What is this?
A quick planning tool for solar & battery
howmuch.solar is a free calculator that helps you work out how many solar panels and what size battery your home actually needs — and roughly what you should expect to pay, and how long it should take to pay for itself.
It's built for anyone starting to shop for solar or a battery, whether you're going solar for the first time or you already have panels and are just weighing up a battery. It's a starting point for your own research and installer quotes, not a substitute for either.
How it works
- Tell us about your roof. Your nearest city and how much shade you get set how much usable sun you're working with.
- Tell us about your electricity use. Either enter your annual usage directly, or answer a few quick questions about your home and we'll estimate it for you.
- Tell us what you pay for power. Enter your rates from a bill, or a rough monthly amount if you don't have one handy.
- Get your numbers. The calculator works out the solar and battery size with the fastest payback for your home, then shows your savings, total investment, and a shopping list to take to installers.
- Adjust your payback period. Once you've seen your results, slide the payback period to see what size system and what prices would get you there — the prices become your target to negotiate toward with installers.
Every slider stays live, so you can keep adjusting sizes and prices to see how your payback period changes — see the "See calculations" and "See assumptions" buttons on the results for exactly how the numbers are built.