Do solar panels work during a power outage?
Usually not. Most home solar systems are grid-tied, so the panels shut off when the grid goes down, even on a sunny afternoon. A solar system with a battery and backup equipment can keep your home running. Solar panels alone cannot. Here is why, and how to tell which kind you have.
This matters in Southern California, where utilities such as SCE sometimes switch off power on purpose during high winds to lower wildfire risk. When that happens, every home on the affected circuits loses power, including homes with solar. You can see how it played out in our recap of the October 2026 Southern California power shutoffs.
Why solar shuts off without a battery
Most rooftop systems are grid-tied. They send power to the grid and lean on it. The U.S. Department of Energy says these systems generally depend on the grid to produce power and are designed to switch off if grid power cuts out.
The reason is safety. When a line goes down, utility crews work on it assuming it is dead. If a home system kept pushing power into that line, the power could flow back onto it and put the crew in danger. That situation is called islanding, and the shutoff feature that prevents it is called anti-islanding. Palmetto notes that UL 1741, a safety standard, requires every grid-tied system to have an inverter with built-in anti-islanding protection.
The inverter is the box that converts your panels’ power into the electricity your home uses. EnergySage explains that it watches for the grid’s signal. The moment that signal disappears, it cuts off production within a couple of seconds and stays off until the grid returns.
So the shutoff is deliberate. Your panels are not broken, and your system is doing what it was built to do. It just means a system without a battery gives you nothing during a blackout, even in full sun.
If you are also wondering about earthquakes, we cover that separately in Can Solar Panels Still Work After an Earthquake?
What changes with a battery and backup gateway
A battery stores energy. A gateway (some systems use a backup switch) is the piece that notices the outage and separates your home from the grid. Tesla says a Powerwall 3 is installed with a Backup Switch, Backup Gateway 2 or Gateway 3 to control the system’s connection to the grid, and that the gateway handles outage detection.
Once your home is separated from the grid, it becomes its own small system. The Department of Energy calls this an “islanded” mode. EnergySage compares it to a small microgrid. Because it is no longer connected to the lines crews are working on, it is safe for it to keep running. The Department of Energy adds that panels alone are not enough: you need a properly configured inverter and a storage system.
[IMAGE 2, flow graphic: post2-what-happens-flow.png (1200 x 700). Place here. Alt text: Flow chart showing that with no battery, solar panels shut off when the grid goes down, while a home with a battery and backup gateway disconnects from the grid and runs on the battery, recharging from solar in the daytime]
Two choices shape what you get:
- Whole home backup. Tesla describes this as powering the entire home during an outage.
- Partial backup. Selected circuits, such as the fridge, lights and internet, are backed up. Tesla says these loads are chosen when the system is designed, and the installer excludes everything else.
There is also a smaller option. EnergySage says some solar systems have backup-capable equipment that can power a few small loads during a sunny daytime outage, but these do not run a fridge overnight. If a quote mentions this kind of backup, ask exactly what it covers.
Will the battery charge during an outage?
Often, yes, if the system is set up for it and the sun is out. Tesla says a Powerwall can recharge from your solar system to run your home from solar and Powerwall even when the grid is down. When the panels make more than the home and battery can use, the Powerwall tells the inverter to scale back, which typically happens as the battery nears full.
At night, or under heavy cloud, the panels make little or nothing and the battery draws down. The Department of Energy says solar with storage can keep delivering power through a long outage, even at night. Tesla adds that if a Powerwall’s charge falls below 10%, it goes into standby and tries to recharge from solar when the sun is up.
A few habits from Tesla’s outage guidance stretch your battery further:
- Cut back on energy-hungry appliances, such as air conditioning.
- Do heavy tasks, like laundry, before the outage if you have warning.
- Keep your panels clear of debris so they can charge the battery.
