Solar panel payback in the UK
Figures updated 15 November 2026
A 4 kWp system on a south-facing roof costs about £7,121 and pays for itself in 9.5 years in Plymouth and 12.0 years in Glasgow. Where you live sets how much it generates. How much of that you use at home, and what you're paid for the rest, set what it saves.
| City | Output a year | Saving a year | Pays back | Over 20 years |
|---|---|---|---|---|
| Plymouth | 4,364 kWh | £753 | 9.5 years | £7,932 |
| London | 3,936 kWh | £680 | 10.5 years | £6,464 |
| Cardiff | 3,796 kWh | £667 | 10.7 years | £6,206 |
| Birmingham | 3,740 kWh | £631 | 11.3 years | £5,484 |
| Manchester | 3,460 kWh | £615 | 11.6 years | £5,166 |
| Newcastle | 3,612 kWh | £609 | 11.7 years | £5,056 |
| Glasgow | 3,332 kWh | £591 | 12.0 years | £4,698 |
A gas-heated semi using 2,673 kWh of electricity a year (the median for a semi in England and Wales, DESNZ), with a 4 kWp system facing south at 35° with no shade. Each city uses its own MCS output figure and the cheapest tariff available in its region. Electricity prices from April 2027, when VAT is due to return.
What changes the payback
Where you live. The same system makes 4,364 kWh a year in Plymouth and 3,332 kWh in Glasgow, using the figures MCS installers must quote from.
How much you use yourself. The Birmingham home uses 29% of what it generates and exports the rest. Each unit you use saves about 25.6p on the price cap. Each unit you export earns 12.0p on Outgoing Octopus, or 4.1p on Octopus's fixed Smart Export Guarantee rate.
Your tariff. In every city above the best match was Octopus Flux Import, which pays more for exports between 4pm and 7pm.
What it costs
The median installed price for systems up to 4 kW was £1,780 per kW in 2025/26 (Apr 2025 to Mar 2026), from MCS records published by DESNZ. Source.