How home battery backup works with your house and solar panels
Last edited
Author
Andrew Blok
Electrification and Solar Writer and Editor
Editor
Ryan Barnett
SVP, Policy & New Market Development
Maybe you already have home solar panels and still lost power in the last storm. Or you are weighing solar and wondering whether a battery belongs in the plan.
A home battery backup system stores electricity from your solar panels or the grid, then powers a chosen set of circuits in your home when the grid goes down. An automatic switch separates your house from the utility so the battery's power goes only to your home. With solar, the panels can recharge it on sunny days.
How home battery backup works
Your battery works in the background, charging when power is plentiful and giving it back when you need it.
On a normal sunny day, your panels power your home first, and extra solar charges the battery. In the evening, the battery covers part of what your house uses, and the grid fills in the rest. Depending on your utility's rules, extra solar may also flow to the grid, as our guide to how solar power and the grid work together explains.
When the grid goes down, here is the annoying reality: solar panels without a battery usually shut off in a power outage. That way power doesn’t flow onto lines that utility crews may be working on. With a battery, the switch isolates your home first and the battery keeps your backed-up circuits running. If your system is set up for it, solar can top the battery off during the day.
Batteries do not need solar to work, and Palmetto Energy Backup is available with solar panels or without them.
What a battery can run
A battery powers only the circuits wired to it, and your installer helps you choose them. Common picks are the refrigerator, lights, and internet router. One battery will not run an entire home, since central air conditioning, an electric dryer, or an electric oven can use a lot of power quickly. Whole home battery backup will require more than one battery (and more money).
Runtime depends on how much energy the battery holds and how much you draw from it. Capacity is measured in kilowatt-hours (kWh), the energy a 1,000-watt appliance uses in an hour. Berkeley Lab's 2026 data update found the median home battery installed with solar in 2025 held 13.5 kWh. A refrigerator and a few lights can stretch that amount of electricity much further than an oven does.
| Setup | Sunny weather | Cloudy weather |
|---|---|---|
| Small battery (5 kWh) + heat pump | 9+ hours | 7 hours |
| Small battery (5 kWh), no heat pump | 7+ days | 18 hours |
| Large battery (10+ kWh), no heat pump | 7+ days | 49 hours |
| Large battery (10+ kWh) + heat pump | 7+ days | 19 hours |
Estimated runtimes based on backing up a refrigerator, WiFi, phone chargers, television, microwave, lighting, and two laptops. kWh means kilowatt-hour, the standard unit for measuring an amount of electricity.
Benefits of home battery backups
The biggest benefit is power for the things you care about most when the grid goes down.
How much that matters depends on how often your power goes out. The U.S. Energy Information Administration measures the total time the average customer goes without power in a year. EIA reported that the average U.S. customer lost power for about 11 hours in 2024, nearly twice the prior decade's yearly average. Hurricanes drove about 80% of those hours. Outages not tied to major events routinely average about two hours a year.
Averages hide a lot. South Carolina customers averaged nearly 53 hours without power in 2024, the year of Hurricane Helene. If your area rarely loses power, a battery's backup value may be smaller. If storms hit your area often, you might value it more.
A battery can also help with your bills, depending on your utility. Solar battery storage lets you use solar energy after sunset instead of sending it all to the grid. That can help if your rates change by time of day, as covered in our guide to peak and off-peak electricity hours, or if your utility pays little for the solar you send back. If your utility credits that solar at the full retail rate, a battery adds less savings. Ask your installer for an estimate with and without a battery, based on your utility's rates.
Cost of home batteries
Solar backup battery cost is heavily dependent on the storage capacity you choose, and the following factors can influence your ultimate cost.
- Hardware: Adding additional batteries will increase your cost.
- Labor: The local cost of labor can be a significant factor.
- Permitting: Permitting costs are a real, though smaller, difference from place to place.
Battery leasing with Palmetto Energy Backup
A lease lets you add a battery without paying for it upfront. Instead, you make predictable monthly payments for a battery you lease from the company that owns it.
Palmetto’s Energy Backup is a battery lease with a 12-year term, a predictable monthly payment, and $0 upfront. Maintenance and common repairs are covered, too.
To compare, add up the monthly payments over the term and weigh them against a purchase price. Also ask what happens when the term ends.
Read more: How battery leasing works
Once you know how much of your home you’d like to backup up and whether buying or leasing suits you, see what fits your home. You can explore storage options with Palmetto, with or without solar panels, or reach out for a quote.
See how much you can save by going solar with Palmetto
Frequently asked questions
Can I add a battery to solar panels I already have?
Often, yes, depending on your existing equipment. An installer will check your inverter, which converts your panels' power for home use, before quoting.
How is a home battery different from a generator?
A generator burns fuel to generate electricity, while a battery stores electricity for later use. A generator is limited only by the supply of fuel. A battery is limited by its storage capacity between rechargings. Connected to solar panels, a battery can recharge each day. Generators also have higher maintenance requirements and the risk of toxic fumes. Read more.
How long does a home battery last?
It varies by battery and how you use it. Warranties usually state a term in years (often 10 years) and the capacity the battery should retain, so compare both.
During an outage, it depends on how much of your home you decide to back up, how heavily you use those devices, and whether you have solar panels to recharge your battery.
Disclaimer: This content is for educational purposes only. Palmetto does not provide tax, legal, or accounting advice. Please consult your own tax, legal, and accounting advisors.
