How big an inverter, battery and solar setup do you need?
List what you want to keep running, say how long your power goes off, and pick your town. The calculator sizes the inverter, battery and solar panels, using 25 years of NASA sunshine data for where you live.
- Works for any town in the world
- Free, no sign-up
- Every formula shown openly
What the numbers mean
The inverter turns battery power into the kind your sockets supply. It has to carry everything you run at once, plus the brief surge when a fridge, pump or air conditioner starts.
The battery stores the energy you use while the grid is off. Its size depends on how much you run and for how long, and on the battery type: lead-acid batteries should only be drained about halfway, so you need more of them.
Solar panels refill the battery, or run the house outright. How many you need depends on your sunshine, which is why the calculator plans for the month with least sun by default.
Every formula and assumption is on How we calculate. Use the result to compare installer quotes and spot a system that is too small, or one that is padded.
New to this? Start with kVA vs kW, lithium vs lead-acid batteries and questions to ask an installer, or see all guides.
Sunshine and system sizes by city
- AustraliaSydneyMelbourneBrisbanePerth
- IndiaMumbaiDelhiBengaluruHyderabad
- NigeriaLagosKanoIbadanAbuja
- PakistanLahoreKarachiPeshawarFaisalabad
- PhilippinesQuezon CityDavaoManilaZamboanga
- South AfricaJohannesburgCape TownDurbanPretoria
- United KingdomLondonBirminghamGlasgowManchester
- United StatesNew York CityLos AngelesChicagoHouston