Solar Decay

The solar panels have been taking longer each morning to come on. Until one day it was noon and they were still not on. Grabbing the manual, I flip to the troubleshooting section. There is the description of this exact problem. Great. Scanning over to the solutions column, there are two possible solutions listed.
1) If it is a new install one of panels maybe wired in backwards
2) It maybe hazy or cloudy

It was not a new install and it was a bright sunny day. hmmm.

From the ground I sprayed the panels with the hose to see a layer of pollen blow off. It had not rained in over a week and the trees in our neighborhood have been dispersing allergens. So it was time to get out the ladder and head up there. In addition to the pollen there were a couple bird droppings. It all came off easily. Here is a picture of me on the roof.

Seems that they need to add another possible cause and solution to that user's guide.