Home energy estimate

Home battery payback calculator

Estimate whether storing lower priced electricity for use later could offset a home battery’s installed cost. Enter your actual quote and tariff rates for a more relevant estimate.

Your battery and tariff

All values are editable. Example values are provided to demonstrate the calculation.

Installed battery cost

Use the full quoted price, including installation.

Usable battery capacity

kWh

Energy available for use, not the battery’s headline nominal capacity.

Off peak electricity rate

p/kWh

Peak rate avoided

p/kWh

Rate you would otherwise pay when using the stored energy.

Round trip efficiency

Accounts for energy lost while charging and discharging.

Equivalent full cycles each year

cycles

One equivalent full cycle uses the battery’s full usable capacity once.

Evaluation period

years

Your estimate

Potential tariff savings

Based on shifting energy from your off peak rate to the peak rate entered.

Estimated annual bill saving£0Using the inputs shown

Simple paybackNot reached

Net over selected period£0

Effective stored energy cost0p/kWh

Rate gap after losses0p/kWh

How it is estimated
Annual saving = usable capacity × equivalent full cycles × (peak rate − off peak rate ÷ efficiency fraction). Payback = installed cost ÷ annual saving.

This is a tariff shifting estimate, not a guarantee. It assumes the usable battery capacity is discharged on each cycle. It excludes solar self use, export income, degradation, financing, maintenance and future tariff changes. Battery storage also loses some energy when it is cycled. See Energy Saving Trust guidance. The default £4,600 is an illustrative 5 kWh system figure from that guidance, not a quote.