How does a solar cell turn light into electricity?

A photovoltaic cell converts energy carried by light into electrical energy. A common cell is made from silicon, a semiconductor. Its electrical behavior can be controlled by adding small amounts of other elements. Two differently treated regions form a junction with a built-in electric field.

An absorbed photon can transfer enough energy to free an electron from its usual bonding role. This leaves a hole, an absence of an electron that acts as a positive charge carrier. Both the electron and hole can contribute to electrical conduction. Some photons are reflected or pass through, and some absorbed energy becomes heat.

The junction’s electric field helps separate light-generated electrons and holes before they recombine. Metal contacts collect charge at the cell’s two sides. When an external conducting path includes a load, electrons can flow through that path and transfer energy to the load. A continuing supply of absorbed light sustains the energy conversion.

The field helps organize charge movement; it is not an extra energy source. The electrical energy delivered ultimately comes from the light. Real cells convert only part of the incoming light power into useful electrical power. Their output depends on light, temperature, materials and the connected circuit.