Solar only vs solar plus battery
| Solar panels only (grid-tied) | Solar plus battery with a backup gateway | |
|---|---|---|
| Power in your home during an outage | None. The panels switch off within seconds. | Yes, for the loads the system is set up to back up. |
| Why | Anti-islanding protects utility crews working on the lines. | The home separates from the grid, so it can run on its own. |
| On a sunny day | No power, even in full sun. | Panels can power the home and recharge the battery. |
| At night | No power. | The battery supplies power until it runs low. |
| What gets power | Nothing. | Whole home or selected circuits, chosen at design. |
| Equipment | Panels and inverter. | Panels, inverter, battery, and a gateway or backup switch. |
What can a battery power during an outage?
It depends on three things: how many batteries you have, how much your home uses, and whether the system backs up the whole home or selected circuits.
Two numbers help here. Kilowatt-hours (kWh) show how much energy a battery stores. Kilowatts (kW) show how much power it can deliver at one moment. Tesla rates a single Powerwall 3 at 13.5 kWh of nominal energy and 11.5 kW of continuous discharge power, and each Powerwall 3 Expansion unit adds another 13.5 kWh.
[IMAGE 3, graphic: post2-powerwall3-specs.png (1200 x 560). Place here. Alt text: Three tiles showing Tesla Powerwall 3 ratings: 13.5 kWh nominal battery energy, 11.5 kW maximum continuous discharge power, and 13.5 kWh added by each expansion unit]
EnergySage says one battery paired with solar can typically keep essentials like a refrigerator, a Wi-Fi router and a few lights running for a day or two, and that whole-home backup generally takes two or more batteries. Your own result depends on your loads, so treat that as a rough guide.
For a closer look, read What Can a Powerwall 3 Run During an Outage? and How Long Can a Home Battery Power Your House? If you are weighing a battery against a generator, see Generator vs Battery Backup.
How to add a battery to solar you already have
If you already have panels, you may not have to start over. Whether a battery can be added depends on your inverter, the age of your system and your electrical panel, so HomeLink Solar checks those before quoting. Our guide on how to add a battery to existing solar in California walks through the options.
To find out what your system does today, ask your installer or check your paperwork for three things:
- Is there a battery?
- Is there a backup gateway or backup switch?
- Does it back up the whole home or selected circuits?
If you have panels and no battery, assume your system shuts off when the grid goes down.
HomeLink Solar installs with our own crews, with no subcontractors, under CSLB license #1117534. Our Power Choice program for SCE customers and Solar Plus program for SDG&E customers pair solar with a Tesla Powerwall 3. For the full picture, see our complete guide to solar battery backup in Southern California.
Want backup on your solar? Add backup to your solar with a free quote.
FAQs
Do solar panels work during a power outage?
Usually not. Standard grid-tied solar shuts off when the grid goes down. Solar works during an outage only if the system also has a battery and backup equipment.
Why does solar shut off during a blackout?
Grid-tied systems stop producing so they do not push electricity onto lines that utility crews believe are dead. This protects workers, and it is built into the inverter.
Can you use solar during a power outage?
Yes, if your system has a battery and a gateway or backup switch that separates your home from the grid. Without them, you cannot.
Will a solar battery charge during an outage?
If the system is set up for backup and the sun is out, solar can recharge the battery. At night or in heavy cloud, the battery draws down.
Will a battery keep my whole home on?
It depends on how many batteries you have, how much your home uses, and whether the system backs up the whole home or selected circuits. See What Can a Powerwall 3 Run During an Outage?
Can I add a battery to the solar I already have?
Often, yes. HomeLink checks your existing inverter and panel setup first. See how to add a battery to existing solar.
Sources
- U.S. Department of Energy: Solar and Resilience Basics
- EnergySage: Do Solar Panels Work During a Power Outage? (updated Aug 11, 2026)
- Palmetto: What Is Solar Islanding and Anti-Islanding?
- Tesla Support: How Powerwall Works
- Tesla Support: Powerwall System Design
- Tesla Support: Best Practices During Power Outages
- Tesla: Powerwall 3 Owner’s Manual, System Design
- Tesla: Powerwall 3 Datasheet
