Argon in a Photovoltaic Panel (Not Solar Heater)

A desiccant should be used. It will remove all the water from the seal atmosphere of your panel. I would recommend glass. Its clarity is better and is more abrasion resistant. Silicone will seal it. You would get better life out of butyl rubber or a polysufide. Also I question the aluminum back. If it's going to get hot then the life of the seal will be shorten. Expansion and contraction will cause it to tear. Would not drill though, set spacer in about 1/4 inch and fill the edge with sealant. A good sealant and screwing it will be unnecessary.

Thanks! Any desiccant in particular (silica gel, CaCl, etc)?

WR Grace 3A/13X IG Grade

Plexy or acryl windows is not a good idea. The extension coefficient difference with Alu is too high to seal with a decent silicone caulk -anykind. I am talking about mm/m. Hardened glass is a lot better. Professional builders use liquid hardening seal, like in multilayer glass to fill gaps between the glass and cells. So there is no room for condensation. The cooler you can keep your panel, the better it will produce.

I've searched on the net, but I can't find anything. Do you have a brand/trade name for such a seal?

Why argon? Why not just dry nitrogen, carbon dioxide or plain air.

We've got a tank of it here in the shop, and no one's using it! LOL

There is no free lunch. Desiccants will extend the useful life of unit. However a desiccant is like a sponge; eventually it becomes saturated and stops working. So, the design must include sufficient quantity of desiccant to obtain satisfactory life (given actual water ingress rate), or the ingress rate must be reduced to obtain sufficient life. Purging the internal gas with dry gas will work, but is a maintenance concern. For a lesson on how experts maintain internal atmospheres see how they preserve the Declaration of Independence.

I am using EVA to bond to the glass.

http://en.wikipedia.org/wiki/Ethylene-vinyl_acetate

PET (aka Mylar) as backing.

http://en.wikipedia.org/wiki/Polyethylene_terephthalate

Removing the air pockets is the hardest part so far!

Are you gluing the mylar to whatever rigid/poly backboard you are using?

On the EVA, is there any Loctite product that works particularly well? Some of their products contain it. I've tried calling the company a few times, but can't reach a rep.

On the EVA, I use sticks of hot met glue. I have been using glass (1/8"), but We get large (2" to softball size) hail here occasionally so I am concerned I may see my whole system be turned into junk! Tempered glass adds a significant amount to the price. I don't know how to do an anti-reflection coatings yet.

The mylar is bonded with the EVA, but I am toying with the process, because I need to vacuum it down, but my current cells are so fragile I am afraid I'll crack them.

So I feed the EVA on as I lay on the mylar, melting it with a heat gun. It is awkward, sloppy, and too time consuming! I am going to try using enough EVA to cover the back of the cells. Next panel, I am going to melt enough to cove the back in a thin layer or heat the whole thing to let it level out Then apply the Mylar.

I"ve been using mosquito net and silicone II for my backing.

To purge, I installed two schrader valves. The HVAC teacher at our high school drew out air while pumping in the argon. I"ve had Nitrogen suggested by a fellow yesterday as being more effective, but that would be another purchase, and we're trying to use what we have already.

For your application, dry is all that counts. It makes a vanishingly small difference what the internal gas is. You just need to maintain close to equal pressure on both sides of the window and a low dew point inside. You can change the inside gas as the dew point increases, or you can continuously purge at a low flow rate.

I'd be using Clear Acrylic instead of plexi glass. Clear Acrylic is 25 times more impact resistant than glass and has the light transmission quality of the finest optical glass. After all, you want as much light as possible to get through to the solar cells. Just a thought for you to consider.