Home Battery Payback Calculator
Work out whether a home battery pays for itself by comparing stored energy value against the feed-in tariff forgone, including round-trip losses.
Illustrative default — peak tariffs vary by retailer, state and plan.
What you'd otherwise earn or pay — e.g. off-peak tariff or feed-in rate, both of which vary.
Rebate availability and amount vary by state and scheme.
Your results
Actual prices, usage, efficiency and savings vary by provider, equipment, location and behaviour.
Calculation breakdown
- Value per cycle
- 10 kWh × 90% × (0.35 − 0.08) = $2.43
- Annual saving
- $2.43 × 1 cycles/day × 365 = $886.95
- Payback period
- $9,000.00 ÷ $886.95/yr = 10.1 years
Assumptions
- Tariffs, feed-in rates and rebates vary by state, retailer, plan and time — all values here are illustrative user inputs, not official figures.
- Battery degradation is applied evenly across the warranty period; actual degradation curves vary by chemistry and usage.
- Value per cycle assumes the full usable capacity is cycled at the stated efficiency each cycle.
- Excludes financing costs, maintenance and any change in tariffs over the projection period.
How this calculator works
Enter battery capacity, usable depth of discharge, round-trip efficiency, daily cycling, your electricity rate and feed-in tariff. The calculator values each stored kilowatt-hour at the difference between the retail rate avoided and the export credit forgone, then estimates annual savings and payback years.
Frequently asked questions
Why subtract the feed-in tariff?
Energy stored in the battery would otherwise have been exported and earned a credit, so only the difference between the retail rate and the feed-in tariff is a genuine saving.
What is round-trip efficiency?
The share of energy put into the battery that can be drawn back out, typically around 90% for modern lithium systems.
Does backup power add value?
It can, but blackout protection is a reliability benefit rather than a cash saving and is not included in the payback figure.
Actual prices, usage, efficiency and savings vary by provider, equipment, location and behaviour.
Results are estimates only and are not financial, tax, legal or credit advice.