Terrace or small roof
3 kWp (about 7 panels), a terrace or small roof
10 to 14 yearsto pay back
Dark marker on the bar: panels last 25 years or more.
- Installed price
- £4,750 to £6,250
- Saves a year
- £370 to £550
3 kWp (about 7 panels), a terrace or small roof
10 to 14 yearsto pay back
Dark marker on the bar: panels last 25 years or more.
4 kWp (about 10 panels), a typical semi
9 to 12 yearsto pay back
Dark marker on the bar: panels last 25 years or more.
Estimates, not quotes. Each bar shows the payback range on a 0 to 45 year scale, with the dark marker at how long the equipment lasts, so a bar that runs past it is a warning. Prices assume 0% VAT (ends 31 March 2027, then 5%). The plug-in payback is our arithmetic on the Energy Saving Trust figures. Full table and method.
Most houses fit 8 to 12 panels, about 3.5 to 5 kWp. Roof space and your own use decide it.
The Energy Saving Trust says panels should last 25 years or more, and that an inverter needs replacing after around 12 years.
Yes, on cloudy days too, only at lower output. The Energy Saving Trust gives solar payback of about 9 years in London and 10 to 11 in Manchester on July 2026 fuel prices.
The Energy Saving Trust says there are no dedicated UK Government solar panel grants. Warm Homes support has been announced, but we have not confirmed current terms for homeowners, so we do not count it.
Last reviewed 7 October 2026.
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