Are solar panels worth it in the UK?
Solar panels can cut your electricity bills and earn money from exported power, but whether they pay off depends on your roof, how much energy you use during daylight, and what you pay to install them. This calculator estimates payback and lifetime return.
Two sources of value
A solar system saves and earns money in two ways:
- Self-consumption: every unit you use yourself avoids buying it from the grid at the full import rate — the biggest saving.
- Export income: surplus power sent back to the grid earns money under the Smart Export Guarantee (SEG), typically 5–15p/kWh depending on supplier.
What a UK roof produces
As a rule of thumb, each kWp of panels generates around 900 kWh a year in the UK, best on a south-facing, unshaded roof. A typical 4 kWp system therefore produces roughly 3,600 kWh — a large share of an average home's electricity. Output is highest in summer and lowest in winter, when demand is greatest.
Why timing matters so much
The economics hinge on how much you use directly. If you're out all day and export most generation at 15p, returns are modest. If you run appliances in daylight, work from home, or add a battery to store solar for the evening, self-use climbs and so does the saving — because you avoid the much higher import rate.
Batteries add cost and payback
A 4 kWp system at £6,500
A 4 kWp system generates about 3,600 kWh a year. With 50% self-use at 27p, that's about £486 in bill savings, plus 1,800 kWh exported at 15p for £270 — roughly £756 a year. Against a £6,500 install, payback is around 8–9 years, after which it's largely profit across the panels' 25-year-plus life.
Common solar mistakes
- Overestimating self-use. If you export most of your generation, returns are far lower than the headline savings suggest.
- Ignoring roof orientation. North-facing or heavily shaded roofs generate much less; get a proper site assessment.
- Forgetting inverter replacement. Inverters often need replacing once in the system life, an extra £800–£1,500.
- Choosing the cheapest quote blind. Compare equipment quality and warranties, not just price — get several MCS-certified quotes.