【正文】 rst practical solar cells with a sunlight energy conversion efficiency of around 6%. ? 1958 First spacecraft to use solar panels was US satellite Vanguard 1 PV Solar for Electricity Photovoltaics ? For the 2 billion people without access to electricity, it would be cheaper to install solar panels than to extend the electrical grid. (The Fund for Renewable Energy Everywhere) ? Providing power for villages in developing countries is a fastgrowing 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 How Solar Cells Work 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. Solar Cells Background 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 mercial production, accounting for % of 2022 production. Solar Cells Background First Generation – Single Junction Silicon Cells % of 2022 Production % Single Crystal Si % Multicrystal SI ? Largearea, 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. ( yr in Europe) ? Single crystal silicon 1619% efficiency ? Multicrystal silicon 1415% efficiency and Solar Generation V Report Sept 08 Silicon Cell Average Efficiency Solar Cells Background Second Generation – Thin Film Cells CdTe % amp。s largest photovoltaic (PV) power plants (12 MW or larger) 1] Name of PV power plant Country DC Peak Power (MW) GWh /year Notes Rancho Cielo Solar Farm USA 600 Thin film silicon from Sig Solar** Topaz Solar Farm USA 550 1,100 Thin film silicon from OptiSolar ** High Plains Ranch USA 250 550 Monocrystaline silicon from SunPower with tracking ** Mildura Solar concentrator power station Australia 154 270 Heliostat concentrator using GaAs cells from Spectrolab** KCRD Solar Farm USA 80 Scheduled to be pleted in 2022 ** DeSoto County, Florida USA 25 To be constructed by SunPower for FPL Energy, pletion date 2022.* Davidson County solar farm USA 36 individual structures** C225。 ** Proposed Spain ? Blessed with almost yearround sunshine, Spain39。s Energy Supply, 2022 (Quadrillion Btu) Consumption Share Total US Coal 22% Natural Gas 23% Petroleum 39% Nuclear Electric Power 8% Renewable Energy: 7% Of which: Hydroelectric 36% Geothermal Energy 5% Biomass 53% Solar Energy 1% Wind Energy 5% US Solar Industry Data ? Size of . Market 2022 . had about 8,800 megawatts (MW) of installed solar capacity. 1,100 MW of photovoltaics (PV), 418 MW of utilityscale concentrating solar power, 485 MWTh (megawatts thermal equivalent) of solar water heating systems 7,000 MWTh of solar pool heating systems. ? Ranking of . Market: Cumulative installed solar electric power by 2022. 1st Germany GW, 2nd Japan GW, 3rd US 814 MW, 4th Spain 632 MW ? Growth of . Market 2022 more than 18,000 individual PV systems were installed. Totaled 342