Photovoltaics

Photovoltaics (or PV) panels are comprised of cells. Several panels wired together make up a PV array. PV must be pointed at the sun. Power production is reduced when the sunlight strikes the cells at an angle. PV cells are more efficient in cold weather. Commercial PV cells for home power production transform about 10% of the sunlight into electricity. There are experimental and NASA related PV cells which have a much higher efficiency but they are either very expensive or not yet available. Commercial PV cells are not cheap either but they do not make any noise or pollution while producing power. PV output is DC (direct current) and is usually stored in a battery bank. The battery bank can be tapped direct to provide power for pumps, electric motors, and compression cycle refrigeration (which run more efficiently on DC than AC). An “inverter” may also be connected to the battery bank to produce 120VAC (standard wall current) with about a 5-10% reduction in efficiency. Electric systems which are not connected to the grid are called “off grid” or “stand alone”.