Solar savings calculator
Estimate how much electricity a solar PV system could generate and what it could save on your bills.
Your estimate
Savings in year one
£696
- Solar generation per year
- 4,092 kWh
- Used in the home
- 1,432 kWh
- Exported to the grid
- 2,660 kWh
- Simple payback
- 9.4 years
- Net savings over 25 years
- £13,901
Estimates for planning only — not a quote, survey or financial advice.
Sources for the pre-filled values — United Kingdom
- European Commission JRC — PVGIS 5.3, grid-connected PV (optimal angles, 14% system loss) · Radiation data 2005–2023 (SARAH3; ERA5 for the US) · accessed 2026-11-06 · Reference sites: Kansas City (US), London (UK), Paris (FR), Frankfurt (DE), Madrid (ES), Rome (IT).
- Ofgem — Energy price cap unit rates (Great Britain average, Direct Debit) · 1 October – 31 December 2026 · accessed 2026-11-06 · Unit rates only; daily standing charges are not included.
- Ofgem — Typical domestic consumption values (medium), from 1 July 2026 · 2026 TDCV · accessed 2026-11-06
How this is calculated
Formula
- Generation = system size × annual yield per kWp
- Used at home = generation × self-use share (capped at your consumption)
- Year-one savings = used at home × electricity price + exported × export payment
- Later years: savings × (1 − 0.5% panel degradation per year) × (1 + price change)
- Payback = years until cumulative savings cover the installed cost
Assumptions
- Yield depends on location, roof pitch, orientation and shading. The pre-filled value comes from the EU's free PVGIS tool for one reference city per country; enter your own address in PVGIS for a site-specific figure.
- Without a battery, homes often use around a third of their solar output; batteries and daytime use raise this share.
- Maintenance, inverter replacement, financing and incentives are not included.
- Not financial advice.