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In battle with squirrels, solar panels finally claim victory

After suffering a solar panel power outage due to squirrels with a taste for electrical cables, CNET's Martin LaMonica evens the score and learns his lesson.

The damage done: squirrels chewed cables connecting solar panels and cut the power.
Martin LaMonica/CNET

For the most part, solar panels can safely be ignored and simply keep turning your meter backwards. But thanks to some local squirrels, I realized the perils of not regularly monitoring solar panels' output.

These days, it's not difficult to view the electricity generated by solar photovoltaic panels online. And homeowners are increasingly choosing to lease panels, rather than buy them upfront. That means a solar installer or financing company will own the panels and they'll have a financial interest--in the form of renewable energy credits--to monitor rooftop panels' output.

When I had my PV panels installed four years ago, though, none of those leasing options were particularly easy. And a couple of squirrels made me pay for it.

I had often seen squirrels scampering around on my roof so I didn't think much of it when I noticed them on the solar panel side of the roof. But one day, I saw one of these critters run along the roof peak just above the solar panels and then dart underneath the panels. It's almost as if he was coming home from a busy day and was settling in for the night.

But I love chewing on cables! Martin LaMonica/CNET

Clearly, this called for immediate action. If this guy or girl made a nest underneath the panels, it could cause all sorts of problems. Perhaps they'd bite through the wiring underneath the panels and cause a short, or simply disconnect the entire operation.

I did nothing. Hey, life is busy and denial is a powerful thing. I rationalized that perhaps they wouldn't cause any problems, even if they were nesting. When I had some work done on my chimney, I asked the contractor to clean out under the panels and hoped for the best. Then months later, something finally forced my hand: data.

If my panels were wired up to the Internet, I could have easily seen whether the rodents on the roof were causing real trouble. I could compare weekly or monthly data across the seasons and see if there was a drop-off in production.

I do track monthly production but my primary view is simply looking at the inverter in the basement. An inverter is a box that takes the direct current from solar panels and converts it into household electrical alternating current. Because I've had the panels for a while, I generally have a good idea what power to expect. If it's sunny at midday in the summer, the panels will produce about 2,300 watts, etc.

A few times early in the winter, though, those real-time wattage numbers seemed awfully low. Then when I looked at the monthly data for December, I knew something was seriously wrong as it was well below the average for the previous years.

The solution
This realization set off a scramble to actually deal with the problem. Cutting down or severely cutting back the trees wasn't a long-term solution given how close they are to my house. And in fact, I had two problems: to repair the electrical problems and find a way to keep the squirrels from coming back.

One wildlife specialist who took a look said the nest was still there but the squirrels weren't causing any problems. Another didn't offer any practical advice and clearly wasn't interested. Finally, I found a solar installer in New York who had some experience with squirrel guards and solar who recommended installing a high-strength screen around the edge.

Luckily, I found an animal removal service professional who agreed that a screen was doable without screwing into the roof, which would risk leaks, or damaging the solar panels. The installers attached a heavy rigid screen by screwing it to the racking. In a couple places, they replaced an existing screw on a wind guard along the edge of the panels to attach the screen. So far, it seems to be doing the job and doesn't look out of place.

After some tests, my original installer quickly realized that one of the two strings of panels was disconnected. When he went onto the roof, he eventually discovered the root of the problem: chewed-off wires. Apparently, squirrels simply enjoy biting on the chewy insulation that wraps around the cables that connect the panels. It took a while, but replacing those cables got the panels back to full power.

Hopefully, this is the final battle I need to wage against rodents with regard to my solar panels. But the episode was an expensive reminder--costing well over $1,500--of how important it is to monitor panels. In addition to paying for the work, I lost a good amount of electricity production by being late to address the problem, none of which is helping the payback of the system.

The good news for people now considering solar PV is that online monitoring options are far cheaper and easier. Microinverterscan even report how each panel is performing individually.

Having somebody else, such as the installer, own the panels shifts that responsibility altogether, another reason why solar leases or power purchase agreements with solar installers are becoming more popular. Meanwhile, a glut of panels has caused a dramatic drop in prices over the last three years. And, as you now know, there are viable ways to avoid potential squirrel problems.

As for me and my squirrels, we're no longer at war. This morning, I tried to snap a photo of some resident squirrels for this article. I got the black one, but the gray one escaped my view as he leaped--onto the roof.