Solar calculators
Independent, conservative estimates for UK homeowners. Model your system size, savings, payback and battery ROI in under a minute.
Calculator 1
Solar savings & payback
Enter your bill and system size — we'll estimate annual savings, export income and payback in years.
Total annual benefit: £770 · Assumes 35% self-consumption without a battery and 950 kWh/kWp South East yield.
See your personalised recommendations
Share a few details and we'll show tailored next steps — or skip to see the generic recommendations.
We'll only pass your details to 1 vetted solar firm who's the best match — never multiple companies.
Calculator 2
What size solar system do I need?
Size the array to your yearly electricity use and roof space.
Expected generation: 3,600 kWh/year · Sized to the smaller of roof capacity or your usage target.
See your personalised recommendations
Share a few details and we'll show tailored next steps — or skip to see the generic recommendations.
We'll only pass your details to 1 vetted solar firm who's the best match — never multiple companies.
Calculator 3
Battery storage ROI
See the extra savings a battery unlocks by storing daytime surplus for evening use.
Assumes ~300 useful cycles a year and displaces grid import at the difference between import and SEG export price.
See your personalised recommendations
Share a few details and we'll show tailored next steps — or skip to see the generic recommendations.
We'll only pass your details to 1 vetted solar firm who's the best match — never multiple companies.
Calculator 4
EV home charging cost
Compare charging on solar vs the grid — annual fuel savings on your commute.
Petrol comparison uses 45 mpg @ £1.45/L. Solar-charged miles are costed at the SEG export price you'd have received instead.
See your personalised recommendations
Share a few details and we'll show tailored next steps — or skip to see the generic recommendations.
We'll only pass your details to 1 vetted solar firm who's the best match — never multiple companies.
Get the real number
Turn these estimates into a firm quote
A vetted MCS-accredited installer in your area will confirm generation and price after a free roof survey.
FAQ
How the calculators work
How accurate are these solar calculators?
They use conservative South East assumptions — 950 kWh per kWp per year, a 30p/kWh import price and a 15p/kWh SEG export rate. Your quote may vary after a roof survey.
What size solar system do I need?
Size to cover 80–110% of yearly consumption. A 3-bed South East home using ~3,600 kWh fits a 4 kWp array on a south-facing roof.
Do the calculators include a battery?
The battery ROI calculator is separate. It estimates extra self-consumption savings from storing daytime surplus for evening use.
Why is my payback longer than adverts suggest?
Ads often quote 100% self-use and best-case yields. We use 35% self-consumption without a battery and real South East yields — more honest, less flattering.