How Do Solar Panels Make Electricity?

A solar panel is not usually a device that first turns sunlight into heat and then spins a turbine. Its photovoltaic cells convert light directly into electricity. A panel contains many solar cells, commonly made with a semiconductor such as silicon. When light reaches a cell, some of its energy is absorbed in the material and gives electrons enough energy to become mobile.

Mobile electrons alone are not yet useful power. A cell is built with semiconductor regions that have been treated to have different electrical properties, creating an internal electric field at their junction. That structure pushes electrons and the corresponding positive charges in different directions. The resulting separation creates a voltage between the two sides of the cell. This is the practical heart of the photovoltaic effect.

Fine metal contacts on the cell collect the moving electrons and lead them into an external circuit. When that circuit is connected, the moving charge is direct current, or DC electricity. One cell produces only a modest amount of power, so manufacturers wire cells together into a weather-protected panel. Panels can then be connected into arrays sized for a calculator, a rooftop, or a power plant.

Homes and most electricity grids use alternating current, so a solar installation normally includes an inverter. It changes the DC from the panels into usable AC. A panel’s output falls when the light is weak and stops at night, which is why a grid connection or a battery serves a different purpose: it helps match available generation with the time electricity is needed.

A solar panel is therefore neither a sunlight-storing battery nor a machine that converts all incoming light into power. Output depends on light intensity and wavelength, the cell material and temperature, shade, and the panel’s orientation. The essential idea is simpler: light sets charges moving in a semiconductor, and the cell’s structure guides that movement into a one-way electric current.