“We found that cleaning these panels is the #1 way to maximize the energy they produce,” the blog says.

It’s a different story in the Northeast where weather dynamics are markedly different.

“Snow cover is an issue. I could just not worry about it, but then I’d lose most of my output until it melted. In a winter like last year, it can be pain. I was out there 10 times,” says West Newbury, Mass. resident Rick Parker with his 3.6 kilowatt home installation. His cleaning tool is a car windshield brush attached to a long handle.

The only other time he cleans his panels is hosing them down to remove pollen in spring and early summer. They are angled at 35.5 degrees, face south and sit on a separate platform behind his garage.

“Otherwise, they clean themselves on their own accord in spring, summer and fall. I rub my fingers across them to see if there is [visually] undetectable grit and they come off clean,” he says.

Parker’s installation will be exactly two years old two days from now and has met his expectations. However, output in the second year is down eight per cent from the first. He suspects the culprit is weather, not panel degradation.

“This has been a very rainy and cloudy year.” The panels have cut his electric bill by 70-75 per cent.