Batteries & backup
Does my solar produce when the grid is off?
The honest answer is no — unless you have a battery. Here is why grid-tied solar shuts down during an outage, and what it actually takes to keep the lights on.
The short answer — and why it’s a feature, not a defect
A standard grid-tied solar system, which is panels and an inverter with no battery, stops producing the moment the grid goes down. This is true even at noon when the sun is shining and during the peak of summer in July. If nobody told you that before you bought, it feels like something is broken. Rest assured your system is operating as it should.
Your inverter is required to shut down in an outage. The rule is called anti-islanding, and when a power line goes dark, utility crews go to work on it to restore power as quickly as possible. If a solar system that kept pushing power was allowed to send power out to the grid, that power would turn a de-energized wire into a live one.
As a result, inverters are required to detect a grid outage and stop exporting within about two seconds (NREL’s plain-language summary). Every certified inverter sold in the U.S. is built and tested to do exactly this.
Net is that your system on your roof isn’t failing during an outage — it’s protecting the person working to restore the power.
What an outage actually looks like for you
The sequence is quick: the grid drops, your inverter senses it within seconds, and production goes to zero. Your monitoring app will show a flat line — that’s the system doing its job, and not a fault to troubleshoot or worry about.
The opposite is also automatic. When utility power comes back and holds steady, your inverter waits a few minutes to ensure voltage stays consistent and then restarts on its own. If your system hasn’t restarted within about half an hour of stable grid power, that’s when our post-outage checklist is worth a look.
What a battery actually changes
A battery system changes the answer because it changes the way your home manages that grid-tied connection. Battery systems built for backup include islanding hardware. The device that does that is a gateway or transfer switch that physically disconnects your home from the grid during an outage. Once your home is its own electrical island, the safety problem disappears: your panels can’t energize the utility’s lines because you’re no longer connected to them. The panels keep producing, the battery fills and empties, and the backed-up parts of your home stay on (DOE: solar and storage basics).
A couple nuances to be aware of. First, backup comes in different forms and the amount of backup informs the design. An essential-load setup keeps the refrigerator, lights, internet, and some outlets running, while whole-home backup, especially with central air conditioning in the mix, requires substantially more battery capacity. Second, with solar recharging the battery every day, a properly configured setup can ride through a multi-day outage — but the math depends entirely on what you’re powering.
One niche exception worth knowing: a handful of inverters offer a small “sun-only” outlet that provides limited power during a daytime outage without a battery. It can charge phones and run a fridge while the sun is up — it is not whole-home backup, and most systems don’t have it.
In California and Texas, this isn’t hypothetical
In California, utilities de-energize lines on purpose during high fire-risk weather — Public Safety Power Shutoffs, which cluster in late summer and fall (CPUC). A PSPS is exactly the scenario above: grid off, solar-only systems off with it, battery homes riding through.
Texas doesn’t need a reminder of February 2021. Winter Storm Uri forced the largest manually controlled load shed in U.S. history — about 20,000 MW of rolling outages — per the FERC/NERC final report. Solar-only homes were dark like everyone else; that winter is a large part of why Texas battery attachment rates have climbed since.
We’ve written a deeper Texas-specific guide here: Texas grid outages and home battery backup.
So — do you need a battery?
It depends, and anyone who answers before asking about your situation is selling, not advising. The case for backup is strongest when outages in your area are real and recurring, when someone in the home depends on powered medical equipment, or when you work from home and downtime is impactful. If your grid is boring and reliable, backup is a comfort purchase — which is a legitimate reason, as long as you’re making it knowingly.
Batteries can also earn savings under time-of-use rates and net-billing rules — that’s a separate question from backup, and it deserves its own explanation. Don’t let the two get blended together too much.
If you want to see what backup would look like for your home — how many batteries, what they’d cover, and what the full system pencils out to — Build Your System models it with the same honest assumptions we use everywhere else.
Run your own payback — in about two minutes.
Plug in your roof and your usage. Build Your System models it with realistic assumptions — degradation, rate inflation, and fees included — so the number is one you can stand on. No pressure, no salesperson.
Sources
We back up what we publish. The standards and reports behind this article:
U.S. Department of Energy — Solar integration: solar energy and storage basics
California Public Utilities Commission — Public Safety Power Shutoffs
FERC/NERC — Final report on the February 2021 cold weather outages (Winter Storm Uri)
Frequently asked questions
Do solar panels work during a power outage?
Not on a standard grid-tied system without a battery. Inverters are required by the IEEE 1547 interconnection standard to shut down within seconds of a grid outage so they can’t energize lines utility crews are repairing. A battery system with islanding hardware is what keeps solar producing during an outage.
Why does my solar system shut off when the power goes out?
It’s a mandatory safety feature called anti-islanding. When the grid goes down, line workers assume wires are de-energized. Your inverter disconnects automatically so your panels can’t back-feed the grid — every certified inverter in the U.S. is tested to do this.
Will my solar system turn back on by itself after an outage?
Yes. Once grid power returns and holds steady, your inverter waits a few minutes and restarts automatically — no breaker or service call needed. If production hasn’t returned within about half an hour of stable power, run through a post-outage check or call for service.
Can I add a battery to my existing solar system?
Usually yes. AC-coupled batteries retrofit onto most existing systems regardless of inverter brand, and that’s the most common path. The right battery and configuration depend on your equipment and what you want backed up — an assessment sorts that out quickly.
How long can a solar battery power my house?
It depends on what you back up. An essential-loads setup — fridge, lights, internet, outlets — can run overnight on a single battery and ride through multi-day outages with solar recharging it each day. Whole-home backup with central air conditioning drains batteries far faster and usually takes multiple units.
Get straight answers for your home.
Reading up is smart. When you’re ready, tell us about your home and we’ll give you honest, local numbers — no pressure.
Get a quote