildura Solar concentrator Australia 154 270 Heliostat concentrator using GaAs cellspower 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 FPLFlorida Energy, completion date 2010.** * Under construction; ** Proposed
Blessed with almost year-round sunshine, Spains 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
60 MWp photovoltaic park installed by Nobesol with modules from Silikin
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 exportsThe ‘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
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.
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
The Role of Renewable Energy Consumption in the Nations Energy Supply, 2007 (Quadrillion Btu) Consumption ShareTotal 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%
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)
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.
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
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)