About SolarSums

Many solar calculators are run by companies that sell or install panels. SolarSums is different. It's a free, independent UK calculator that shows the year a system pays back, or tells you plainly that it doesn't.

We don't sell or install panels, batteries or chargers, and no installer pays to appear in our results. Our numbers come from public sources: PVGIS sun data, live published tariffs and Energy Saving Trust guidance. We show our method in full on How it works.

Our guides are written for UK households and are checked before they're published. When we use an example household, we say so. We aim to update figures when rules change, such as the 0% VAT on installed solar, which runs until 31 March 2027.

Everything on SolarSums is an illustration and general information, not financial advice. Before you buy, get quotes from MCS-certified installers.