Trade wars and shrinking tax credits aren't the only threat to solar power. Small critters can wreak havoc as well – something a California system learned the hard way.

A bird, or perhaps multiple birds, ignited a fire on June 5 at the California Valley Solar Ranch, knocking out 84% of generating capacity and scorching 1,200 acres. Clearway Energy Inc., whose subsidiary owns the ranch, blamed the blaze on an "avian incident" that damaged distribution poles and cables. It didn't elaborate how.

Animals have long been a menace on power grids. But such incidents at big solar power plants are rare, said Jenny Chase, a solar analyst at BloombergNEF. Residential solar panels are likely more vulnerable than big plants due to the variety in plant design and less oversight, she said.

Squirrels once ate through the microinverters on residential solar panels at a home in Quincy, Massachusetts, causing the system's electrical production to plunge. The homeowner told the Boston Globe that 17 of her 27 panels were ruined, resulting in thousands of dollars of damage.

There is business opportunity in this space. Jay Welsh, who runs the solar panel maintenance company Solar Maid, said in an interview that 80% of his business comes from pest removal. The most common issue animals cause is water damage, stemming from things such as holes in roofs and nests redirecting rainwater from gutters.

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