Solar power is the conversion of energy from sunlight into electricity,
either directly using photovoltaics (PV) or indirectly using concentrated
solar power. Photovoltaic cells convert light into an electric current using
the photovoltaic effect. Concentrated solar power systems use lenses or
mirrors and solar tracking systems to focus a large area of sunlight to a hot
spot, often to drive a steam turbine.
Photovoltaics were initially solely used as a source of electricity for small
and medium-sized applications, from the calculator powered by a single solar
cell to remote homes powered by an off-grid rooftop PV system. Commercial
concentrated solar power plants were first developed in the 1980s.