Free Tools
Solar & Off-Grid Power Tools
Free calculators to help you size your system before you buy. No guesswork, no signup.
Off-Grid System Builder
Design a complete system in four steps: battery bank, solar array, charge controller and inverter, matched to your use case.
Open tool →Solar & Battery Sizing Calculator
Work out how many solar panels and what size battery bank you need for your daily energy use.
Open tool →Power Station Runtime Calculator
Work out how long a power station will run your devices, or what capacity you need to buy.
Open tool →Inverter Size Calculator
Size an inverter for your appliances, accounting for running load and motor start-up surges.
Open tool →MPPT Charge Controller Calculator
Match an MPPT controller to your solar array and battery bank, with cold weather voltage headroom.
Open tool →Battery Charge Time Calculator
Estimate how long a battery takes to charge from mains, solar or an alternator.
Open tool →Cable Size Calculator
Find the right cable size for a 12V, 24V or 48V run based on current, length and voltage drop.
Open tool →Solar Payback Calculator
See how quickly a UK solar system pays for itself, plus annual savings and 25 year net benefit.
Open tool →EV Charging Cost Calculator
Compare the cost of charging an EV at home, off-peak and at public chargers against petrol.
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