Solar Panel Calculator
Estimate how much electricity a solar system generates and saves.
Estimated annual value
£882.00
- Annual generation
- 3,600 kWh
- Monthly average
- 300 kWh
Estimate only — actual output depends on roof orientation, shading and location.
v1.0 · Reviewed September 2026
How this is worked out
Annual generation is the system size × the annual generation per kW you enter, and the value is that generation × the price per kWh.
Worked example
- 4 kW system
- 900 kWh per kW a year
- 24.5p per kWh
3,600 kWh × 24.5p
£882.00 a year from 3,600 kWh
Assumptions and limits
- Uses the yield per kW you enter. Real UK figures depend heavily on location, roof pitch, orientation and shading, and a north-facing or shaded roof produces far less than a south-facing one.
- Values every generated unit at the full electricity price, which only holds if you use it all yourself. Exported units are paid at the lower Smart Export Guarantee rate, so a home that is empty during the day earns less than this.
- Ignores panel degradation, inverter replacement and maintenance.