Solar Battery Payback

Free Solar Battery Payback calculator with clear step-by-step results.

About Solar Battery Payback

A home battery earns the difference between the import price it avoids and the export tariff it gives up, not the full import price - a distinction that changes payback dramatically. Round trip efficiency reduces delivered energy, and dividing warranted cycles by annual cycling shows whether payback arrives before the warranty expires.

Formulas

Annual saving

Saving = usable capacity x round trip efficiency x cycles x (import price - export price)

Warranty life

Years = warranted cycles / cycles per year

Worked example

With the default values below, Solar Battery Payback returns Simple payback of 13.48. Change any input above and every figure here is recalculated in your browser.

Inputs used

Installed battery costminimum 0 $: 9,000 $
Usable capacityminimum 0.5 kWh: 10 kWh
Full cycles per yearaccepts 1–400: 300
Round trip efficiencyaccepts 50–100 %: 89 %
Grid import priceminimum 0 $/kWh: 0.32 $/kWh
Export tariff forgoneminimum 0 $/kWh: 0.07 $/kWh
Warranted cycle lifeminimum 100 cycles: 6,000 cycles

Results

Simple payback: 13.48 years
Annual bill saving: $667.50
Years of warranted life at this cycling: 20.0 years
Net benefit over the warranted life: $4,350.00

Step by step

1Values used
2Annual saving
3Warranty life
4Simple payback= 13.48 years
5Annual bill saving= $667.50
6Years of warranted life at this cycling= 20.0 years
7Net benefit over the warranted life= $4,350.00

Assumptions and limits

The result is derived only from the 7 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation or tax into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why subtract the export tariff?

Energy stored in the battery is energy you did not export. The saving is only the spread between what importing costs and what exporting would have paid.

Does a battery pay back on solar alone?

Often marginally. Payback improves sharply with time-of-use tariffs where you can arbitrage cheap overnight import against expensive evening peaks.