Solar powered electric motor, c 1990s.
© Science Museum / Science & Society Picture Library
This small electric motor is driven by light energy falling on a solar cell. Solar cells work as a result of the photoelectric effect. Instead of pushing electrons out of metal, light falling on a solar cell is used to loosen electrons within a semiconductor, usually silicon. The light energy arrives at the cell in packets, or photons, and these dislodge electrons within the silicon to create the current.