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Solar panel payback calculator (UK)
Estimate your yearly saving, export income and payback time for a home solar PV system, based on your region, roof direction and electricity price.
Defaults from our data file, last updated 2026-10-20.
Estimates only, not financial advice. Results use average UK figures and the assumptions shown. Your real costs depend on your home, tariff, region and installer quotes. Always get several quotes from certified installers and check current tariff rates before deciding.
How this calculator works
Solar panels save you money in two ways. Every unit (kWh) you generate and use yourself is a unit you don't buy from your supplier, so it is worth your full electricity price. Every unit you don't use flows to the grid and earns your export rate under the Smart Export Guarantee (SEG). The calculator multiplies your system size by a typical yearly yield for your region, splits the result into "used" and "exported", and values each part at the rates you enter.
It then adds those yearly savings together, allowing for panels losing about 0.5% of their output each year, until they cover the installed cost. That point is the payback time. The 25-year figure is the total saving over a typical panel warranty period minus the upfront cost. It does not include inverter replacement (often needed once, at around year 10–15) or any change in electricity prices, which could push the result either way.
The default figures and where they come from
- Electricity price: the Ofgem price cap average for Direct Debit customers from 1 October to 31 December 2026 is 26.32p per kWh. There is no VAT on electricity between 1 October 2026 and 31 March 2027, and that is already reflected in the figure. Your own rate may differ by region and tariff, so check a recent bill.
- Regional yield: a south-facing, roughly 35° roof in south-west England produces around 1,000 kWh per kWp per year, falling to about 760 kWh in northern Scotland. Our figures are rounded from the EU's PVGIS irradiance tool and are approximate. East or west roofs produce about 15–20% less.
- Self-use: households without a battery typically use 30–50% of their solar directly. You'll use more if someone is home in the day or if you run the washing machine, dishwasher or EV charger at midday.
- Export rate: 12p per kWh is a common rate from several large suppliers as of October 2026 (for example Outgoing Octopus, which needs an Octopus import tariff). Basic SEG tariffs pay as little as 3–4.1p, and some installer-linked deals pay 18p or more.
- Cost: £7,000 for a 4 kWp system is our ballpark estimate for a typical installation. Domestic solar is zero-rated for VAT in Great Britain until 31 March 2027. Always use your real quote.
Worked example
A 4 kWp south-facing system in Devon generates about 4,000 kWh a year. If you use half (2,000 kWh), you avoid buying £526 of electricity at 26.32p. The other 2,000 kWh exported at 12p earns £240. That makes about £766 a year, so a £7,000 system pays back in a little over nine years. Swap to a 4.1p export tariff and the yearly benefit drops to about £608, stretching payback to nearly 12 years. That is why choosing the right export tariff matters almost as much as the panels themselves.
How to shorten your payback
- Get at least three quotes from MCS-certified installers. MCS certification is also needed to qualify for most SEG tariffs.
- Use more of your own power. Running appliances on timers in the middle of the day raises the self-use share, which is worth more than exporting.
- Shop around for export rates. You don't have to export to your import supplier, although the best rates often require it.
- Consider a battery carefully. It raises self-use, but adds several thousand pounds. Run the numbers on our solar and battery calculator.
What this calculator can't tell you
Shading from trees, chimneys or neighbouring buildings can cut output sharply, and only a site survey can measure it. Roof condition matters too: if your roof needs replacing in the next decade, doing it first avoids paying to remove and refit panels. Most homes don't need planning permission for roof panels, but listed buildings and conservation areas have extra rules, so check the Planning Portal guidance. Treat our result as a starting point to compare against installer quotes, not as a guarantee.
FAQs
How long do solar panels take to pay back in the UK?
With current prices most well-sited systems pay back in roughly 8–14 years, depending on cost, region, how much you use yourself and your export rate. Our worked example for a 4 kWp south-facing system comes to about nine years.
Do solar panels work in winter?
Yes, but output is much lower. A typical UK system generates around 70% of its yearly total between April and September.
Is there a grant for solar panels?
There is no general national grant in England. Solar panels are zero-rated for VAT until 31 March 2027, and some low-income households may qualify for support through schemes such as ECO4 or local council programmes.
What size system do I need?
Most UK homes fit 3–5 kWp (roughly 8–12 panels). A bigger system usually lowers the cost per kWp, but more of the extra output will be exported at a lower value.
Related calculators
Sources
- Ofgem – Energy price cap unit rates and standing charges (1 Oct–31 Dec 2026)
- European Commission JRC – PVGIS solar irradiance tool
- Octopus Energy – Outgoing Octopus export tariffs
- Smart Export Guarantee rates compared, October 2026 (solarbatterygrants.co.uk)
- HMRC – VAT on energy-saving materials and heating equipment (Notice 708/6)
- MCS – Find a certified installer
- GOV.UK Planning Portal – Solar panels
Estimates only, not financial advice. Results use average UK figures and the assumptions shown. Your real costs depend on your home, tariff, region and installer quotes. Always get several quotes from certified installers and check current tariff rates before deciding.