Dirty Solar Panel

As I’ve pointed out in my other article, “Cleaning Solar Panels – Does it make much difference”, I discovered that it actually does make a difference… and sometimes a surprising amount of difference!

Well, last week I was looking at my data on my solar panels and I kept seeing this one panel consistently under-performing compared to the rest.

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I of course know that different panels have different efficiencies from the manufacturing process, but this one panel had never been a problem before.

So, for the last few days I’ve been meaning to go outside and take a look at the panel to see what I could find, and I saw the reason! You can see the darker areas at the top of the middle panel where the dirt is causing the panel to be less shiny.

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It turns out that this one panel isn’t as clean as the others.  I guess that when I cleaned my panels a few months ago, I didn’t do a very thorough job on this one panel. It’s obviously making a difference!

I exported some recent sample hourly data for the panels and found that this panel has been consistently at least -2.5% less efficient than all of it’s buddies. I also pulled up some pre-cleaning data and it looks like this panel, when clean, performs at about the average proficiency of all the other panels, which means it’s also -2.5% less efficient than what it would be if it were clean.