Dessicant is almost always installed in the frames of double pane windows. The aluminum box around the outside has little holes toward the inside space which let the dessicant soak up the moisture but the little beads can't get in between the glass panes.
I've had four 100W, 24V panels out in the weather now for several months, only two showing in this picture.
Anyway, I had a moisture problem in one of them, so I just drilled a little hole in the top and bottom of the frame and the problem dissapeared. The other three are still sealed up with dessicant in the spacer, no moisture problems yet, though they seem easy to fix by just venting them.
Back when I did my project a couple of years ago, I tried to take what definitely worked and improve on it. So far, so good, though I only have four months of real-world testing out in the elements.
I know that I would not use plexiglass front and back until I found someone else who had used it with good results. Tempered glass and double-pane window channel has worked great for me so far and I based my design on someone else playing with these Evergreen seconds, back in the Ifred days, who used tempered glass in their design Sorry, can't remember who it at the monent. Maybe go searching stories back in the fall of 2004, that's when I was doing my reseach on how to build my panels.
