Research into Photovoltaic Technology began over one hundred years ago in 1873 and this research has continued up to this present day. Photovoltaic systems are solar energy systems that produce electricity directly from sunlight. PV systems produce clean, reliable energy without consuming fossil fuels and can be used in a wide variety of applications. Photovoltaic (PV) cells convert radiation from the sun into electricity. A typical PV cell consists of a wafer of semi-conducting material, usually silicon, manufactured with two electrically different layers. When sunlight hits the cell it excites the electrons within the silicon, creating an electric field across the layers and causing a flow of electricity.