Standard grid-tied solar panels usually do not provide electricity during a blackout. Even when the sun is shining, most solar inverters shut down when the utility grid fails. They do this to prevent electricity from flowing into power lines while utility workers may be repairing them.
As of ****, the answer depends on the equipment installed with the panels. A backup system typically needs a battery, a backup-capable inverter and equipment that disconnects the home from the grid.
What Happens to Solar Panels During a Power Outage?
A typical rooftop solar system works with the utility grid:
- Solar panels produce direct-current electricity.
- An inverter converts it into alternating-current electricity for the home.
- The inverter synchronizes with the utility grid.
- If the grid fails, the inverter disconnects and shuts down.
This safety feature is called anti-islanding protection. It stops a solar system from sending electricity onto power lines that utility workers may believe are de-energised.
The panels may still receive sunlight and generate electricity internally, but a standard grid-tied system will not normally deliver usable power to the home during the blackout.
Can Solar Panels Work During a Blackout with a Battery?
Yes. Solar panels can provide backup electricity during a blackout when they are connected to a compatible battery and backup inverter.
During an outage, the system:
- Disconnects the home from the utility grid
- Creates a separate electrical network for the home
- Uses stored battery energy to power connected circuits
- Uses solar power to recharge the battery when conditions allow
The U.S. Department of Energy says solar panels need a properly configured inverter and an energy storage system to operate independently from the grid.
Depending on the installation, the battery may power selected circuits such as refrigerators, lights, internet equipment and medical devices. Some systems can provide whole-home backup. The result depends on the battery capacity, inverter rating, electrical panel configuration and household demand.
Solar Panels Versus Solar Panels with Battery Backup
| Solar system type | Works during a blackout? | What it can do |
|---|---|---|
| Standard grid-tied solar panels | No | Shuts down when the grid fails |
| Grid-tied solar with battery storage | Yes | Powers selected circuits or the whole home, depending on the design |
| Off-grid solar system | Yes | Operates independently with batteries and off-grid equipment |
| Portable solar generator | Yes | Powers connected devices within its output and battery limits |
| Solar panels with a standard generator | Sometimes | Requires compatible switching and electrical installation |
A battery alone is not enough. The system also needs an inverter that can create a stable local electrical network and equipment that isolates the home from utility lines. Some inverters are designed to operate without the grid during an outage.
How Long Will Solar Power Last During a Blackout?
There is no standard runtime for a solar and battery system. It depends on:
- Battery size and remaining charge
- Solar production
- Weather and shade
- Household electricity use
- Whether large appliances are running
- Whether the system backs up the whole home or only essential circuits
During the day, the panels may run appliances and recharge the battery. At night, the battery supplies the electricity.
If the panels produce more electricity than the home is using and the battery cannot store the excess, some systems reduce or temporarily stop solar production. This protects the backup system from excess power.
How to Tell Whether Your Solar System Works During Outages
Check whether the installation includes:
- A home battery, such as Tesla Powerwall or another compatible battery
- A backup gateway, transfer switch or automatic isolation equipment
- An inverter rated for off-grid or backup operation
- A clearly labeled backup-loads panel
- Installation documentation that explains outage operation
Your solar monitoring app may also show whether the system supports backup power. If you are unsure, check the inverter model or contact the installer. Do not assume that rooftop panels can provide emergency electricity just because they are producing power in direct sunlight.