Solar is worth it across almost all of the UK — the question is how quickly it pays back, and that varies more by how you use the electricity than by where you live. A typical 4 kWp system costs around £5,600 to fit and, at the Ofgem cap for 1 July – 30 September 2026, pays for itself in roughly 6.5 to 9 years depending on region. After that it is largely free electricity for the rest of a 25-year-plus panel life.
Payback by region
These figures are for a 4 kWp system on a south-facing roof, with half the generation used in the home and the rest exported at about 15p a unit. Yields come from MCS irradiance zones — the same regional figures the industry uses.
| Region | Yield (kWh/kWp) | Annual benefit | Payback |
|---|---|---|---|
| Cornwall & Devon | 1,050 | £863 | 6.5 yrs |
| London & South East | 980 | £806 | 6.9 yrs |
| The Midlands | 920 | £756 | 7.4 yrs |
| North West | 860 | £707 | 7.9 yrs |
| Central Scotland | 820 | £674 | 8.3 yrs |
| Northern Scotland | 760 | £625 | 9.0 yrs |
The spread from top to bottom is only about two and a half years — geography matters, but less than people expect. Even in northern Scotland a system that pays back in nine years still earns you roughly £10,000 over its life. In Cornwall that lifetime figure is closer to £16,000.
The factor that beats geography: self-consumption
Every unit of solar you use at home saves the full 26.11p you would otherwise pay. Every unit you export earns only around 15p. So the more of your own generation you actually use, the faster the payback — and this lever is bigger than the difference between Cornwall and Scotland. A household at home during the day, running the washing machine and dishwasher on a timer for midday, and charging an EV or an immersion heater on sunny afternoons, can push self-consumption from 50% toward 70% and shave a year or more off the payback wherever they live.
Roof direction and shading
A south-facing roof is the benchmark. South-east or south-west loses only about 5%. East or west roofs give up around 20%, which is often still worth it and can suit self-consumption better by spreading generation across morning and evening. A north-facing roof gives up around 40% and rarely pays — that is a genuine no. Shading from trees, chimneys or neighbouring buildings hits output hard, so an honest survey looks at your specific roof, not a regional average.
Should you add a battery?
A battery stores daytime generation for evening use, lifting self-consumption and, on a cheap overnight tariff, letting you buy low and use it at peak. It also adds several thousand pounds and extends the overall payback. For many homes panels alone pay back faster, with a battery added later once the tariff and usage pattern are clear. Worth modelling separately rather than assuming.
When solar is worth it — and when to pause
Solar is worth it if you have an unshaded roof facing anywhere from east through south to west, you use a fair share of your generation at home, and you plan to stay put long enough to clear the payback. Pause if your only roof faces north, it is heavily shaded, or you expect to move within a few years. As ever, the regional figures here are a starting point — put your own region, roof direction and electricity use into the numbers before you commit.