Photovoltaics is the direct conversion of sunlight to electricity using semiconductor technology. Current solar cells convert approximately 15-20% of the incoming solar energy into electricity. PV technology employs layers of micro-fine crystalline silicon to convert ordinary sunlight into small electrical charges, this process is then multiplied thousands of times over. A single PV cell consists of two or more thin layers of semi-conducting material, most commonly crystalline silicon. When the silicon is exposed to light, small electrical charges are generated and conducted away by metal contacts as direct current (DC). To maximize energy collection and conversion, single cells are connected together and housed in a module. Modules are in turn, connected together to generate usable volumes of electricity, an inverter is also used to convert high voltage DC into lower voltage AC power.
There are essentially two types of PV module cell technology, monocrystalline and polycrystalline. Crystalline can again be broken down into two types:
Monocrystalline Cells These are made using cells cut from a single cylindrical crystal of silicon. While monocrystalline cells offer the highest efficiency (approximately 18% conversion of incident sunlight), their complex manufacturing process makes them slightly more expensive.
Polycrystalline Cells These are made by cutting micro-fine wafers from ingots of molten and recrystallized silicon. Polycrystalline cells are cheaper to produce, but there is a slight compromise on efficiency (approximately 14% conversion of incident sunlight).