See whether a home battery pays for itself just by shifting when you draw from the grid — charge cheap, use expensive, every day.
A meaningful rate spread makes this attractive even without solar — pairing the battery with solar (self-consumption + arbitrage) usually shortens payback further.
Further reading: Solar Battery Storage 101: Sizing, Cost, and Whether It's Worth It
This models the battery purely as a bill-shifting device — charging on cheap off-peak power and discharging during expensive peak hours — separate from any solar self-consumption benefit. If you're also pairing the battery with solar, actual combined payback is typically faster than either benefit calculated alone, since the two savings streams stack.
It's most compelling where utilities have a wide peak/off-peak spread — markets like California, parts of Australia, and UK Economy 7/10 or EV-specific tariffs. Where the spread is narrow, battery ROI usually depends more on solar self-consumption or backup value than arbitrage.
The Solar ROI Calculator values solar production offsetting your bill. This tool isolates the separate, additional value a battery brings from shifting when you draw power — useful for deciding whether adding a battery to an existing solar system, or even without solar, is worth it.