UK Energy Calculators

Real calculations from your property's details.

Four tools that size the kit you're considering against your home — its EPC band, floor area, roof and usage, as you enter them — with every assumption shown in the maths. Not a black-box national average.

Sizing tool

Solar panel sizing

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Roof orientation, area, and postcode → recommended kWp, expected annual generation, Smart Export Guarantee income estimate, payback period.

Inputs: postcode · roof orientation · roof area · annual electricity usage

Sizing tool

Heat pump sizing

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Property age, floor area, and EPC band → recommended kW capacity, installed cost range, Boiler Upgrade Scheme grant offset, net cost after grant.

Inputs: property type · age band · floor area · EPC band (you select)

Sizing tool

Battery storage sizing

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Daily kWh use, current tariff (Octopus Agile / Cosy / Tracker / fixed) → recommended battery kWh, expected annual arbitrage savings, payback period.

Inputs: daily electricity use · current tariff · optional solar PV size

Eligibility check

Grant eligibility wizard

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Postcode + EPC band + property type + Council Tax band → every UK energy grant you might qualify for (BUS, Warm Homes Plan, GBIS, regional schemes), with indicative funding values.

Inputs: postcode · EPC band (you select) · property type · heating fuel · Council Tax band

How these calculators work

Plenty of energy calculators hide their working — you get a single number with no sense of what drove it. These ask you for your property's actual details (EPC band, floor area, roof, usage) and show every assumption in the maths, so the recommendation is calibrated to what you tell them rather than a national mean.

They don't look up your EPC band for you. If you don't know it, you can check it free on the gov.uk EPC register, or use the grant checker on our homepage, which reads your live band from the MHCLG register. Enter it here and the sizing is tuned to your home.