Estimate your savings, payback period, system size and more — using real UK sun hours, Ofgem electricity rates and Smart Export Guarantee tariffs. No signup, no email wall.
See your annual savings, payback period and 25-year profit based on your region and roof.
Calculate savings → LivePanel count by your usage and UK region sun hours.
Calculate panels → LiveInstalled cost by system size, with 0% VAT applied.
Calculate cost → LiveReturn on investment over 25 years, with rate inflation.
Calculate ROI → LiveIs a home battery worth it with your tariff?
Calculate battery ROI → Coming soonIncome from exporting surplus to the grid.
In progress NewCharge your EV with solar — savings vs petrol & grid, % coverage, panels needed.
Calculate EV savings →Real costs, savings, payback periods and who should skip — based on MCS, Ofgem & EST data.
Read guide → GuideEvery UK supplier's SEG rate compared. How much you can earn, eligibility, how to switch.
Read guide → GuideFull price breakdown by system size, what drives the price, 0% VAT impact, how to get cheaper.
Read guide → GuidePanel count by house size, usage, roof space and region — with the exact formula.
Read guide → NewLegal from 27 August. £400 kits, no electrician, save £70-110/year. Who it's for, safety rules, vs rooftop.
Read guide →SolarWatt UK is a free, independent reference tool. Every calculator uses public UK data — NREL / NASA sun hours, Ofgem tariff caps, and published Smart Export Guarantee rates.
We may earn a commission when you request installer quotes through our links. This never changes the numbers we show you. See our methodology page for the formulas behind each tool.