how to clear solar panels

A clean solar panel is a happy solar panel. (But, what’s the cost of happiness?)

One of the beauties of solar panels is their simplicity: They’re static, energy generation systems ... No moving parts, content as a sloth on your roof. Like sloths, they get dirty.

It rained -- barely -- last week. Not enough to even flinch the drought, but a decent amount of wet stuff to clean solar panels. Rain is like exercise for solar panels: Painful during (our production drops because of the clouds!), but fruitful thereafter (we're clean and powerful!).

The sole redeeming residue of climate change/weird weather/drastic drought is that solar systems are generating more energy than anticipated. For example, Repower homeowners' systems over the past two years are pumping out 6-15% more electricity than we had modeled. Little moisture in the ground (read: no fog), fewer clouds, more sunshine. A great potion for solar.

As rains diminish, should I clean (my solar panels) of should I chill? Stock answer for Yolo County homeowners: Clean them -- simply spray with a low-pressure nozzle; no soap or brushes are necessary -- three or four times a year, commencing a month after the last rains. There’s a lot of dirt in the air of our agricultural community. But, upon further review ...

... A 2013 UC San Diego study revealed it's not cost-effective -- and this was pre-drought, pre-water rate hikes -- to clean your solar panels. Synopsis:

Researchers found panels that hadn’t been cleaned, or rained on, for 145 days during a summer drought in California, lost only 7.4 percent of their efficiency. Overall, for a typical residential solar system of 5 kilowatts, washing panels halfway through the summer would translate into a mere $20 gain in electricity production until the summer drought ends—in about 2 ½ months.

Let them rest like a sloth? Perhaps. Sloths are quite happy in the sun.

P.S. - If/when you clean your solar panels, here are a few tips:

- DO NOT use high pressure sprayers as they can damage the seals around the frame. 

- Wash the panels in the morning to reduce drastic temperature changes. 

- Do not scrub the panels with any harsh materials. 

- If a brush is needed, make sure it has soft bristles. 

- If you notice rapid dirt build up—or bird droppings—then more frequent cleanings are warranted.