No, not bad language, just dirt. I've read that output can decline on the order of 15-20% with soiling. I suspect most homeowners don't think about it -- out of sight, out of mind. Perhaps companies that offer leasing arrangements are incentivized to come around and clean periodically (if payments are linked to actual output), but what about user-owned systems? Anyone ever looked into partnering with window-washing companies to promote this service? I just asked ours and they only have two customers who ask them to wash their solar panels.
This is a great idea. I clicked on your discussion because it made me remember that I forgot to get up on the roof early enough (before the heat of the day) and wash down our solar panels! I believe you hit the nail on the head when you said out of sight, out of mind, this is certainly my issue. After working 50 hours a week and coming home only to work on several other projects, I forget to put this on my list, come Monday, oops...I didn't clean them again. I clearly know the consequences of declining output....and still it's not on the top of my list. Thanks for the reminder. As for folks that aren't in our industry I believe it's like all else, education is king and if educated on energy topics it would get folks moving on otherwise "back burner" projects.