Transcript SOLAR PV
SOLAR PV The conversion of solar energy directly into electricity in a solid state device How does it work? • Stream of photons hit panels at a suitable wave length • Hits P-N junction and transfers energy to some electrons creating higher energy level • Produces voltage of 0.5 V and delivers current proportional to sunlight intensity with a max of 3A Materials Used • Most made out of crystalline silicon – Monocrystalline- until recently always used, expensive – Polycrystalline- easier and cheaper than mono, but less efficient • Others include: • CIS- copper Indium diselenide • CIGS- copper gallium diselenide • CdTe- Cadmium telluride ( highest lab efficiency at 17%) Different Technologies • Thin Film- much cheaper but much less efficient (12%) than crystalline silicon • Multi junction- 2+ PV junctions stacked together • Concentrating systems- using mirrors and lenses to concentrate solar radiation • Silicon spheres- tiny polycrystalline spheres, cheap & low grade • Photoelectrochemical cells- not PV b/c its liquids- manufactured on small scale Remote vs Grid Connected • Remote – Runs with a battery for storage – Good for developing countries fridges, water, pumping, lights • Grid Connected – Transforms DC power from PV to AC at a voltage frequency that can be accepted by grid – Debt/ credit meters measure amounts bought and sold to utility More… • Large, grid connected PV power plants – Multi megawatt scale, optimal sunlight sites (africa, cali etc), distributed by grid • Satellite solar power – In space, receive more sunlight, use microwaves to send to earth- too much capital needed • Non- domestic PV systems – Roof top, used on site Costs of Energy USA US$/ Watt • High capital costs, low running costs • Still too expensive • Smaller systems more expensive p/ watt • 1982- 27$/wp VS 2006- $4/wp • 2003- residential system would be approx $8-12,000 per kwp installed (usually 1.5-2kwp) Feb 2007 4.88 Jan 2007 4.88 Jan 2006 4.71 Jan 2005 4.43 Jan 2004 4.45 Jan 2003 4.87 What the future holds… • Growing at a rapid rate • No green house emissions • Must become more efficient (leading is 17%) • Mass production is needed- market isn’t there yet Future Table 45. Annual Photovolataic Domestic Shipments, 1996-2005 Year Photovoltaic Cells and Modules a (Peak Kilowatts) 1996 13,016 1997 12,561 1998 15,069 1999 21,225 2000 19,838 2001 36,310 2002 45,313 2003 48,664 2004 78,346 2005p 134,465 Total 424,807 a Total shipments minus export shipments. = Preliminary. Notes: Totals may not equal sum of components due to independent rounding. Total shipments include those made in or shipped to U.S. Territories. Sources: Energy Information Administration, Form EIA-63B, "Annual Photovoltaic Module/Cell Manufacturers P