The following is based on my experience and may not have the same results on your location.
Two Coats of Sylgard 184
80 Watt panel with no back yet. See how transparent it is? Notice the air bubbles. Difficult to remove.
I've used EVA film and Sylgard 184 encapsulate.
EVA- $20/yard
For a 24" x 48" 60 watt panel- $30
is cheaper and a tad more work, but easier to position. Best to have some kind of kiln or oven to place the solar panel in. But, for a larger 24" x 48" panel, have to use a plug-in-the-wall hot air gun. If the EVA is not heated up hot enough it can unstick and peel off. I was told to put the mikly color down (but it's difficult to see the difference) Can't remember the temperature setting it was at, but it was around 120 degrees (med-high). Make sure to ask the EVA seller what the temperature range is... don't want to have a fire.
Best to try it out on a small panel to get the feel of it. If you like, I can send you a sample to play with.
Sylgard 184- Expensive $50 for a less than a quart.
For a 24" x 48" 60 watt panel- $100 - 200
The Sylgard 184 is the cats meow. It's main purpose is for exterior electrical encapsulation, keeps moisture out and is not vinger-based acidic (like clear caulking). Remains flexible in all types of weather and when poured in layers, it work really, really well. It's a 2 part solution which is mixed together and then poured over the back side of the cells. Has the constancy like corn syrup. Very hard to clean up. Through trial and error, pour a container on the glass, lay the strings face down and pour another container over the backside. One coat on the back in minimal for a large panel. In my West Coast climate, it took the panels 3 days to set. Made by Dow Corning
Note: I built my DIY solar panels about 3 years ago. It was a cheaper way to go at that time ($600/120watt panel in Canada). Sylgard is the best, but expensive for multiple large panels. But, all the DIY panels I have built, encapsulated in Slygard 184 are still working.
I'll try to post some pics on my blog for you to see. Feel free to contact me for pictures.
