Home Cost Australia

Solar Battery Payback Calculator

Model simple battery payback and 10-year savings using your installed cost, usable capacity, solar surplus, electricity tariffs and efficiency assumptions.

After any rebate you expect. e.g. 9000

Spare solar after daytime use.

Use after sunset.

Your estimate

Enter your values and select Calculate to see the estimate.

How payback is modelled

Each year the model charges the battery from your spare solar, delivers that stored energy to your overnight load, and values it against your tariffs:

  • Charge input = the lesser of your solar surplus and the battery's usable capacity ÷ round-trip efficiency.
  • Delivered energy = the lesser of your overnight load and charge input × efficiency.
  • Avoided import = delivered × import rate × 365 days.
  • Forgone export = charge input × feed-in rate × 365 days.
  • Net yearly saving = avoided import − forgone export + any VPP benefit.

Usable capacity shrinks each year by the degradation you enter, and savings accumulate until they reach your installed cost.

Why payback can be “never”
If your feed-in tariff is close to or higher than your import tariff, storing energy instead of exporting it can save little or nothing. The model reports this honestly rather than forcing a payback number.

What this does not include

Financing/interest, future tariff changes, maintenance and future rebate changes are excluded unless you build them into your inputs. Results are a model, not a quote or a savings guarantee.

How to improve the estimate

Use your real import and feed-in rates from your bill, a realistic overnight load, and the manufacturer's usable capacity and round-trip efficiency. Try a few scenarios rather than trusting one national payback claim.

How we calculated this

This estimate uses transparent inputs and a fixed formula. See our methodology for how ranges, sources and assumptions work.