What Happens to Solar When the Power Goes Out?

When you're first looking into solar energy for your home, you may have many motivations, from saving money to being more environmentally responsible. Whatever your goal, the prospect of having an alternative energy source during grid outages is compelling to just about everyone.

It's easy to assume that as long as the sun is shining, your home will have power regardless of grid status. Unfortunately, it's not that simple. So what really happens when the grid goes down? Let's look a bit deeper. 

Unless you have a fully off-grid system and your house is completely disconnected from the grid, your solar panels not operate during grid outages. The reasons for this are both technical and regulatory. We'll take a closer look at both scenarios below, as well as explore how batteries can provide reliable backup power even if your home is still tied to the utility grid.  

Technical Reasons

As long as the sun is shining overhead, solar panels generate power regardless of how much electricity your home is actually consuming. In a grid connected system, excess solar power is sent back into the grid for a credit, and any additional power you need beyond what your panels are producing is pulled from the grid. It’s a constant push/pull between the two depending on the time of day and how much energy your home is consuming at any given time.

The energy produced from your solar panels reduce the amount of energy you need to purchase, but their production changes as the sun moves across the sky, clouds roll in, or night falls. Since your appliances require constant and predictable energy, the grid-solar interconnect creates a leveled power delivery throughout the day and night and from season to season.

Regulatory Reasons

Safety regulations are the second big reason that panels will not power your home when the grid is down. During power outages, repair crews could be jeopardized if there is a local power generator (like a solar array) leaking power back into the grid lines. For this reason, utility rules mandate that solar arrays must automatically shut down during outages. Solar systems have devices that sense whether power is coming across the grid, and when that’s disrupted, the local solar array is automatically shut down for safety. So even if the sun is still shining during an outage, the component that converts the energy into usable electricity for your house is turned off.

Solar Battery Backup Configurations

The only way to avoid a grid outage disasters is by completely disconnecting from the grid by installing a fully self-contained power generating solution for your home. An off-grid system generally includes solar panels, numerous batteries, generators, and other ancillary devices that all work together to provide 24/7 power regardless of weather conditions or seasonal demand. Going entirely off-grid also requires behavioral/lifestyle changes, not to mention significant upfront financial investment.

With all that said, a simple battery addition can deliver some peace-of-mind by providing just enough backup power to keep your most valuable assets safe for a period of time without the financial burden of a complete off-grid approach.

In general, there are two battery backup configurations: whole-home backup and critical loads backup. With a whole-home backup system, you can add just enough batteries to offset the most expensive on-peak utility hours, or add more to keep your house operational during an extended power outage. These types of systems are highly customized and unique to each family and utility rate plan.

Much simpler than a whole-home system, a battery backup system will run your most critical loads – or a designated room – during a grid failure when your solar panels aren't producing. Batteries are charged by your panels during the day for use during the night. This process repeats until grid power is restored. This is the more popular option since it generally requires fewer batteries overall.