Solar savings calculator — get an estimate in under a minute

System sizing

The system is sized to match your annual electricity usage (estimated from your bill at 27p/kWh average). UK residential systems typically range 3-7 kWp. Larger homes with EVs or heat pumps justify 5-7 kWp.

Annual generation

Generation = kWp × peak sun hours × aspect derate. North East England averages 1,050 peak sun hours per year for a south-facing roof. East/west-facing roofs derate to ~85%; north-facing to ~60%.

Self-consumption

Without battery: 30-40% of generation is used directly (lights, fridge, washing). 60-70% exports to grid at the SEG rate. With a 10 kWh battery: 70-80% self-consumed, 20-30% exported.

Savings calculation

Bill savings = self-consumed kWh × 27p (the price you would have paid). SEG income = exported kWh × 15p (current Octopus Outgoing Fixed rate). Total annual benefit = savings + SEG.

Install cost

Estimated from system size + battery option using current AMP Renewables price ranges. Includes panels, inverter, scaffolding, MCS cert, DNO notification. Battery adds £4,800 (5 kWh) to £7,500 (10 kWh).

Payback

Simple payback = install cost ÷ total annual benefit. Doesn't account for electricity price inflation (which makes payback faster), panel degradation (~0.5%/year, makes it slightly slower), or maintenance (negligible for residential).

Want a property-specific quote? Our free survey runs the full BS EN model + 3D roof shading analysis. The estimate is typically within 5-10% of the calculator output. Book a free survey.