Free Solar Calculators That Actually Work
Get instant, accurate answers on panel tilt angle, system sizing, voltage, wire gauge, and installation cost. No signup, no email — just numbers. Built for UK homeowners and DIY installers.
Most popular calculators
- How Many Solar Panels Do I Need?Free UK calculator to estimate how many solar panels your home needs. Uses MCS-aligned irradiance, average British household consumption (2,700 kWh/yr), and 400 W panel specs.
- Solar Export Tariff (SEG) CalculatorCalculate your annual Smart Export Guarantee revenue. Free 2026 calculator with Octopus Outgoing 15p, E.ON Next Export 16.5p, EDF SEG 5.6p, and OVO Smart Export Plus rates.
- EV Charging Calculator (UK)Free EV charging calculator for UK drivers. Estimate kWh drawn, charge time on a 7 kW home wallbox, electricity cost at 2026 Ofgem cap rates, and the savings if you charge from solar PV.
- Off-Grid Solar System Calculator (UK)Free UK off-grid solar calculator. Sizes PV array (kWp), battery bank (kWh), and inverter (kW) from daily kWh load using PVGIS irradiance data and MCS-aligned design factors.
- Solar Investment Tax Credit Calculator (UK)Free commercial solar investment tax credit calculator for UK businesses. Estimate your Annual Investment Allowance (AIA), 50% First-Year Allowance, Smart Export Guarantee tariff, and net cost after every business incentive.
- SEG Net Export Savings Calculator (UK)Calculate your annual electricity bill savings under the UK Smart Export Guarantee (SEG). Compares Octopus Outgoing, E.ON Next Export, OVO, EDF and British Gas tariffs.
- Solar Panel Savings Calculator (UK)Free solar panel savings calculator for UK homes. Estimate 25-year lifetime savings using your annual generation, Ofgem tariff cap rate, SEG export tariff, self-consumption rate, and price escalation.
- Cost of Solar Panels Calculator (UK)Free UK solar panel cost calculator. Estimate installed cost from your monthly kWh, peak sun hours, £/W price, and the 0% VAT relief. 2026 MCS, Energy Saving Trust and Solar Energy UK data.
- EV Charging Cost Calculator (UK)UK EV charging cost calculator using April 2026 Ofgem cap rates and Octopus Intelligent Go off-peak tariffs. Per-session and annual running cost on a 7 kW wallbox plus solar PV offset.