How a battery actually lowers your bill

Here's the part most sites get wrong: on a standard flat rate, a battery by itself saves almost nothing. The savings come from switching to a time-of-use rate — if your utility offers one. Power is cheap overnight and expensive during a peak window; your battery charges when it's cheap and runs your home during the pricey window, so you buy very little at the high rate. Add solar and you store your own daytime power to use at night.

Here in South Carolina, that switch is moving from Dominion's standard plan (Rate 8) to its time-of-use plan (Rate 7) — and a battery is what makes it pay off. Whether your own utility has an equivalent depends on where you live, which is exactly what the analyzer sorts out for you.

In plain English: charge when it's cheap, use it when it's expensive.

More: Rate 7 vs Rate 8 — which is actually cheaper, and the demand charge that can bite you.