Solar Payback Calculator
Drag the sliders to estimate your annual generation, yearly benefit and how long a solar system would take to pay for itself.
Default follows the DESNZ 2025/26 mean for this size band. Costs fall per kW above 4kW.
Est. annual generation
4,360 kWh
Annual benefit
£835
£574 avoided imports + £262 export on Outgoing Octopus
Payback time
8.7 yrs
Yield from PVGIS; shading is not modelled and can cost far more than the shaded fraction.
Enter a postcode for your grid region's electricity and export rates.
Assumptions
- Generation
- PVGIS, 35° pitch, 14% system losses, by region and orientation (EC JRC PVGIS)
- Install cost
- DESNZ 2025/26 mean domestic £/kW by size band, VAT included, no battery (DESNZ Solar PV cost data)
- Import price
- 26.32p/kWh, Ofgem price cap, 1 October to 31 December 2026; enter a postcode above the calculator for your region's Octopus rates (Ofgem)
- Export price
- 12p/kWh, Outgoing Octopus; enter a postcode above the calculator for your region's Octopus rates (Octopus)
Rates checked 20 September 2026. Check them again before you commit to anything.
Get exact quotes
How it works
Generation is PVGIS's figure for your region, scaled by orientation and pitch. The share you use at home is valued at your import price; the rest at your export rate. Payback is install cost divided by the yearly benefit. Rates checked 20 September 2026.