Copyright 2020 - The Energy Show, Barry Cinnamon

There are over a million homes with rooftop solar in the U.S. – out of about 100 million detached single family homes. So we are looking at market penetration of about 1%. There is a lot of growth potential for solar, storage and maintenance work.

Once people have a solar power system the first question they ask is “how do I read my electric bill?” The second question they ask is “how often should I clean my solar panels?”

Now reading your electric bill – that’s another show altogether given how complicated the bills are. But on today’s show we’ll mathematically and practically answer this second question –how often should I clean my solar panels.

We will base our recommendation on daily and annual performance analysis of systems before and after cleaning and also provide advice on how – and especially how not -- to clean solar panels.

To start, you might be wondering how the solar panels get dirty. They get dirty basically by wind-blown dust. Just like your car or your windows, the dust accumulates on the surface and builds up over time. And, if you are in a dusty area like a farm or near dirt roads, the accumulation may be worse. Pollen accumulation is another factor which typically happens in the spring. Some people talk about cleaning up after the birds, but bird debris is usually not a problem unless your name is Hitchcock and you live in Bodega Bay.

What happens when panels get dirty the accumulated dirt absorbs or reflects the photons that hit the solar panels and output begins to decline. The amount of output decline varies based on location and amount of soiling. Interestingly enough, it also depends on where on the panel the soiling happens.

So if you are like most solar power system owners and you have been wondering how often should I clean my solar panels, please listen to this week’s Energy Show as we walk through the performance implications of dirty solar panels and the best method for cleaning your system.