Panels & output
How do solar panels work? The plain-English version
Solar panels turn light directly into electricity, with no moving parts and no fuel. The physics has been understood for over a century; the engineering is what's become cheap enough to put on roofs and balconies.This guide explains the chain from sunlight to socket in plain English. For the plug-in-specific version, see how plug-in solar works.
Written and edited by Christopher Panteli
Christopher is the founder and editor of MyPlugInSolar. He oversees the site’s research standards, data tools and editorial process. He is not an electrician or solar installer, and specialist technical claims are sourced from official documentation or reviewed by appropriately qualified professionals.
The photovoltaic effect, simply
A solar cell is a thin sandwich of silicon treated so that one layer has spare electrons and the other has spaces for them. When light hits the cell, it knocks electrons loose, and the cell's built-in electric field pushes them in one direction — through whatever circuit you connect. That flow is DC electricity. More light means more electrons moving; that's the whole trick. It's driven by light rather than heat, which is why panels work on cold, bright days — in fact they run slightly more efficiently when cool (see solar panel efficiency).
From cell to panel to your plugs
One cell produces little on its own, so dozens are wired together under glass to make a panel, and panels are wired together to make a system. The output is DC, but homes run on AC — so every system includes an inverter to convert it. On a house, that means panels on the roof, an inverter (central or micro, per panel), and a connection into the consumer unit; the home draws solar first and grid for the rest, exporting any surplus — see grid-tie inverters. A plug-in system is the same chain shrunk down: one or two panels, a microinverter, and a lead — though plug-in use is not yet legal in the UK.
What changes the output
For what this adds up to at your postcode, the calculator turns these factors into an annual estimate.
- Light intensity: output scales with how much light lands on the panel — strongest around midday, lower in cloud, zero at night.
- Direction and tilt: how squarely the panel faces the sun — see direction and angle.
- Shading: even partial shade cuts output sharply — see shading.
- Season: UK winter days are short and dim — see solar in winter.
- Temperature: very hot panels lose a little efficiency.
Frequently asked questions
- Do solar panels work on cloudy days?
- Yes — they run on light, and daylight gets through cloud. Output is reduced, often substantially under heavy cloud, but it doesn't stop. UK solar economics are built around this: systems are sized and estimated using long-run local weather data.
- Do solar panels need direct sunlight?
- No. Direct sun produces the most electricity, but panels also generate from diffuse light scattered by clouds and the sky. That's why orientation and shading matter more than chasing perfect sunshine.
- Do solar panels store electricity?
- No — panels generate in the moment. Storing it needs a battery, which is a separate component; see our solar battery storage guide.
Sources
- 1. PVGIS (Photovoltaic Geographical Information System) — European Commission, Joint Research Centre
Estimate your solar potential
See how much electricity a small system could generate at your postcode, and the indicative bill saving.