Solar

Home Battery Payback Calculator

A home battery saves money by storing cheap (or solar) electricity and using it when power is expensive. This calculator estimates your daily saving and how many years until the battery pays for itself.

Your details

Results

Estimated daily saving

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Estimated annual saving

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Payback period

Years until the battery pays for itself.

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Last updated June 30, 2026. Results update automatically as you type.

How it works

Usable energy per day = capacity × (round-trip efficiency ÷ 100). Daily saving = usable energy × (peak rate − off-peak rate). Annual saving = daily saving × 365. Payback = battery cost ÷ annual saving. This assumes one full cycle per day; if you cycle less often, real payback is longer.

Frequently asked questions

Is a home battery worth it?

It depends heavily on the gap between your peak and off-peak rates (or how much surplus solar you have). A bigger gap means faster payback. Many batteries pay back in 7–12 years.

What is round-trip efficiency?

The share of energy you get back after storing it. A 90% efficient battery returns 9 kWh for every 10 kWh you put in; the rest is lost as heat.

What if I charge from solar?

Set the off-peak/charging cost to $0 (or near it). Your saving then equals the full peak rate you avoid, which shortens payback significantly.

These calculators provide general estimates for educational purposes only and are not financial advice. Real-world results depend on factors not captured here. Verify figures independently before making any purchase or financial decision.