SOLAR PVThe 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

• 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)

  USA

  US$/Watt

Feb2007

4.88

Jan2007

4.88

Jan2006

4.71

Jan2005

4.43

Jan 2004

4.45

Jan2003

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.P = 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