How a Solar Cell Turns Light Into Electricity

Symbolic image: solar panels on a roof · Photo: CC0

⏱ 55 sec read

Solar panels appear on more and more roofs. But how do the dark panels actually make electricity from sunlight? The principle is over a hundred years old and still astonishing.

At the heart is the solar cell, usually made of silicon – the same material as sand and computer chips. When sunlight hits the cell, it transfers its energy to tiny charge carriers in the material and sets them in motion. Because the cell is built so that these charges can only move in one direction, an electric current arises – without moving parts, without noise, without exhaust.

A single particle of sunlight, a photon, knocks out a charge carrier. This happens billions of times at once – and the combined current of many cells becomes usable electricity.

The catch: a normal solar cell converts only about a fifth to a quarter of the sunlight into electricity; the rest becomes heat. Better efficiencies are the subject of intensive research worldwide.

Why it matters to you: understanding how photovoltaics works helps you judge what a system can do – and why it still produces electricity even under a cloudy sky, just less of it.

Own synthesis based on publicly available fundamentals of photovoltaics.

Symbolic image · Photo: "Solar panels on metal roof", CC0, via Wikimedia Commons