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.


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.


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.