Do Solar Panels Work During a Power Outage?
- If your home is connected to the grid, a traditional home solar system will not protect you from power outages.
- When grid power goes out, the solar array shuts off so that it doesn’t feed live electricity into the grid, which would be hazardous to workers who repair the power lines during an outage.
- If you want backup power to protect against outages, you’ll need to add energy storage to supply power when the grid goes down.
When folks call us up for the first time, we like to ask them why they are interested in going solar. One common answer we hear: “I need a way to keep the lights on during power outages.”
These people are often surprised to learn that grid-tied solar systems do not provide power when the grid is down—at least not by default.
In this article, we’ll explain why that’s the case, and go over the steps you can take to supply backup power to your home.
Why Grid-Tie Solar Systems Don’t Work During a Power Outage
The common assumption is that homes that run on solar should be immune to power outages, because solar panels generate power independently from the grid.
But that’s not the case. Here’s why.
Panels create electricity, but that’s just one half of the equation. You also need a place to store that electricity so it can be used later. Without storage, any energy your panels produce would be lost immediately.
Thankfully, solar owners are allowed to connect their system to the public utility grid through an agreement known as net metering. The energy gets sent into the grid, and the utility credits you for anything you produce. You then use those credits to draw electricity from the grid, which allows you to power your appliances at any time.
This agreement is tremendously helpful to the homeowner, as otherwise they would have to spend (tens of) thousands of dollars on batteries to store the energy produced by their panels locally.
The drawback is that your system is still hooked up to the grid, which means it is still susceptible to outages.
When utility power suffers a service interruption, the grid is shut down to prevent the risk of shock to utility workers who need to repair the power lines in order to restore service.
That means your solar system—which both feeds into and draws from the grid—needs to be shut off as well, so it doesn’t feed live electricity into the power lines while workers make repairs.
That’s the long and short of it. While your solar panels generate their own electricity, it is still stored in the utility grid, which means you are still vulnerable to power outages like anyone else.
When an outage occurs, your grid-tie solar system shuts down as a safety precaution, leaving you without power.
Is Backup Power Worth It?
The majority of our grid-tied customers don’t add backup power to their systems for a very simple reason: it’s expensive.
Backup power packages cost several thousand dollars, and in many places, power outages are rare enough that it doesn’t make any sense to add backup power. Most people simply buy candles or a flashlight and wait it out.
But that’s not to dissuade people who really need it.
If you live in a place with an unreliable power grid, or a harsh climate where winter storms can knock out grid power for extended periods of time, backup power starts to look a lot more appealing.
It can also make sense if you need to keep an essential appliance online at all times, like a well pump or a piece of critical medical equipment.
And in our home state of California, many customers are retrofitting existing systems with battery backup after PG&E announced scheduled blackouts to stabilize a power grid that was impacted by one of the worst wildfire seasons in history. With blackouts looming, roughly 20% of new systems deployed in California are equipped with backup power.
If power outages are uncommon where you live, it doesn’t make much sense to include a battery bank with your grid-tied system. But under the right circumstances, the peace of mind is well worth the investment.
The Solution: Solar with Storage
Both options have their pros and cons.
Pros of Battery Backup
- Uninterrupted backup power: takes over immediately when the grid goes down, keeping critical loads running
- Quiet operation
- Little to no maintenance costs (does not need to be re-fueled, etc.)
Cons of Battery Backup
- Expensive up front
- Typically sized to only back up essential appliances, due to the premium price on storage capacity
Pros of Generator Backup
- More cost-effective up front
- Typically sized to back up your entire home
Cons of Generator Backup
- Needs to be re-fueled
- Noisy while operating
- Requires maintenance
- Does not provide uninterrupted backup – takes a few minutes to switch on and power up