Photovoltaic Systems Engineering Ali Karimpour Associate Professor Ferdowsi University of Mashhad Reference for this lecture Mrs. Golmakanion Thesis Feb 2010 Ferdowsi University of Mashhad
lecture 2 Lecture 5 Photovoltaics Photovoltaics (PV) = Solar Cells. Photo + Voltaic = Convert Light to Electricity. In the term of Power : from mw to MW MW. Efficiency : From less than 10 10% % to more than 40 40% %. 2
History lecture 2 1839 French scientist Edmond Becquerel discovers the photovoltaic effect. 1876 William Grylls Adams and Richard Evans Day discover that selenium produces electricity when exposed to light. 1954 Photovoltaic technology is born in the United States. 1959 On August 7, the Explorer VI satellite is launched. 1972 The Institute of Energy Conversion is established to perform research and development on thin-film photovoltaic. 3
در 5 کشور نخستPVنمودار رشد تجمعی سیستم هاي lecture 2 Chart Title Cumulative Installed Photovoltaic (PV) Power GW 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 Germany Spain Japan US Italy 0.0 1996 1998 2000 2002 2004 2006 2008 2010 Year 4
در 5 کشور انتهاي جدولPVنمودار رشد تجمعی سیستم هاي Chart Title 10.0 9.0 Installed Photovoltaic (PV) Power MW 8.0 7.0 6.0 5.0 4.0 3.0 2.0 Denmark Turkey Finland Bulgaria Norway 1.0 0.0 1996 1998 2000 2002 2004 2006 2008 2010 Year 5
lecture 2 Installed PV Power at the end of 2009 (GW) Germany 0.3 GW 0.36 GW 0.36 GW Spain 2.3 GW Japan 0.46 GW US 0.52 GW 9.7 GW 1.2 GW Italy Korea 1.6 GW Czech Republic Belgium 2.6 GW France China 3.4 GW Rest of World 6
PV Physics 7
Solar Cell Operation lecture 2 Antireflection coating - + External Load 8
PV Advantages Consumes no fuel. No pollution. Wide power-handling capabilities. High power-to-weight ratio. No moving parts. No noise. Lifetimes of 20-30 years or more. 9
Solar Cell Operation lecture 2 10
Equivalent circuit of solar cell hν RL IL RL 11
Equivalent circuit of solar cell 12
Equivalent circuit of solar cell I I I sc BV A( e 1), where A, B, and esp I sc Increasing solar insolation I m Maximum power point Pmax V m I m 0 0 V m V oc V 13
First Generation, Crystalline material Single-crystalline Silicon: Have in the past dominated PV market. Often made using Czochralski process. Best efficiency 25%,Commercial 18% ( NREL). very robust in their stability & reliability. operate well in harsh conditions over several years. have energy payback 1-2 year(s). Expensive. Complex processing & need for large amount of purity silicon. The wafer sizes are limited. 14
First Generation, Crystalline material Poly-crystalline Silicone: Made from cast square ingots. Best efficiency 20%,Commercial 14% ( NREL). Higher sales than the mono-crystalline. Easier assembly of poly-crystalline wafer. cheaper cells. Low efficiency. Both : Share 75% of total PV market in 2009 ( GTM Research). Theoretically limitation of efficiency 31% (S.M.Sze) 15
Second Generation,Thin Films material Thin film of semiconductor 1-10 microns compared to 200-300 microns. Made using thin semiconductor films deposited on low cost substrate (glass,metal,plastic,etc). By epitaxial processes such as vapor deposition, sputter processes & electrolytic bath. Very low cost but poor conversion efficiency! 16
Second Generation,Thin Films material Cadmium Telluride (CdTe): p-type made from Cadmium and Telluride. n-type from Cadmium Sulfide (CdS). One of the most promising thin film solar cells. Best efficiency 16.7%,Commercial 10.6% ( NREL). Share 10% of total PV & more than 50% of thin-films solar cells market in 2009 ( GTM Research). Easier to deposit More suitable for large scale production. Challenging : Cd is toxic! 17
Second Generation,Thin Films material Copper Indium Gallium Di-Selenide (CIGS) : Direct-gap polycrystalline P-type semiconductor. Best efficiency 20.3%,Commercial less than CdTe!! ( NREL). Not reliable in considerable heat & humidity Indium are scarce materials Requires expensive vacuum processing 18
Third Generation,Multi-Junctions Cells lecture 2 Stacked p-n junctions on top of each other. Each junction has a different band gap energy so each will respond to a different part of the solar spectrum. Very high efficiencies, but more expensive. Each junction absorbs what it can and lets the remaining light pass onto the next junction. Overall record for electrical efficiency is 42.4%. 19
PV cell, Module, Array 20
Types of PV Systems 1. Stand-alone Systems. 2. Grid-Connected Systems 21
PV Systems,Stand-alone Systems 22
PV Systems,Grid Connected Systems 1. Without Battery 2. With Battery 23