The lights flicker once. Then the TV goes black, the Wi-Fi cuts out, and the refrigerator stops humming. Now, you’re left wondering just how long this outage will go on. Will it last 20 minutes or all night?
It’s a situation California homeowners are all too familiar with. Planned Public Safety Power Shutoffs (PSPS), wildfires, severe weather, and grid issues have made backup power a bigger priority than ever.
Solar panels are a great way to lower your energy bills, but a standard grid-tied system won’t keep powering your home during an outage on its own. To enjoy uninterrupted power, you’ll need to add a backup batter system.
These allow you to store solar energy and use it when the grid goes down, helping you keep the lights on and your home running. We’ll explain everything you need to know about solar power battery backup systems below.
Why Most Solar Systems Shut Down During Power Outages
Many homeowners are surprised to learn that most solar systems don’t power their homes during a power outage. After all, if the system is actively producing power, why can’t you use it?
While it might seem counterintuitive, the design is intentional. If your solar system continued sending electricity into the grid during an outage, it could create dangerous conditions for utility crews repairing power lines. To prevent that, grid-connected systems are built to disconnect automatically whenever they detect the grid is offline.
Without somewhere to safely send or store the electricity your panels produce, the system simply stays disconnected until utility power returns.
A battery changes how the system responds. Instead of shutting everything down, your system just temporarily disconnects from the grid and continues producing usable electricity. That keeps power flowing, which means you can keep your home — or at least part of it — up and running.
How Solar Batteries Keep Your Home Running
A solar battery works much like any other battery: it stores power. It’s like a bigger version of the portable battery you use to charge your phone.
During the day, your solar panels may generate more electricity than your home is using. Without a battery, much of that excess energy is sent back to the utility grid. A battery stores it instead, allowing you to use that electricity after the sun goes down or when your home’s energy needs temporarily exceed what your panels are producing.
That stored energy becomes especially valuable during a power outage. When the utility grid falters, your battery system temporarily disconnects your home from the grid, allowing your solar panels to continue producing usable electricity.
Your home uses the power it needs first, while any excess energy can recharge the battery. If your panels aren’t producing enough electricity, or the sun has gone down, the battery supplies the difference.
What Kinds of Systems Can a Solar Battery Power?
Exactly what your solar battery can power depends on three main things: the size of the battery, how much electricity your home uses, and how your system is configured.
Many homeowners choose to back up only their essential circuits. That usually includes things like:
- Refrigerator and freezer
- Interior lighting
- Wi-Fi router and internet equipment
- TV and device chargers
- Garage door opener
- Security system
- Medical equipment
- A kitchen outlet or two
If you have a bigger battery system, it might be able to keep up with high-demand appliances, such as your central air conditioner or well pump. Keep in mind, though, that those appliances drain stored energy much faster than something like your overhead lights or internet router.
So, when designing a solar-plus-storage system, we look at what you want to keep running during an outage. If you just want to keep the fridge, a few lights, and your Wi-Fi router on, a single battery might be enough. If you want your battery to pick up right where the grid left off, you’ll likely need a bigger battery bank.
How Long Does Battery Backup Last?
The length of time a battery backup will last depends on the devices you’re using it to power.
If you’ve set up your system to back up a few essentials — your lights, Wi-Fi, refrigerators, and a couple of outlets — your battery might keep those circuits running for many hours or even a full day.
Now, if you’re trying to power bigger appliances like central AC or an electric water heater, you’ll burn through that stored energy much faster. Unless you have multiple batteries, it could only be a few hours before your battery runs out.
The weather factors in here, too. During a sunny outage, your panels can continue generating electricity, giving you a steady supply that helps power your home and recharge the battery with any excess energy.
With enough sunshine and careful energy use, some homeowners can stretch their backup power for several days. Once the sun goes down, though, you’ll have to fall back on whatever your battery has stored until daylight returns or the grid comes back online.
How Much Does Solar Battery Backup Cost?
For many homeowners, the biggest question is less about whether or not a battery backup is useful — after all, who can argue with backup power — and more about whether the added cost makes sense.
Unlike solar panels, which are typically priced by the watt, batteries are usually priced by their storage capacity, measured in kilowatt-hours (kWh). On average, homeowners can expect to pay between $600 and $1,700 per kilowatt-hour of storage, though the exact price varies by the manufacturer, installation requirements, and local labor costs.
For example, here’s what a battery backup, set at California’s average price of about $1,000 per kilowatt-hour, would cost:
| Battery Size | Estimated Cost |
| 5 kWh | $5,000 |
| 10 kWh | $10,000 |
| 15 kWh | $15,000 |
Note: These are simply estimates based on average per kWh rates in California. Actual costs may vary.
