Free Tool

Solar Savings Calculator

Estimate what rooftop solar could generate, save and pay back for your home. Change any assumption — the results update live.

System size (kWp)

Typical domestic system: around 4.5 kWp.

Expected yield (kWh per kWp per year)

Assumption — your installer gives a site-specific estimate for your roof.

Your annual electricity usage (kWh)

Share of solar you use at home (%)

Assumption — higher if you are home in the daytime or have a battery.

Electricity import price (p/kWh)

Oct–Dec 2026 price cap electricity rate.

Export (SEG) price (p/kWh)

Enter your Smart Export Guarantee rate — rates vary widely by supplier. Leave blank to skip export income.

Estimated annual benefit

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How it works: annual generation = system size × yield. Electricity you use at home saves you the import price; surplus you export earns the SEG price. System cost is estimated at £1,650–£1,780 per kWp (MCS data) — a typical 4.5 kWp system is around £7,600 (Energy Saving Trust). Simple payback divides the mid-point cost by the annual benefit and ignores price changes, panel degradation and inverter replacement. Treat all results as estimates and get itemised quotes from MCS-certified installers.