How much do solar panels save?
The honest answer is “it builds up”. See year-one savings for your system size, then the 25-year picture with energy prices rising at an assumed 3% a year.
Figures checked October 2026 Estimate
25-year figures assume energy prices rise 3% per year and panel output holds steady. Real life will differ in both directions — this is a planning estimate, not a forecast.
How much do solar panels save a year?
For a typical 4kWp system generating an estimated 3,400kWh a year, the year-one saving lands between roughly £450 and £700 at October 2026 prices — the low end if you export most of it at ~5p, the high end if you use most of it yourself and avoid buying at 26.32p. Smaller systems save proportionally less; a 6kWp system on a high-usage home can clear £900 in year one. Your own number lives in the two sliders above: system size and, above all, self-consumption.
Over 25 years the compounding matters. Holding prices flat, that 4kWp system returns an estimated £11,000–£17,000. Let prices rise at 3% a year — below the long-run trend of the last two decades — and the same system returns an estimated £16,000–£26,000, against an install cost of £6,000–£8,000 today. That’s why solar is better understood as a hedge than an investment: every price rise after you install is a rise you mostly don’t pay.
What doesn’t show up in the savings figure
Two honest omissions. First, the inverter replacement around year 10–15 (an estimated £800–£1,500) — mentally subtract it. Second, panels degrade around 0.5% a year (estimate), so year-25 output is roughly 88% of year one; the table above ignores this, slightly flattering the total. Set against that: nothing here credits the value solar adds to your EPC rating or saleability, and predictions that need the SEG earnings split out separately can run them through the dedicated calculator.
Savings questions
Why assume 3% price inflation?
It’s a stated planning assumption, not a prediction — roughly in line with long-run energy price trends and deliberately below the spikes of 2022–23. Set the import price lower in the calculator to see the pessimistic case.
Is the saving mostly bills or exports?
Bills, by a wide margin. A unit used at home saves 26.32p; a unit exported earns ~5p. That’s why usage timing and batteries matter more than raw panel count.
Do savings count if I move house?
Panels are usually included in the sale and surveyors increasingly treat them as a feature (better EPC, lower bills). The value added is hard to pin down — one more reason the guide treats savings, not house price, as the payback route.
Ready for real prices?
Calculators give you the ballpark. Get free, no-obligation quotes from MCS-certified UK installers and compare them against these numbers.