sealing cells

[careful]

To start with the panel is already constructed and I would like to seal the cells to prevent premature aging. All the research I have seen state that the EVA sheet is hard for DIY to apply so I decided to use optically clear silicon namely RTV-615 . I did not realize that this product was hard to locate and when I did it was very costly over 700 dollar a gallon. This is totally unacceptable so I am scrapping this idea.

Question.: Does any one know of an efficient sealing material or encapsulate to seal solar cells or any other method not mentioned ??

Careful

[Mike90250]

You've discovered the bane of DIY panels, you can't seal them. The RTV would not have worked anyway, while it will seal against bulk water (rain) it does not seal against water vapor, which will eventually intrude, and begin to fog and condense on the inner side of the glass.

[philpaine]

Encapsulation

I would like to know more about encapsulation.

Does encapsulation really make a difference?

Also, I have read about 2 mthods of encapsulating solar cells to prevent contamination by moisture:

1. Encapsulation using clear film
2. Encapsulation by painting them with a special silicon liquid (I think it wa optical silicone)

Any preference regarding which method?

Thanks Phil

[ucfchuck]

sealing

i have found through a few places the most common commercial method is sealing with an eva and tpt layer, on the higher end stuff its an eva clear front layer and a tpt backing layer, though you can just go with the tpt on back or even just the eva on back, the tpt is meant to be a little more weather resistant but i think they will both last over 15 years as long as the env is too extreme . i am in the midst of putting together my own system from scratch and im going to just put the tpt on back of the cells and seal it to the glass i figure ill drop in a little silicon desiccant bag thing on the back of each panel inside the plastic.

i picked up just over 5kw of 6"x6" cells for a little under $2k, about 90 sheets of 14x48 3/16ths tempered glass for about $900, and about 1mx20m of tpt for about $250. then theres a couple of tubes of silicone to seal the backing material around the edges and to attach to aluminum rails.

tpt -

http://cgi.ebay.com/Solar-Panel-Cells-TPT-Back-Sheet-Encapsulation-5-1m-/320700033138?pt=LH_DefaultDomain_0&hash=item4aab362872#ht_500wt_1156

[Alan]

"The RTV would not have worked anyway, while it will seal against bulk water (rain) it does not seal against water vapor, which will eventually intrude, and begin to fog and condense on the inner side of the glass. "

Never used that material, but I've used other silicone encapsulants and had no such issue. Besides you could say the same thing about every single commercailly made panel that uses hot melt glue, also known as EVA that doesn't have a tedlar backing (tedlar being a water proof plastic). Eva leaks water vapor too!

A more proactive statement would be for extra protection seal any cells with a water proof backing like commercial panels have on them.

[Alan]

misleading

"The RTV would not have worked anyway, while it will seal against bulk water (rain) it does not seal against water vapor, which will eventually intrude, and begin to fog and condense on the inner side of the glass. "

Never used that material, but I've used other silicone encapsulants and had no such issue. Besides you could say the same thing about every single commercailly made panel that uses hot melt glue, also known as EVA that doesn't have a tedlar backing (tedlar being a water proof plastic). Eva leaks water vapor too!

A more proactive statement for encourgaging diy panels would be for extra protection seal any cells with a water proof backing like commercial panels have on them.

[Mike90250]

"The RTV would not have worked anyway, while it will seal against bulk water (rain) it does not seal against water vapor, which will eventually intrude, and begin to fog and condense on the inner side of the glass. "

Never used that material, but I've used other silicone encapsulants and had no such issue. Besides you could say the same thing about every single commercailly made panel that uses hot melt glue, also known as EVA that doesn't have a tedlar backing (tedlar being a water proof plastic). Eva leaks water vapor too!

A more proactive statement would be for extra protection seal any cells with a water proof backing like commercial panels have on them.

You are assuming I'm wanting to be proactive for long term DIY panels

Small scale, experimenter / hobby size, I'm fine with, but I won't encourage folks to invest heavily in a panel doomed to fail after a year or 2, or be likely to arc and cause a fire.

[Alan]

Are their any statistics to back up the doomed to fail hypothesis and fire prediction? The few stories I've read about solar panel fires tend to be from commercially installed ones.

[russ]

You prove they work - over a 10 or 20 year period. Not one panel but say 1000.

Some DIY types can build things very nicely for sure. Can most? The answer is no.

Russ

[Alan]

I'm already happy with my results. Saying something will fail with no evidence is not science it is an opinion. Call me in 10 or 20 years and I'll let you know how it's going. Probably as well as it has been going for a while. The assembly of these panels is so basic it's not like they are going to suddenly fail. The lack of logic behind needing 1000 samples is so far off basic statistical analysis it shows a gross misunderstanding of the topic. So far off base that it is absurd. It's like saying I want to buy a car, but to prove it is safe you have to crash test 1000 vechicles just doing a few doesnt' prove it to me.

I'm not the one making far reaching claims about all DIY panels every made using literally hundreds if not thousands of different methods all over the world with many different types of materials.

[Mike90250]

Saying something will fail with no evidence is not science it is an opinion.

Actually everything fails. Eventually, even the sun will. That's science.
If you make a claim something will last 5 years, it's your job to back it up.

[Mike90250]

.... Besides you could say the same thing about every single commercailly made panel that uses hot melt glue, also known as EVA that doesn't have a tedlar backing (tedlar being a water proof plastic). Eva leaks water vapor too!
.......

Do you know of any commercial panels, that do not use tedlar or something like it, for sealing the backside ?? AFIK, all use a Glass, EVA, cells, EVA, Tedlar sandwich.

[Alan]

if that was true than why does dow manufacturer certain silicone solar encapsulants that are ONLY sold to solar panel manufacturers with mixing/metering capabilities? Obviously either Dow has given me misinformation or your statement is incorrect. I'm guessing the latter.

[Mike90250]

if that was true than why does dow manufacturer certain silicone solar encapsulants that are ONLY sold to solar panel manufacturers with mixing/metering capabilities? Obviously either Dow has given me misinformation or your statement is incorrect. I'm guessing the latter.

Model # of the mystery encapsulants ?

So I'm wrong, and there is a product I don't know about . (since I'm not a PV mfg, how could I know about it anyway. How do YOU know about it ? )

[Alan]

Call dow up and ask them about 6100. Their phone number is clearly listed on their web site. How I learned about it is a secret.

and that is not the only chemical used for solar panels, ,,,