If the power just went out and your solar panels aren’t doing anything about it, that’s not a malfunction. It’s how the system is designed to work without battery backup, and it surprises a lot of homeowners who assumed solar alone meant automatic power during an outage.
Why Grid-Tied Solar Shuts Off During an Outage
Most residential solar systems are “grid-tied,” meaning they’re connected to your utility’s distribution network. When the grid goes down, California’s Electric Rule 21 — the interconnection tariff the CPUC requires for any generation system connected to a utility’s grid — requires that grid-tied inverters automatically disconnect rather than continue sending power into the lines. This is a safety requirement, not a design flaw.
The reason is straightforward: utility crews need to know a downed line is actually dead before they touch it. If your solar system kept feeding power into the grid during an outage, it could re-energize a line a crew believes is safe, which is a serious safety hazard. Every grid-tied inverter sold in the U.S. includes this automatic shutoff, sometimes called “anti-islanding,” as a built-in, non-optional feature.
What This Means in Practice
If your system is grid-tied without battery storage, your panels stop producing usable power for your home the moment the grid goes down — even if the sun is shining. Once utility power is restored, the inverter automatically reconnects and resumes normal operation after a short delay.
This isn’t unique to any brand or installer. It applies to every standard grid-tied system, regardless of who installed it or how new the equipment is.
What Actually Provides Backup Power
The only way to keep power flowing during an outage is to add battery storage with an inverter designed to “island” your home — disconnecting from the grid while continuing to draw from the battery and your solar production. This is a different system design than a standard grid-tied setup, and it needs to be planned for specifically rather than assumed.
If outage protection matters to you and your current system doesn’t have it, that’s a retrofit question worth asking a solar contractor directly rather than assuming your existing panels already cover it.
If you’d like to know what it would take to add real outage protection to your existing system, Pacific Solar can walk through what your current setup supports and what a battery retrofit would look like.
Tired of losing power when the grid does? Ask Pacific Solar about a battery backup retrofit for your existing system.
Frequently Asked Questions
Will adding a battery fix this? Yes, if the battery and inverter are configured for islanding. Not every battery installation is automatically set up for outage backup — confirm this specifically when you’re getting a battery quote.
Is this the same for every solar installer’s equipment? Yes. The shutoff requirement comes from CPUC Rule 21 and applies to any grid-tied system interconnected in California, regardless of installer or equipment brand.
How do I know if my system has backup capability already? Check whether your system includes a battery and a specific backup or “islanding” mode. If you’re not sure, your monitoring app or your installer’s paperwork should specify this — or you can ask directly.