EE 235/NSE 203Solar CellsProf. Connie Chang-Hasnain263M Cory HallEECS Department3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 20092Guidelines for Class Presentation• Each person will give two presentations: each 7 min + 3 min Q&A.• Need 17 presentations for next Monday 3/2 on solar cells.• Graded by your peers – 1: Excellent (i.e. I have learned something)– 2: OK (i.e. clear presentation)– 3: Lack of preparation or understanding• By 2/25 (5 days before your presentation)– email Vadim and me a paper or a set of papers you want to review.• By 3/1 (1 day before presentation)– Email Vadim and me your presentations3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 20093Absorption in SemiconductorAssuming is indepent of k; Fv=1 and fc=0 Efc=Efv=Efmris effective reduced mass3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 20094Loss in Semiconductor3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 20095Gain in Semicond.3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 20096Outline• Overview of energy demand• Photovoltaic (solar cell) principles• Solar concentration• High efficiency multi-junction cells• Summary3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 20097World Energy Production Millions of Barrels per Day (Oil Equivalent)30020010001860 1900 1940 1980 2020 2060 2100Source: John F. Bookout,“Two Centuries of Fossil Fuel Energy” International Geological Congress, Washington DC; July 10,1985. Episodes, 12, 257-262 (1989). 3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 20098US CO2Emissions 20050100200300400500600Residential Commercial Industrial Transportation Electricity GenerationMillions of tonnes per year Carbon equivalentNatural GasPetroleumCoalLDVsTrucks BusesAirSource: U.S. EPA Inventory of Greenhouse Gas Emissions, April 20073/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 20099Electric Power Generation• Solar is microscopic. Why?103104105106US Electricity Generation (GWh)2004200220001998199619941992YearWindGeothermalHydroelectricNatural GasNuclearCoalTOTAL Solar Solar source of data: Energy Information Administration3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 200910Cost of Electricity Source: J. Weyant, Energy Modeling Forum, Stanford UniversityLevelized Cost Comparison for Electric Power GenerationWith $100 per Ton Tax on Carbon (2008 Fuel Prices)00.050.10.150.20.250.30.35Nuclear Coal Gas CC Gas CT Solar PV SolarThermalWindGeneration TechnologyCarbon TaxFuel-2008Variable O&MFixed O&M ChargesCapital Charges$/KWHr(2008$s )3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 200911Source of Energy in US• Coal-32%• Natural Gas-30%• Oil-18%-for transportation• Nuclear-12%• Hydropower-5%• Renewable-1%3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 20091205101520253035404550OilCoalGasFissionBiomassHydroelectricSolar, wind, geothermal0.5% Source: BP & IEA2004The ENERGY REVOLUTION(The Terawatt Challenge)14.5 Terawatts220 M BOE/dayThe Basis of Prosperity20stCentury = OIL05101520253035404550OilCoalGasFusion / FissionBiomassHydroelectricSolar, wind, geothermal205030 -- 60 Terawatts450 – 900 MBOE/day21stCentury = ??3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 200913165,000 TW of sunlight hit the earthOur Energy Challenge2004 6.5 Billion People14.5 Terawatts2050 ~ 10 Billion People30-60 TerawattsNeed to convert 0.025 %of incident solar energy3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 200914http://www.nd.edu/~pkamat/energyconversion.html3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 2009152006 Market Summary• World wide installations reached 1.7 GW with 19% growth rate.• Global industry revenues were $10.6 bn in 2006, while capital investmentthrough the PV business chain equaling $2.8 bn.• Over $4 bn in equity and debt financing, up from $1.8 bn in 2005. Marketbuzz™ 2007: ANNUAL WORLD SOLAR PHOTOVOLTAIC REPORT 3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 200916Primary Applications for PV Systems Off-grid Domestic: typically around 1 kW and 1-2 km from power lines.Grid-connected centralized: for power stations. Off-grid nondomestic:The first commercial, terrestrial application. PV are commerciallycost competitive with other sources.TRENDS IN PHOTOVOLTAIC APPLICATIONSSurvey report of selected IEA countries between 1992 and 2005; Report IEA-PVPS T1-15:2006Grid-Connected Distributed:Public and commercial buildings, motorway sound barriers, 1-100kW3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 200917Cumulative Installed PV Power(International Energy Agency countries)• Grid-connected is 3.7 GW or 86% of total. (IEA 2006 report)• Off-grid non-domestic and domestic are 8.4% and 5.5%.3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 200918Competing Technologies• Flat Panel Silicon– Simple arrays of large-area PV cells, fixed at latitude tilt– Cost is dominated by the cost of high-quality mono-crystalline silicon– Polycrystalline Si is cheaper than single-crystal, but is also less efficient– Single Crystal 17-18% (SunPower)– Poly Silicon 14-16% (Kyocera)• Thin-Film– Fixed flat-panels – Lowest cost per watt, but efficiency is much lower thus requiring 2-3 times larger area for same power output. – CdTe Thin Film 10 % (First Solar)– CIGS Thin Film 14 % (e.g. NanoSolar)• Concentrator CPV – Dramatically reducing the area of semiconductor through high concentration (200-1000X) – Requires precise 2-axis tracking– Si Single Crystal 18% (Amonix)– III-V Multi-Junction 22.5% (Concentrix)Note: Percentage figures are best estimates of module efficiency3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 200919History of PV Efficiency (Research Cells)3/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 2009203/1/2009Prof. Chang-Hasnain EE 235/ NSE 203 Sp 200921Current Research Directions• CIGS– Can be deposited on flexible material low cost– Conversion efficiency is similar to that of silicon (~20%)• Multijunction– Higher power conversion efficiency – Higher cost• Polymer – Inexpensive (disposable ?)– Less reliable (degrade over time)– Low power conversion efficiency• Nanocrystalline solar cells– Conversion efficiency achieved so far: 3%– Still at its infancy, but there
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