Free Australian calculator
Solar and battery calculator for Australian homes
Enter a few figures from one electricity bill. See what solar alone, a 10 kWh battery and a 20 kWh battery could save each year, what each extra step adds, and the most each is worth paying for your payback target. No sign-up, and nothing you enter is stored.
- 01Your home
- 02Your usage
- 03Your priorities
- 04Your options
What the calculator shows
- Yearly bill saving for each option, compared with keeping your current setup and plan.
- The extra value of each step, so a larger battery is compared with a smaller one, not only with no battery.
- Worth paying up to: the total estimated saving over your chosen payback period.
- The best-value size for your home: every solar size from 5 to 13.2 kW, with and without a battery, ranked at typical installed prices for your city.
- An average summer and winter day, hour by hour: how much of your power would come from your own solar, the battery and the grid.
- Your roof and your plans: which way the panels face, shade, and a planned electric car.
- Checks still needed, such as switchboard work, network approval and backup design.
Want the detail? Read how the calculations work, or see a city-by-city battery size comparison.
Questions about the calculator
What do I need from my bill?
The electricity you used (or imported, if you have solar) in kWh, the number of days in the billing period and its end date, and your usage and feed-in rates in cents per kWh. If you have solar, also the kWh you exported. The daily supply charge is optional.
Does it work in my state?
Yes. It uses a regional solar profile for each state and territory, from Perth to Hobart and Darwin. It handles flat plans, time-of-use plans with a 3pm–9pm peak and an optional cheap midday rate, and feed-in that pays more from 3pm to 9pm, as with Western Australia’s buyback scheme.
How accurate is it?
It’s a preliminary estimate. One bill can’t show exactly when you use power, so results are calculated for evening-heavy, mixed and daytime use and shown as a range. Solar output uses regional averages for a north-facing, unshaded roof, not your roof. An installer site check is still needed.
Is my information stored?
No. The calculator runs in your browser and what you type is not uploaded. If you choose “Save or share link”, your answers are put in the part of the web address after the #, which browsers don’t send to us; anyone you give the link to can see them.
Does it include rebates?
Typical prices already have the federal battery discount taken off. State battery incentives are included only if you choose your state’s scheme, and VPP payments aren’t modelled. Our guides explain the current programs.