Does solar work during a power outage
Why most grid-tied solar shuts off in a blackout, and your options for backup power: batteries, backup-ready inverters and generators.
5 min read · Updated 2026-10-30
Many people are surprised to learn that a typical rooftop solar system goes dark during a power outage, even on a sunny day. This is by design, and it protects the people repairing the grid. If keeping the lights on during outages matters to you, you need extra equipment. This guide explains why the system shuts down and what your realistic options are.
Why grid-tied solar shuts off
Most Canadian home solar systems are grid-tied. They connect to the utility grid through your electrical panel and have no battery.
When the grid goes down, the inverter detects the loss of grid power and shuts the system off within a fraction of a second. This is called anti-islanding. Without it, your panels could keep feeding power into the street lines. Line workers repairing a downed wire expect it to be dead. Power flowing back from homes could injure or kill them.
Anti-islanding protection is required for any system connected to the grid. Your system turns back on automatically a few minutes after grid power returns.
Outages in Canada
Most outages are short, but long ones do happen. The May 2022 derecho that tore across southern Ontario broke a record 1,900 Hydro One poles, and the utility restored power to more than 652,000 customers over the following days, with some rural areas waiting much longer. Ice storms, windstorms and wildfires cause long outages in other provinces too.
How much backup you need depends on how often you lose power, for how long, and what you need to keep running. A home with a sump pump, a well pump or medical equipment has different needs from a city home that loses power once a year for an hour.
Option 1: a home battery with backup
A battery stores electricity and, with the right equipment, can power part or all of your home when the grid is down. When paired with solar, the panels can recharge the battery during the day, so a long outage in summer is much easier to ride out.
What it takes:
- A battery and an inverter able to run in backup mode.
- A device that disconnects your home from the grid during an outage, so you can safely run without backfeeding the lines.
- Usually a separate backup (critical loads) panel with the circuits you choose to keep running.
Many popular home batteries store roughly 10 to 15 kWh. What that can run depends on what you plug into it. Our guide on batteries explained covers how they work.
What a battery can realistically run
| Load | Realistic on one battery |
|---|---|
| Fridge and freezer | Yes, they use a modest amount spread over the day |
| Lights, internet, phone and laptop charging | Yes, very little energy |
| Gas furnace fan | Usually, for a good while |
| Sump pump or well pump | Usually, but check the startup power |
| Central air conditioning | Briefly, if the battery and inverter are big enough |
| Electric baseboard or electric furnace heat | Only for a short time; far more energy than one battery holds |
| EV charging, electric dryer, oven | Not practical during an outage |
Running only essentials, a single battery can often last a day or more, longer if solar can recharge it. Trying to run a whole house with electric heat in January will drain it in hours.
In Ontario, the Home Renovation Savings Program offers up to $5,000 toward a battery (up to 50% of cost) when it’s installed together with new solar. See incentives and home battery cost and payback.
Option 2: a backup-capable inverter
Some inverters can supply a limited amount of power from the panels during an outage, only while the sun is shining, without a battery. A typical example is a single dedicated outlet on the inverter.
This can charge phones or run a small appliance on a sunny afternoon. It won't run your fridge overnight or help on a cloudy day. It is a handy extra. It won't replace real backup.
If you might add a battery later, ask installers whether the inverter you are buying can accept one. This is sometimes called a hybrid or battery-ready inverter. Choosing one now can save you from replacing equipment later.
Option 3: a generator
A generator is often the cheapest way to get backup power, especially for long winter outages when solar produces little.
- Portable generators run selected appliances through extension cords or through a transfer switch installed by a licensed electrician.
- Standby generators run on natural gas or propane and start automatically.
Generators must never be connected by plugging them into a household outlet or wiring them straight into your panel without a proper transfer device. That can backfeed the grid and endanger line workers, just like an unprotected solar system. Ontario's Electrical Safety Authority warns about exactly this. Never run a generator indoors or in a garage, because exhaust contains deadly carbon monoxide.
If you have solar and a generator, tell your electrician and installer. The two need to be set up so they don't interfere with each other.
Which option fits
- Rare, short outages: you may not need backup at all. A few flashlights and a battery pack for phones go a long way.
- Sump pump, well or medical needs: a battery or generator is worth serious thought, with or without solar.
- Long winter outages: a generator is usually the most reliable choice. Solar recharges a battery slowly on short, snowy days.
- Frequent outages and a wish to stay quiet and fuel-free: solar plus a battery.
Be wary of anyone selling a battery mainly as a money-saver. In most of Canada, people buy batteries for backup. Payback on savings alone is rare. See solar scams and red flags.
Next step
See what solar alone would save on your bill, then decide whether backup is worth adding: check your roof.
Common questions
- Do solar panels work during a power outage?
- Not on a standard grid-tied system. The inverter shuts off when the grid goes down to protect line workers, unless you add a battery or other backup equipment.
- What is anti-islanding?
- It is a safety feature that shuts off a solar system when the grid loses power. It stops your panels from sending electricity into lines that workers believe are dead.
- How long will a home battery last in an outage?
- Running essentials like the fridge, lights, internet and furnace fan, a single 10 to 15 kWh battery can often last a day or more. Electric heating drains it in hours.
- Can I use a generator with solar panels?
- Yes, if a licensed electrician installs a proper transfer device so the generator can't backfeed the grid. Tell your installer so the systems are set up to work together.
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