Photovoltaic Components

A photovoltaic cell, or solar cell, is a semiconductor device that converts light directly into electricity through the photovoltaic effect. When light strikes the cell, photons with enough energy free charge carriers within the semiconductor, and the built-in electric field of a junction separates them, producing a voltage and a current at the cell’s terminals. Unlike a battery, a solar cell stores no energy; it generates power only while it is illuminated, and its output depends on the intensity of the light falling on it.

Most solar cells are made from silicon, formed into a junction between regions of different doping much like a large-area diode. A single cell produces only a small voltage, so cells are connected in series to raise voltage and in parallel to raise current, then assembled into modules or panels. The current a cell delivers is roughly proportional to the light it receives, while its voltage changes more slowly, so the panel has a characteristic operating curve with a point of maximum power output.

Photovoltaic systems use these panels to charge batteries, run equipment, or supply electricity to a building or the grid. Because the output varies with sunlight and temperature, supporting electronics such as charge controllers and converters condition the power. Solar electricity is valued because it produces no emissions in use and needs no fuel, although the energy available depends on weather, the time of day, and the orientation of the panels toward the sun.

Frequently asked questions

What is the photovoltaic effect?

It is the generation of a voltage and current in a material when it absorbs light. Photons free charge carriers in a semiconductor, and a junction’s electric field separates them to produce electricity.

How are solar cells combined into panels?

Cells are connected in series to increase voltage and in parallel to increase current, then mounted together in a module or panel that produces a useful amount of power.

Does a solar cell store energy?

No. A solar cell generates electricity only while light falls on it. To use solar power when there is no sunlight, the energy must be stored in batteries.