See the real solar & home-energy numbers — every assumption editable.

Payback, batteries, heat pumps, EV charging and tariffs with formulas printed in plain numbers. Not an installer lead form.

Toolkit

Nine calculators

Live results. Region defaults you can override.

Estimate simple payback and 25-year net gain from a rooftop PV system with transparent assumptions.

Size a PV array from annual consumption, target offset, and local specific yield.

Work out whether a home battery pays back by capturing more of your own solar.

Compare annual running costs using SCOP, boiler efficiency, and fuel prices.

Calculate home EV charging cost with day/night tariffs and compare to petrol.

Build a list of household appliances and see annual electricity cost by device.

Estimate payback for loft, cavity, draught-proofing and glazing with multiplicative savings.

Split usage across peak, off-peak and night bands and rank up to three tariffs.

Convert freely between kilowatt-hours, cost and CO₂ using editable grid intensity.

Guides

How the numbers work — and where installer quotes diverge.

Need a correction or want to advertise?

The contact form works — messages go to the site operator.