About Solar Payback
An independent UK guide that answers two questions clearly: will solar panels pay for themselves, and are you being paid fairly for the power you export?
Why this site exists
Most solar calculators are run by companies that sell panels. This one isn't. It's run by an independent UK writer, isn't linked to any installer or energy supplier, and uses today's electricity price for your region every time you visit.
How we calculate
- Electricity made a year = system size (kW) × typical yearly output per kW for your region.
- Saving from using it yourself = electricity you use from your panels × today's electricity price.
- Export earnings = electricity you export × your export rate.
- Payback = cost ÷ yearly saving.
- 25-year profit = yearly saving over 25 years, with panels losing about 0.5% of output each year, minus the cost. It doesn't include future price changes or replacing the inverter.
Where prices come from
We load today's electricity unit rate for your region from Octopus Energy's public tariff data (its standard variable tariff, paying by Direct Debit), which follows the Ofgem price cap. If it can't load, we use the price cap average of 26.32p per kWh from 1 October 2026. We are not affiliated with Octopus Energy.
Key figures and sources
| Figure | Value we use | Source |
|---|---|---|
| Cost of a 4.5 kW system | about £7,600 | Energy Saving Trust figures via Which? |
| Yearly output per kW | 800 to 1,050 kWh by region | Reonic regional yield table |
| Share of solar power used at home | 20–40% without a battery, 60–80% with one | OpusFlow |
| Export rates | 1p to 16p per kWh | SunSave export tariff list (updated 16 September 2026) |
| Typical payback | around 9 to 12 years | Utilita |
Spotted a mistake?
Rules and rates change. We'd rather be corrected than wrong. Get in touch.