Home battery payback calculator

Estimate the money a home battery could save in its first year. Start with the electricity it could supply over a year, not just the energy it can hold at once. Use battery records or an installer report that matches your home and planned use.

Collect your spare solar, household demand, battery delivery and full-system efficiency for the same year. Spare solar means generation left after direct home use. Battery delivery means energy reaching the home after battery and inverter losses. The form checks that the entered energy amounts fit together.

Add the installed quote, confirmed discounts, extra maintenance and any net VPP income. A VPP is a group of batteries controlled by a provider. Enter its income after fees, or zero if none applies.

Capacity and yearly delivery use the same kWh unit but mean different things. Capacity is the energy the battery can hold at one time. Yearly delivery adds up energy supplied across many uses. Where the optional scheme asks for nominal or usable capacity, take that exact figure from the final product documents. Do not substitute annual delivery or a different battery size.

Enter measured or installer-modelled annual battery delivery. Charging energy = delivered energy ÷ full-system round-trip efficiency. Check charging against available spare solar and delivery against household demand. Annual net benefit = avoided import cost minus foregone export on charging energy plus confirmed net VPP income minus maintenance. Simple payback = net installed quote ÷ positive annual benefit.

Use a percentage as a fraction once: for example, 50% means 50 ÷ 100 = 0.5. Use 0.5 in the energy formula; do not divide it by 100 again.

Read the annual net benefit before the payback figure. Solar used to charge the battery gives up export income, so avoiding a grid purchase is not the whole saving. A zero or negative benefit has no finite payback.

These illustrative inputs are separate from your saved answers. Prices, use and performance are held constant for this worked scenario; they are not personal defaults.

Use annual battery delivery from monitoring records or an installer assessment, and your quoted installation price and confirmed discounts for simple payback.

The estimate keeps the entered prices and yearly energy amounts constant. It does not predict future tariffs, battery wear, finance costs or replacement costs. Simple payback shows how long the entered yearly benefit would take to cover the entered net price.

Every optional eligibility answer needs evidence. No or Not sure stops that optional estimate. WA and NSW one-off incentives are separate from recurring net VPP income. Already included offers are not deducted twice. Later payments do not reduce the upfront payback cost. NSW checks use the rule effective 12 October 2026. Final approval remains with the installer, provider and regulator.

This Australian tool uses your actual import price, solar export price and written quote. Use prices for the hours the battery would supply electricity. A general electricity average may not match those hours or your contract.

Certificate and regional incentive checks use the dated sources linked below. An estimated certificate count is not a promised discount. For payback, enter the actual discount in your quote and count each payment once. Check the certification date, final battery setup and provider terms.

Ask an accredited installer to confirm battery compatibility, usable capacity, safe installation and rebate eligibility. Bring the written quote, tariff, battery documents and annual energy report so they can check the same setup used here.

Ask the VPP provider to explain fees, control of your battery and any one-off offer in writing. The calculator does not approve an application or confirm that a battery will meet your needs.