What Happens to Solar Panels During a Power Outage?

Here is the part most Houston homeowners find out too late: if the grid goes down, a standard grid-tied solar system shuts down too. Your panels can be in full August sun, producing nothing, while the house sits dark.

This is not a defect. It is a safety requirement — and there is a way around it.

Why your solar switches off

Grid-tied inverters are required to include anti-islanding protection, mandated by UL 1741 and the National Electrical Code.

The reasoning is straightforward. When your array produces more than the house consumes, the surplus flows back onto the grid. During an outage, line workers are repairing conductors they have confirmed are dead. A solar system still pushing power onto those lines would energise them without warning — a genuine electrocution risk.

So the moment the inverter stops sensing grid voltage, it disconnects within seconds and stays off until the grid returns and stabilises. Every compliant grid-tied system in Houston behaves this way. There is no override, and you would not want one.

What actually keeps your lights on

Battery storage. A battery lets your system form its own grid inside the house.

When utility power fails, an automatic transfer switch isolates your home from the grid within milliseconds. Your battery then supplies the house, and — importantly — your solar can keep charging that battery. Because the house is now electrically islanded from the grid, no power flows outward and the safety issue disappears.

That combination is what gets you through a multi-day hurricane outage: the battery carries you overnight, and the panels refill it each day.

Sizing a battery for Houston outages

Most Houston homeowners size for essential loads rather than whole-home backup, because air conditioning is the difficult part.

A typical 13.5 kWh battery comfortably runs a refrigerator, lights, internet, phone charging, a few outlets and some fans for 12–24 hours. Add a second battery and you approach two or three days on essentials.

Central AC is the honest constraint. A modern high-efficiency or variable-speed unit can run on battery for limited stretches; an older single-stage compressor draws hard on startup and will drain storage fast. Many Houston households back up a single mini-split or a couple of window units for one room rather than trying to cool the whole house.

Given ERCOT grid events and Gulf hurricane season, outage resilience is the main reason Houston customers add storage — the bill savings are secondary.

What about a partial workaround?

Some inverters offer a limited daytime backup outlet — a single circuit producing perhaps 1.4 kW while the sun is up, with nothing at night. It will charge phones and run a fan. It is not home backup, and it only works on models specifically built for it.

Planning ahead even if you skip the battery now

Storage is considerably cheaper to add when it was anticipated in the original design. Ask for a battery-ready hybrid inverter and a backup-loads subpanel during the design stage. That way, adding a battery in three years is a straightforward retrofit rather than an inverter replacement.

Tell your designer during the system design step if backup power is even a maybe.

The short version

• Solar alone: no power during an outage, by design and by law.
• Solar plus battery: essentials run through outages, recharging daily from the sun.
• Battery-ready inverter: keeps the option open cheaply.

Read more about our battery storage installations, or ask us to model outage backup for your home.