Is a Home Battery Worth It? Costs, Savings and Backup Power

Batteries such as wall-mounted lithium systems have become a common add-on to rooftop solar. They store surplus midday power and release it in the evening, and they can power essential circuits during an outage. Whether they make financial sense depends on how your utility bills you.

What a battery costs

A typical residential battery with around 10–15 kWh of usable capacity costs roughly $10,000 to $16,000 installed, including the inverter or gateway and electrical work. Adding a second unit for whole-home backup can push the total well above $20,000.

Where batteries save money

• Low export credits: If your utility credits exported solar power at a fraction of the retail rate — as under California's net billing tariff — storing it for your own use is worth much more than exporting it.
• Time-of-use rates: When evening electricity costs two or three times as much as off-peak power, shifting usage with a battery saves money every day.
• Demand charges: Rare for homes, but common for small businesses.

A simple payback check

Suppose a 13.5 kWh battery shifts about 10 kWh per day from export (worth $0.05) to self-use (worth $0.30). That is $2.50 a day, or about $900 a year. At $13,000 net cost, simple payback is roughly 14 years. With full one-to-one net metering, the same battery saves almost nothing, because exported power already earns the full rate.

Backup power: the real value for many

If your area has frequent outages from storms, wildfire shutoffs or an unstable grid, the value of keeping the fridge, internet, medical devices and some lights running is hard to put in dollars. Unlike a generator, a battery is silent, needs no fuel and switches over automatically.

Incentives and programs

Some states and utilities offer battery rebates or pay homeowners to let the utility draw on their battery during peak demand (“virtual power plant” programs). These payments can shorten payback considerably. The federal residential clean energy credit for batteries ended for systems installed after 2025.

Battery lifespan

Warranties typically cover 10 years and guarantee around 70% of the original capacity at the end. Capacity fades slowly with each charge cycle, so a battery that cycles every day will age faster than one used mainly for backup.