When is a home battery worth it?

A battery is worth considering when you want specific circuits on during an outage, or when your tariff pays very little for exports and a lot for evening power. It is a weak purchase when you are only trying to make a solar chart look larger.

Two jobs

Backup needs an inverter that can form a local grid and a list of circuits. Hours of runtime are stored energy divided by the load you leave on. A median 2025 residential battery in Berkeley Lab's data was 13.5 kWh. That is not several days of air conditioning.

Bill management means charging when power is cheap or solar is abundant and discharging when retail power is expensive. That case is stronger where exports are paid poorly, and weaker where exports are still credited near retail.

The price gap

Berkeley Lab reported that cash-purchase solar paired with storage had a median price about $2.10 per watt higher than stand-alone solar in 2025. Attachment of storage rose from 25 percent of residential installs in 2024 to 37 percent in 2025. Most 2025 installs still did not include a battery. "Everyone adds one" is false.

Our calculator ignores batteries on purpose. They do not increase the roof's annual production. See batteries for the equipment limits, including the difference between kilowatt-hours and kilowatts.