A photovoltaic (PV) cell is a thin wafer or layer of semiconductor that produces electricity when light falls on it. Most cells are made of silicon. A single cell produces only a small amount of power, so cells are wired together into the solar panels seen on roofs and in solar farms.
How a cell works
A silicon cell has two layers treated with small amounts of other elements, so that one has spare electrons and the other a shortage of them. Where they meet, an electric field forms. When light strikes the cell, its energy frees electrons, and the field pushes them in one direction. Metal contacts on the front and back collect them as a current. The cell produces direct current (DC), which an inverter converts into the alternating current used in homes and on the grid.
Main types
| Type | What it is | Typical features |
|---|---|---|
| Monocrystalline | Cut from a single silicon crystal | Uniform black look; the most common type in new panels |
| Polycrystalline | Cast from many silicon crystals | Blue, speckled look; slightly less efficient and now less common |
| Thin-film | Very thin layers of materials such as cadmium telluride or amorphous silicon on glass or flexible backing | Lighter; lower efficiency per square metre |
Newer designs, such as perovskite and tandem cells, are still moving from the laboratory towards mass production.
Cell, module and array
A cell is the single unit. A module, or panel, is a set of cells wired together and sealed behind glass in a frame. An array is a group of modules connected together, from a dozen on a house roof to hundreds of thousands in a solar farm. Panels are rated in watts, and systems in kilowatts peak.
UK picture
DESNZ puts UK solar PV capacity at 21.9 GW at the end of 2025, after a record 269,000 new installations that year. Solar generated a record 20.1 TWh in 2025, helped by the sunniest year in its records since 2001.
Read more: Solar panels for your home in the UK: costs, savings and how they work.