Photovoltaic cells, also called solar cells, are used to convert sunlight to electricity.
Photovoltaic cells are usually made of layers of single crystal silicon attached by wire. The silicon has semi-conductors on each side. When sunlight hits the silicon, this automatically activates the movement of the electrons and generates electricity.
Since photovoltaic cells do not generate much electricity as single entities, bundles of silicon layers can be bound together to form photovoltaic arrays. These are used for home and office appliances and lights, in addition to streetlights. They can also be used in remote geographical areas that do not have direct access to central power grids.