EVA incapsulation questions

**Mike90250** · 09-01-2015, 02:30 PM

Originally posted by sss

hi
new member here ...
i'm in the process of making solar panels .
i was wondering , do i really need the eva film from both sides of the panels ?
can i put the eva on the back of the cells only , and the cells directly on glass , so the eva will stick to the glass when heated ?
this way i'll have the cells incapsulated between the eva and the glass , whats wrong with that ?

thanks for anyone that knows

If the cells are in the middle, how does the EVA on the backside, glue the cells to the front glass ? EVA was chosen specifically to glue cells to glass for both it's compliance and UV resistance. (compliance - to absorb the thermal expansion differences of glass and cells so the fragile cells don't crack)

**sss** · 09-02-2015, 03:30 AM

Originally posted by Mike90250

If the cells are in the middle, how does the EVA on the backside, glue the cells to the front glass ?

the same way front EVA glues to back EVA . they glue to each other in the space between each cell .
if i use only back EVA , the blank area around each cell is where the EVA is glued to the glass .
the cells wont be glued to the glass , only held against the glass .
i hope i'm making sense

**foo1bar** · 09-02-2015, 04:07 AM

Originally posted by sss

the same way front EVA glues to back EVA . they glue to each other in the space between each cell .
if i use only back EVA , the blank area around each cell is where the EVA is glued to the glass .
the cells wont be glued to the glass , only held against the glass .
i hope i'm making sense

I can picture what you're saying - that they would only be held to the glass - like using tape across the back of a piece of paper that's visible in a window.
There wouldn't be any direct adhesion to the glass.

While I can picture what you're saying - I can not tell you weather it's a good option or not.

I assume you've already read the threads pointing out how DIY panels aren't cost effective.
So this must be something you're doing just for fun.
So I'd say do some panels each way. Worst case you have a panel that delaminates because of insufficient adhesion of the wafers to the glass, and you can show on you-tube why that approach is a bad idea and get a bunch of views that way.

**inetdog** · 09-02-2015, 06:42 AM

The eva on the back may produce adhesion to the glass in the area between the cells, but that will leave two more surfaces with changes in index of refraction to cause reflection of the incoming sunlight. That could cost you as much as 8% in energy loss.
And it might leave the cells vulnerable to cracking unless the back plate is as rigid as the front glass.

**sss** · 09-02-2015, 11:39 AM

Originally posted by inetdog

The eva on the back may produce adhesion to the glass in the area between the cells, but that will leave two more surfaces with changes in index of refraction to cause reflection of the incoming sunlight. That could cost you as much as 8% in energy loss.
And it might leave the cells vulnerable to cracking unless the back plate is as rigid as the front glass.

i intend to use sunpower c60 cells which have no glass on top of the cells and are not reflective , do you think it will lower refraction compared to other commen cells ?

**inetdog** · 09-02-2015, 03:41 PM

Originally posted by sss

i intend to use sunpower c60 cells which have no glass on top of the cells and are not reflective , do you think it will lower refraction compared to other commen cells ?

I assume that "not reflective" means that they have an anti-reflection coating, since everything that is transparent is also reflective to some degree.
This will not have any effect on the reflection from the rear surface of the glass.
But when the encapsulant has an index of refraction close to that of the glass and the silicon there will not be any need for that anti-reflective coating.

**jkennedy** · 09-03-2015, 09:43 PM

What about just using eva, without the glass? Although it would be easy to do damage to, would it work?

I'm in a climate that doesn't change much in temperatures beyond 25-30C. Heavy rain is about the worst the panels would see.

Other reason is the expense of glass, while I could bring EVA material on a plane fairly cheaply.

**Mike90250** · 09-07-2015, 02:10 AM

If you have no glass, what makes your panels rigid enough to not crack the cells ?

**sss** · 09-07-2015, 03:47 AM

eva is very tacky , no glass will make all kind of dirt to stick to it .

**jkennedy** · 09-07-2015, 12:03 PM

Originally posted by sss

eva is very tacky , no glass will make all kind of dirt to stick to it .

That makes sense. Is there anything that could be applied over it to create a barrier, without getting into glass? I was thinking of something like a unisolar panel with a slightly more flexible coating, maybe some kind of thin plastic or laminate that could cover the eva? like the glass normally would to absorb the tacky texture of it?

I know it would be very fragile, but with the temperate climate I'm dealing with, it should be decently safe from anything hitting it.

EVA incapsulation questions

EVA incapsulation questions

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