Why squirrels go nuts over solar panels – and how you can stop them

Compared to many of the problems that rooftop solar owners face – including utility companies trying to take away net metering or applying exorbitant fixed charges – the prospect of squirrels (and other critters) nesting under your solar array might seem a minor concern. But it can’t be denied that the rodents can do considerable damage with their teeth to the wiring that connects solar panels. The problem is compounded by the fact that the presence of the animals is often difficult to detect and even more difficult to eliminate. And why do the critters like to gnaw at solar wiring, anyway?

“It may be, essentially, force of habit that drives animals to chew on wiring,” said Keith Winston, Mechanical & Plumbing Engineering Supervisor at the Department of Consumer and Regulatory Affairs (DCRA) in Washington, D.C. “It looks like the twigs, worms and leaves that they otherwise ‘enjoy’ chewing on, and PV wiring has particularly thick insulation, giving it a particularly satisfying ‘mouthfeel,’ much like a refreshing stick of gum… also, many animals have habits of chewing or clawing ingrained in order to control overgrowth of teeth or claws.”

Winston said that the only good way to make sure that squirrels have not set up residence under your solar panels is by arranging periodic visual inspections.

“If you wait until you see the effects [of the squirrels] in system functioning… you have a problem,” he said. However, he cautions that the observation that “squirrels are there” isn’t the same as to say “squirrels are a problem.” He notes that it’s relatively rare, in his experience, for squirrels to nest under solar panels (though birds have also sometimes been known to do so).

Winston suggests that the best way to deal with a potential squirrel problem is prevention. Make sure the installer is diligent about attaching the connecting wires tightly to the modules and rails and doesn’t delay in transitioning into conduit (that is, Electrical Metal Tubing (EMT)) through a junction box.

Another way to prevent the squirrel problem from manifesting itself in the first place is to place screening around the modules, though Winston cautions that this may itself cause other problems, such as fallen leaves getting caught in the metal.

If you have not done the recommended preventive measures and you find a nest under your solar array, you should definitely try to remove it.

Winston polled the Solar United Neighbors’ D.C. listserv to find out what solar owners thought of this problem. The results indicated that only a minority, about 10 percent, identified squirrels as an issue, but those that did tended to regard them as a major problem. “Squirrels have built nests under a panel and gnawed wiring such that we have had to replace a single panel on two different occasions,” said one respondent. However, another indicated that though “nasty squirrels” on the property were a problem, they didn’t do damage to the solar wiring.

Those who harbor tender feelings towards even solar wiring-loving rodents should take heart: Winston doesn’t recommend destroying the animals.

“Killing [them] won’t get you anywhere, I believe. Unless you’re willing to do it over and over. It’s a poor choice.”