How to use the battery calculator
Pick your state and battery
Set the usable capacity from your quote, and whether the battery has its own inverter or joins an existing hybrid.
Enter your quote
Replace the default price with the installed price after the federal discount.
Set the daily kWh stored
The smaller of your spare solar and your evening use, averaged across the year. See what size battery you need.
Check your rates
On a time-of-use plan, use your evening peak rate, since that is when the battery discharges.
Default battery prices
| Usable capacity | Battery only | With inverter |
|---|---|---|
| 10 kWh | $7,784 | $8,284 |
| 20 kWh | $14,972 | $15,772 |
| 30 kWh | $22,489 | $23,089 |
| 40 kWh | $29,911 | $31,111 |
| 50 kWh | $38,534 | $40,034 |
Ways to improve battery payback
- Use the evening peak. On a time-of-use plan the battery saves your peak rate, often well above the flat rate. See time of use tariffs.
- Join a VPP. Credits and the NSW incentive add income. See virtual power plants.
- Claim state help. WA households can get up to $1,300 or $3,800 off. See battery rebates.
- Size it right. A battery that empties every evening pays back faster than one that rarely does.
Backup has value too
The calculator only counts bill savings. If blackout backup matters to you, that is worth something the numbers do not show. See solar in a blackout.
Questions about battery payback
Each kWh of solar you store and use in the evening saves your usage rate, less round-trip losses, but gives up the feed-in tariff you would have earned. Multiply that gap by the kWh stored each year, add any VPP income, and divide the price by the result.
Less than its size on many days. It is limited by spare solar and by how much you use after dark. Smart meter data shows both. Across a year, a battery often averages well below a full cycle a day.
Usually because the gap between your evening rate and feed-in tariff is small, or the battery is bigger than you can fill. Try your time-of-use peak rate, a smaller battery, or add VPP credits.
Yes. The pre-filled price is after the federal Cheaper Home Batteries discount. Take off any state rebate, such as WA's, yourself.
Sources
Battery prices are from the Solar Choice Battery Price Index, an industry source. Discount rules are from the Clean Energy Regulator. Last checked October 2026. Prices include GST unless we say otherwise.