A solar cell uses the photovoltaic effect at a semiconductor junction to convert light into electricity.
Most conventional solar cells use silicon with a p–n junction. When photons strike the material, they transfer energy to electrons and create electron–hole pairs. The junction's electric field separates these charge carriers, producing a voltage that can drive current through an external circuit.
A single cell produces only a small voltage, so cells are connected into modules and panels. Inverters then convert the direct current from panels into alternating current for many household and grid applications. Solar cells generate electricity without combustion, but their output varies with sunlight, shading, temperature, and orientation.
The photovoltaic effect was observed by Edmond Becquerel in 1839. Bell Labs announced the first practical silicon solar cell in 1954. Solar cells are different from solar-thermal collectors: photovoltaic devices make electricity directly, while solar-thermal systems capture heat for hot water, heating, or power generation.