Time-of-Use Savings With a Home Battery

Time-of-use, or TOU, pricing charges you more for electricity when the grid is busiest and less when it is quiet. EnergySage explains that a home battery lets you buy low and use high by storing off-peak energy for use during expensive peak hours. This guide walks through how that saving actually works and where the numbers come from.

How time-of-use rates work

A TOU rate ties the price of electricity to the clock. EnergySage explains that under TOU rate plans your utility charges more during peak hours when demand is highest, and less during off-peak hours when demand drops.

The result is a bill that depends on when you use power, not just how much. Households that run heavy loads in the evening pay a premium under TOU, while households that shift usage to off-peak windows pay less for the same kilowatt-hours.

When peak hours hit

Peak pricing lands at the worst time for most families. EnergySage puts peak hours on weekdays between 4 and 9 pm, when residents return home, use appliances, run air conditioning, and cook dinner.

The cost difference across those windows is large. EnergySage states that rates during peak hours can be two or three times higher than off-peak rates, which turns the evening block into the most expensive electricity of the day.

How a battery captures the spread

A battery turns the price difference into a saving by shifting when you draw from the grid. EnergySage states that a home battery lets you store cheap off-peak electricity and use it during expensive peak hours, buying low and using high.

It calls this one of the most effective ways to manage TOU costs, with the added benefit of providing backup power during outages. A battery paired with solar can also store midday solar output for the evening peak, which layers a second source of cheap energy on top of off-peak grid power.

What determines your actual saving

The size of the saving depends on your local rate spread and your battery capacity. A wider gap between peak and off-peak prices makes each stored kilowatt-hour worth more, so households in areas with steep TOU differentials benefit most.

Your usable capacity sets the ceiling. A battery can only shave peak charges up to the energy it holds, so a system sized to cover your evening load captures more of the spread than a smaller one. Because peak windows and rate multiples vary by utility, EnergySage recommends confirming your own schedule with your provider before estimating savings.