This guide explains how solar panels work on a UK home, from the photovoltaic effect in each cell to the inverter, your consumer unit and the meter that records exports. It also covers what affects how much electricity your panels make.
Quick answer: Solar panels are made of silicon cells that release electrons when light hits them, creating direct current (DC). An inverter converts it to alternating current (AC) for your home. Your appliances use solar power first; any surplus is exported to the grid, and any shortfall is imported as usual.
The photovoltaic effect
Each solar cell is a thin wafer of silicon treated to create an electric field across it. When light strikes the cell, its energy knocks electrons loose. The electric field pushes those electrons in one direction, and metal contacts on the cell collect them as a direct current. This is called the photovoltaic, or PV, effect.
From cells to panels to an array
- A single cell produces around half a volt.
- Cells are wired together into a panel, typically 108 or more half-cells in a modern domestic panel, giving around 30 to 40 V.
- Panels are wired in strings to raise the voltage for the inverter, forming your solar array.
What does the inverter do?
The inverter converts the DC from the panels into 230 V AC that matches the grid. It also tracks the maximum power point, adjusting voltage and current to get the most power from the panels as light changes. Some systems use microinverters on each panel or optimisers with a central inverter.
Where does the electricity go?
- Solar power flows from the inverter to your consumer unit.
- Appliances that are running use it first.
- Surplus flows out through your meter to the grid, recorded as export by a smart meter.
- When the panels make less than you need, the rest comes from the grid automatically.
- With a battery, surplus can be stored for the evening instead of exported.
What affects how much power you get?
| Factor | Effect |
|---|---|
| Orientation | South is best in the UK; east and west produce less but spread over the day |
| Tilt | About 30 to 40° is close to ideal in most of the UK |
| Shade | Even partial shade can cut output; optimisers can help |
| Temperature | Panels are less efficient when hot; cool sunny days are ideal |
| Season | Summer days give several times more output than winter days |
Do solar panels work on cloudy days?
Yes, but output falls. Panels respond to daylight, not heat, so they still produce on bright overcast days, though far less than in direct sun. Our guide to whether solar panels work on cloudy days has typical figures.
What does it mean for your bill?
Every kWh of solar you use yourself replaces a kWh you would have bought, worth 26.32p under the October to December 2026 cap. Exported kWh earn your Smart Export Guarantee rate instead.
Frequently Asked Questions
How do solar panels generate electricity?
Light frees electrons in silicon cells, creating a direct current that an inverter converts to AC.
Do solar panels work at night?
No. They need light, so a battery or the grid supplies power at night.
Do solar panels need direct sunlight?
No, but direct sun gives much more output than cloudy daylight.
What happens to unused solar power?
It is exported to the grid or stored in a battery if you have one.
Checked November 2026 by the Solaxyra Editorial Team. Sources: Energy Saving Trust: Solar panels, US Department of Energy: How does solar work?.