Epoxy for encapsulating cells (great DIY thread with photos!)

[DeltaFox 25]

I to have made a panel with the 6x6's but like you said they break very easy. I for some reason miss measured the glass and the frame so it left me with hardly any extra room. I have cell's overlapping the frame and no room in between. I guess I'll learn next time. I have decided to go with 5x5's . I can get them in grade "A" , so that will be what I'm going to use. I want to make several 72 cell panels.
It will be nice to see your pictures of what you have done.

[bladerunner]

Sylgard issues

Hello all,
I have been very busy making some panels for a friend in the Philippines, I used Sylgard to seal them because it seemed to be the most reliable method available.
I will post pictures eventually but wanted to share things I have learned that may help others avoid my mistakes.
I used 6X6 cells bought off e-bay that seem to work very well, just insanely fragile as most of you already know. One of the problems I have encountered is that when you are soldering the tab wire on the face of the cell, you MUST have a smooth finish to it, any bumps or spikes in the solder will hold the cell off the surface of the substrate (glass or acrylic or whatever) and cause a void or bubble. Also the bigger cells seem to warp as you solder them (I think this is due to heat being applied to one side of the cell) and I am not sure how to avoid that.
I first tried the method used on youtube with limited success, much of it probably my own fault (spikes in solder, curled edges, etc) too many voids.
I also read that you could speed the curing process by heating it. So I popped one in the oven, and it worked really fast (1/2 hr compared to 48+ hrs) DO NOT TRY THIS!!!!!! after I took them out, the cells buckled and cracked horribly! The voltage seems to be correct, but I have yet to try them for amperage output, am keeping fingers crossed. I am scared to try and flatten them back out, as long as they work I will probably leave them this way. Will post pics later, still busy making them.
The second method I have tried is to paint sylgard on the glass first, then put the cells on top, finishing with painting sylgard on the back, using weights to press the corners down into the sylgard seems to work well also (sockets, random bits of metal, lugnuts etc. I put bits of plastic under them to keep them from becoming glued down. A full sheet of plastic covering the whole back may be a better idea)
Gotta run for now, just wanted to share progress so far.

[DeltaFox 25]

I think they want you to buy more , like 7 of them ,. I heard of a guy trying to buy from them and he was oversea's and they said that sence he was they wanted him to buy 7 of them. but if you can call them maybe they can help you. I buy 3 at a time.

[Jockito]

Where do you buy your sylgard at?

I haven't bought it before, but i was thinking from ebay. Do you know if Superioressex posts internationally? that way i could buy 3 for less.

[DeltaFox 25]

I'd really like to work with EVA and Tedlar but I just don't have the rood or the money to make a vacuum table.get another piece of plywood and assemble them ontop of that just like you were going to put them on the glass and then all you have to do when you put the sylgard down on the glass is to slide the cell's off the plywood on to the glass where you want them

[Sandman57]

manual pour?

How do you guys handle a manual pour? My cells are not perfectly flat with a combination of slight concave and convex shapes. It seems that these curls would either trap air or require more encapsulent to cover them up.

I am lucky because I have access to a vacuum pump and autoclave. I have just ordered EVA sheets that I plan to use to encapsulate my cells in a vacuum bag. I will post some pictures to show the process.

[DeltaFox 25]

Why don't you get another piece of plywood and assemble them ontop of that just like you were going to put them on the glass and then all you have to do when you put the sylgard down on the glass is to slide the cell's off the plywood on to the glass where you want them. You might have to have someone help you but it will be a better panel. Two slygards should be enougth but with that large of an panel it might be better to use more.
I'm doing a 72 cell panel of 5x5's 32x62 and I'm going to use 2 sylgard for the bottom and 2 sylgard's fro the top.
Where do you buy your sylgard at?

[Jockito]

Oh ok. Thats interesting to know. I was thinking of doing it exactly how he was, but maybe i should think about it. It sounds like it would be difficult to handle the cells once all connected though if putting them down after the sylgard. for example, the solar panel im making is a 72 cell (4 columns x 18 rows), and soldering the bus wires together while the sylgard is wet sounds too tricky, which means i'd need to somehow hold the entire array of cells and place it on the sylgard...which i can't see how it would work.

I remember the youtube guy poured the sylgard so that only 3 edges of each cell had sylgard poured on it, allowing the sylgard to seep under without creating bubbles, but i guess if you tried it four times and it didnt work...

Also, do you think 2 Sylgards will be sufficient for a 72 cell panel? Im thinking of getting them off ebay, unless that superioressex website can send international? im from australia.

[DeltaFox 25]

I have made 4 panels the way the youtube guy made his and I have allways ended up with air pockets in it so now I;m going to put sylgard down first then cells then sylgard again.

[Jockito]

I have don that but with sylgard. I'm going to start a new way, First put sylgard on to the glass , then put the cells ( already tyed togeather and bussrar also) on top of the sylgard , then put more sylgard ontop of the cells. this way it will completly take any air out.

From what i inderstand of Sylgard, by pouring it over the cells it seeps underneath and all around cell, completely encapsulating it, this is what i saw done on a youtube video. Wouldnt that mean it is unnecessary to put Sylgard down first? The only thing to be mindful of that can happen is that air bubbles can get trapped if you dont pour it onto the cells right, but they can be "chased" out by moving or tapping the cells.

[Sandman57]

don't use epoxy

There are two issues with epoxy.

1. it is not flexable so any heating or contracting differences between the cells and epoxy will create strain on the cells.

2. Most epoxy is not UV resistant. In fact one year out in the sun and it will turn white or yellow and become brittle.

I wouldn't use it for encapsulation

[DeltaFox 25]

I have don that but with sylgard. I'm going to start a new way, First put sylgard on to the glass , then put the cells ( already tyed togeather and bussrar also) on top of the sylgard , then put more sylgard ontop of the cells. this way it will completly take any air out.

[jestronix]

If you use a glass with a frame then coat the back of cells back of whole panel with sealoflex would this work for encapulation? Or would the cells still be in some contact with moisture?

I have cells where I have siliconed the cells to the glass, then painted the back of the cells with an undercoat and an exterior waterproof stretching paint, they have done 4 months of solid tropical heat and rain, not one bit of visible moisture, but too early to call yet.

The air itself that was trapped in there will surely contain some moisture, enough to kill the cell? time will tell.

[BilljustBill]

I have also made a solar panel. Its a large panel 55 6x6 cells..putting out around 27V. Its about 36'w X 72"h

Used Sylgard to encaspulate..took 2 cans..I would like to see a cheaper encapsulant..

I still wanna put something else on the back side of cells..sylgard has them mostly covered..but still wanna add something else..A bit worried about heating of compounds to flex and break the cells...

Considered rubberized swimming pool paint..its cheap..but could not find white

..but kinda like this stuff better
What do you guys think about this stuff ???

http://garage-toys.com/pldippepr.html

I've seen that at the local Home Depot. I wonder how it rates against short and long term UV exposure?

Bill

[DeltaFox 25]

It sounds like it would work , I have never tryed it. i used sylgard on the front and the back.