Solar Panels During a Power OutageWhat Actually Happens (and How to Fix It)
If you have solar panels without a battery, your system shuts off completely during a grid outage. Here is why that happens, what your options are, and how much battery backup actually costs in 2026.
The Short Answer
Standard grid-tied solar panels cannot power your home during an outage. Federal safety standards (UL 1741) require solar inverters to shut down when the grid goes down, preventing electrocution of utility workers. To have power during outages, you need a battery backup system ($10,000-$16,000 installed) that creates a local microgrid for your home.
Why Grid-Tied Solar Shuts Off During Outages
It seems counterintuitive: the sun is shining, your panels are on the roof, but your house has no power. The reason is a safety requirement called anti-islanding protection.
How Anti-Islanding Works
Grid goes down
A storm, transformer failure, or utility maintenance causes a power outage.
Inverter detects loss of grid signal
Your solar inverter constantly monitors grid voltage and frequency. When it detects an abnormality, it acts within milliseconds.
Inverter shuts down (UL 1741 / IEEE 1547)
Federal standards require the inverter to disconnect within 2 seconds. This prevents your panels from energizing downed power lines.
Your home loses all power
Without the grid or a battery to form a microgrid, your solar panels produce zero usable electricity.
This is a safety feature, not a flaw. If your solar panels continued sending electricity into the grid during an outage, utility workers repairing downed lines could be electrocuted. Anti-islanding has saved lives.
The Solution: Battery Backup Systems
A battery backup system solves the outage problem by creating a local microgrid for your home. When the grid goes down, the battery inverter disconnects from the grid and forms an independent power island. Your solar panels charge the battery, and the battery powers your home.
How It Works During an Outage
Daytime
Solar panels generate electricity, power your home directly, and charge the battery for nighttime use.
Nighttime
Battery discharges stored energy to power your home. A 13.5 kWh battery runs essential loads for 12-24 hours.
Extended Outage
Solar recharges battery each day. Potentially unlimited backup with solar + battery during sunny weather.
Best Home Batteries for Backup (2026)
Here are the top battery systems we install, with 2026 pricing and specifications. All prices include installation. Note: the federal residential tax credit (Section 25D) expired in 2025, so battery purchases no longer qualify for a federal credit.
| Battery | Capacity | Power Output | Installed Price |
|---|---|---|---|
| Enphase IQ 5P | 5 kWh | 3.84 kW | $6,500-$8,000 |
| Tesla Powerwall 3 | 13.5 kWh | 11.5 kW continuous | $12,000-$14,500 |
| FranklinWH aPower2 | 13.6 kWh | 10 kW continuous | $13,000-$16,000 |
| Enphase IQ 10C | 10 kWh | 3.84 kW | $10,000-$12,000 |
Prices as of March 2026. Includes standard installation. Complex electrical upgrades may add $500-$2,000.
Whole-Home vs. Essential-Load Backup
Essential-Load Backup
Powers only critical circuits during an outage.
- Refrigerator/freezer
- Lights (select rooms)
- Wi-Fi router + phone chargers
- Sump pump (if applicable)
- Medical equipment
Battery needed: 5-10 kWh
Runtime: 12-24+ hours
Cost: $6,500-$12,000
Whole-Home Backup
Powers your entire home including high-draw appliances.
- Everything in essential loads, plus:
- Central HVAC / heat pump
- Electric stove/oven
- Washer/dryer
- EV charger (if applicable)
Battery needed: 13.5-27 kWh
Runtime: 6-12 hours
Cost: $12,000-$28,000
ConnectedSolutions: Earn Revenue from Your Battery
If you live in Massachusetts, Rhode Island, or Connecticut, your battery can earn annual revenue through utility demand response programs. Your utility pays you to discharge your battery during peak demand events (typically 10-20 events per summer).
Eversource (MA)
$275/kW
Summer + $50/kW winter
13.5 kW battery = ~$1,350/yr
National Grid (MA/RI)
$225/kW
Summer + $50/kW winter
13.5 kW battery = ~$1,100/yr
RI Energy
$225/kW
Summer demand response
13.5 kW battery = ~$1,080/yr
At $1,000-$1,350 per year, ConnectedSolutions revenue can offset 30-40% of your battery cost over its 10-15 year warranty period. Combined with outage protection, this makes battery storage a compelling investment even without the federal tax credit.
Frequently Asked Questions
Why do solar panels shut off during a power outage?
Grid-tied solar inverters are required by UL 1741 and IEEE 1547 standards to shut down during a grid outage. This is called "anti-islanding protection." It prevents your solar system from feeding electricity into downed power lines, which could electrocute utility workers repairing the grid. Without a battery or special islanding inverter, your solar system cannot operate independently of the grid.
How much does it cost to add a battery to my solar system?
In 2026, home battery systems typically cost $10,000-$16,000 installed, depending on the battery brand and capacity. An Enphase IQ 5P (5 kWh, essential loads) starts around $6,500. A Tesla Powerwall 3 (13.5 kWh, whole-home backup) runs $12,000-$14,500. Note: the federal residential tax credit (Section 25D) expired in 2025, so there is no federal credit on battery purchases. Some state programs like MA ConnectedSolutions and RI ConnectedSolutions offer $225-$275/kW in annual demand response revenue.
Can I add a battery to my existing solar system?
Yes. Most solar systems can be retrofitted with a battery. AC-coupled batteries like the Enphase IQ series and FranklinWH aPower2 work with any existing inverter. The Tesla Powerwall 3 includes its own inverter and can integrate with existing systems. Retrofit installation typically takes 1-2 days and costs $500-$1,500 more than a new-build installation due to additional electrical work.
What is the difference between whole-home and essential-load backup?
Essential-load backup powers only critical circuits: refrigerator, lights, Wi-Fi router, phone chargers, and possibly a sump pump. This requires a smaller (cheaper) battery and can run for 12-24+ hours. Whole-home backup powers everything in your home including HVAC, cooking appliances, and EV chargers. This requires a larger battery (or multiple batteries) and typically provides 6-12 hours of backup depending on usage. Whole-home systems cost 2-3x more but offer complete comfort during outages.
Do solar panels charge the battery during a power outage?
Yes, if your system is properly configured. During a grid outage, your solar panels can continue generating electricity and charging your battery through a process called "islanding." The battery inverter creates a local microgrid for your home, allowing the solar panels to operate independently. This means your battery can potentially provide indefinite backup during daylight hours, with stored energy carrying you through the night.
Get a Battery Backup Quote
Whether you are adding a battery to an existing system or starting fresh with solar + storage, we will design the right solution for your home.
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