Photovoltaic involves the direct generation of electricity from light by using a semi-conductor material which can be adapted to release electrons.
The most important parts of a PV system are the cells which form the basic building blocks, the modules, which bring together large numbers of cells into a unit, and, in some situations, the inverters used to convert the electricity generated into a form suitable for everyday use.
All PV cells have at least two layers of semi-conductors, one positively charged and one negatively charged. When light shines on the semi-conductor, the electric field across the junction between these two layers causes electricity to flow, generating DC current. The greater the intensity of the light, the greater the flow of electricity.
A photovoltaic system does not need bright sunlight in order to operate. It also generates electricity on cloudy days, with its energy output proportionate to the density of the clouds.