This is a picture of my solar system. It's a bit grainy since it was taken late in a day, but there is something on it that is worth noting..
There is a line going across all the panels in the lower part. When I first saw it, I was somewhat puzzled. You can see it does not go parallel with the panel ties, but at the angle. That fact actually made me realize that it's a water level in the panels!
It just rained and got noticeably colder and the air was still very humid. There must be temperature difference of the surface of the panels between water and air field portions. Which resulted in different condensation amounts on the surface creating this effect. The pump was off at this point...
While pretty cool, I'm not too happy with water not draining completely. I think there are few factors that might contribute to that. The panels are basically water level and there is no much height drop. The vacuum breaker that I have seems to be pretty restrictive. There is Jandy check valve with a pretty strong flapper spring. The tubes in the panels are very thin, but probably still too big for any capillary action
I think come winterization time, I will need to blow the panels a tad to make sure they are empty..