Are your solar panels clean enough? (1 Viewer)

[e9999]

So today I was playing with a solar panel and some batteries and inverter in preparation for a forthcoming power outage.
I had a 100W panel producing about 50W around solar noon ( cuz almost Fall and at not the best tilt).
The panel looked pretty clean really (I had sprayed it a few days ago), but there were a few dirt spots on it. Maybe a dozen, like 1/8" across. That bugged me (semi OCD or just normal OCDIY?) so I took a bit of water (used a few cups maybe) and a rag and cleaned the panel. I'll readily admit that if it were not for those ugly spots I would not have cleaned it.
To my pleasant surprise, the output immediately jumped to about 55W or about 10% more.
I don't think it was the spots that did it, more likely just a thin uniform layer of dirt -but, again, barely visible at that.
Good reminder for me to keep a closer eye on my panels.

Sooo, want a bit more free power or are you struggling with marginal production? Maybe your panel is also not quite as clean as it could be...

 

[spressomon]

I have been continually surprised how little difference there is between typically dusty panels versus freshly cleaned.

 

[e9999]

I had always assumed that if you could see the cells well enough under the glass that there should be relatively little loss. But I don't recall checking the actual numbers immediately before and after a cleaning. So I was surprised that the difference was that much. But this is anecdotal, not a real study, of course. Maybe it was a fluke. Maybe it was dirtier than it looked. Anyway, if I'm ever short of power, I will make sure to clean the glass, even if it gets me only a few %, it's easy enough to do for portable panels. This was the case for me today, I was trying to maximize the output because I was struggling to charge some batteries.

added: I did a bit of googling and the numbers on loss are all over the place, ranging from essentially nothing to surprisingly high (well over 10% and even seen 50% mentioned). Obviously it is a function of how dirty the panel get, which varies a lot by location and level of neglect, but the type of soiling matters a lot as well, apparently.