Solar Battery vs. Whole-Home Generator
Both solar batteries and whole-home generators provide backup power during an outage, but they do it in different ways.
A battery stores electricity generated by your solar panels or the utility grid and automatically powers your home when the grid goes down. Because it doesn’t rely on gasoline, propane, or natural gas, it works quietly and produces no on-site emissions.
A whole-home generator, on the other hand, generates electricity using a fuel source. Many standby generators run on natural gas or propane and can supply power for as long as fuel remains available. They also usually handle large electrical loads, like your central AC unit, more easily.
Here’s how the two compare:
| Feature | Solar Battery | Whole-Home Generator |
| Power source | Stored electricity | Natural gas or propane |
| Noise | Quiet | Audible while running |
| Fuel required | No | Yes |
| Emissions | None during operation | Produces exhaust |
| Works with solar | Yes | No |
| Best for | Quiet, renewable backup power | Long outages and high electrical demand |
Neither of these options is universally better. If you already have solar panels or want to maximize your use of renewable energy, a battery backup is a great choice.
If you’d rather power every circuit in your home through long outages without having to worry about whether the sun’s shining, a whole-home generator may make more sense.
Is Battery Backup Right for Your Home?
If keeping the lights on during one of California’s blackouts is a priority, battery backup is worth considering. You might be a good candidate if you:
- Experience frequent power outages
- Already have, or plan to install, solar panels
- Work from home and rely on a stable internet connection
- Have refrigerated medications or other essential medical equipment
- Want to keep your refrigerator, lights, and other critical circuits running during a blackout
- Prefer a quieter, lower-maintenance alternative to a generator
Frequently Asked Questions
If you’re still on the fence about whether a solar battery is right for your home, these answers may help clear up a few common questions.
Does solar automatically work during a power outage?
Not usually. For safety reasons, most grid-tied solar systems automatically shut down when the utility grid loses power. A battery backup lets your home safely disconnect from the grid and continue using stored energy during an outage.
Can I add a battery to my existing solar system?
Yep, you typically can. Many solar systems can be upgraded with battery storage, even years after they’re installed. The exact process looks a little different based on your equipment.
How many batteries do I need?
That depends on what you want to keep running. If you only want to power the essentials — think your fridge and lights — one battery might be enough. To keep your whole home running, you’ll likely need additional battery capacity.
Will a solar battery power my air conditioner?
It can, but air conditioners use a lot of electricity. Running central AC or charging your EV will drain a battery much faster than powering essentials like lights or your refrigerator. If you want your AC to stay on during an outage, you’ll probably need additional battery storage.
How long do solar batteries last?
Most lithium-ion solar batteries are designed to last 10 to 15 years. Many manufacturers also back their batteries with warranties of around 10 years. The exact amount of time your battery lasts will vary based on usage and environmental conditions.
Will my battery recharge during a power outage?
Yes, as long as your solar panels are generating more electricity than your home is using. During a sunny outage, any excess solar energy can recharge the battery, helping extend your available backup power.
Are there rebates or incentives available for solar batteries?
Often, yes. Eligible battery storage systems may qualify for programs like the Self-Generation Incentive Program (SGIP). This program provides up to $1,000 per kilowatt-hour for eligible systems, which means an energy storage system for your home can be more affordable (sometimes even free).
Talk With a Solar Battery Expert
Choosing the right battery starts with understanding how you use electricity. The appliances you want to power, how long you want backup power to last, and your existing electrical system will determine what kind of setup fits your needs.
Our team can help you find that setup. We’ll assess your home’s energy needs, answer your questions, and recommend a setup that fits how you use electricity. Contact Fisher Electric today to schedule a consultation.
Sources & References
- California Public Utilities Commission (CPUC) – Self-Generation Incentive Program (SGIP)
Explains California’s Self-Generation Incentive Program, including eligibility requirements, available rebates for battery storage systems, participating installers, and how homeowners can apply for incentives that help offset the cost of energy storage.
https://www.cpuc.ca.gov/industries-and-topics/electrical-energy/demand-side-management/self-generation-incentive-program/participating-in-self-generation-incentive-program-sgip - EnergySage – How Much Do Solar Batteries Cost?
Provides an overview of residential solar battery pricing, including average cost per kilowatt-hour, factors that affect installation costs, typical battery capacities, and available incentives.
https://www.energysage.com/energy-storage/how-much-do-batteries-cost - U.S. Department of Energy – Solar Integration: Solar Energy and Storage Basics
Explains how solar energy storage works, why batteries improve grid resilience, how stored energy is used during outages, and the role battery systems play in maximizing the value of residential solar installations.
https://www.energy.gov/cmei/systems/solar-integration-solar-energy-and-storage-basics
