Encapsulation doesn't have to suck

[andy]

The other night I had a revelation...the vacuum pump doesn't suck the air out of the encapsulant it just causes an enormous pushing force on the panel. The same effect can be achieved by standing on the panel(with qualifications). Consider a normal encapsulation set up; When the pump is switched on the encapsulant experiences a drop in pressure of what? 5 or 10 per cent? so the bubbles or air pockets will expand 5 or 10 per cent , but they won't be sucked out. This makes things very easy for EVA. ..... Dig up you're patio and get some concrete to cover an area a little bigger than the panel you want to make ,lay some wire (1mm iron ) zig zag on top of the concrete then put a sheet of glass on top. When the concrete sets and dries you have a solid flat surface with built in heating element, now put your panel on top , another sheet of glass, and on top of that the patio slabs for weight ; now connect the iron wire to a low voltage source and gently cook for a while . How many patio slabs do you need? does anyone what vacuum is normally used? I guess the average vacuum cleaner reduces air pressure by about 2% , to get the same effect that would be 200kg every square meter of panel........ What do you think?

[inetdog]

If you try to blow encapsulant, that really sucks

The other night I had a revelation...the vacuum pump doesn't suck the air out of the encapsulant it just causes an enormous pushing force on the panel. The same effect can be achieved by standing on the panel(with qualifications). Consider a normal encapsulation set up; When the pump is switched on the encapsulant experiences a drop in pressure of what? 5 or 10 per cent? so the bubbles or air pockets will expand 5 or 10 per cent , but they won't be sucked out. This makes things very easy for EVA. ..... Dig up you're patio and get some concrete to cover an area a little bigger than the panel you want to make ,lay some wire (1mm iron ) zig zag on top of the concrete then put a sheet of glass on top. When the concrete sets and dries you have a solid flat surface with built in heating element, now put your panel on top , another sheet of glass, and on top of that the patio slabs for weight ; now connect the iron wire to a low voltage source and gently cook for a while . How many patio slabs do you need? does anyone what vacuum is normally used? I guess the average vacuum cleaner reduces air pressure by about 2% , to get the same effect that would be 200kg every square meter of panel........ What do you think?

Well, first of all, you are thinking of a SUCTION pump, not a vacuum pump.
With a vacuum pump, the pressure is as close to zero as the pump can get it. The result is that the surfaces are pressed down/in with the force of the air pressure (14 pounds per square inch, which is a lot more than a typical patio slab.)
Second, the bubbles don't get a little bigger. They keep growing until one side of the bubble hits the edge of encapsulant and then the bubble bursts and all of the air is sucked out. (Idealized, in practice it is more complicated than that and you have to be careful about where you suck and what channels are provided for the vacuum initially.)

All you would be doing is making the bubbles small but keeping them in place, and when you took the patio slabs off the pressure would try to crack the encapsulant.

[Sunking]

Your idea will not work. Under a vaccum pressure is applied in every direction, not just sandwiched between two weights. As Inetdog points out a manufacture uses suction pump which goes to almost 0 air pressue, and they also heat it up which expands the air and drops the pressure even lower much like you do with a hot water canning procedure. They also pressurize the chamber to 3 atmospheres which in effect applies 60 psi under high heat. 60 PSI over 1 square foot is 4.5 tons of pressure or more than enough to lift a loaded 2 ton truck off the ground.

There is absolutely no way a DIY can duplicate what the manufacture can do.

[inetdog]

There is absolutely no way a DIY can duplicate what the manufacture can do.

And in your case, Andy, there is not even a way in which you could duplicate what a careful DIY with a vacuum pump could do.

[Sunking]

And in your case, there is not even a way in which you could duplicate what a careful DIY with a vacuum pump could do.

Yoy wanna bet. I can blow smoke as good as anyone.

[inetdog]

Yoy wanna bet. I can blow smoke as good as anyone.

I was addressing that to Andy, but using your quote (Sorry, I will fix that). I have a pretty good idea of what you could do when in McGyver mode, but you would not tell anyone here how to do that.

Also, before blowing smoke, you have to first suck it up, I think.

[andy]

Well, first of all, you are thinking of a SUCTION pump, not a vacuum pump.
With a vacuum pump, the pressure is as close to zero as the pump can get it. The result is that the surfaces are pressed down/in with the force of the air pressure (14 pounds per square inch, which is a lot more than a typical patio slab.)
Second, the bubbles don't get a little bigger. They keep growing until one side of the bubble hits the edge of encapsulant and then the bubble bursts and all of the air is sucked out. (Idealized, in practice it is more complicated than that and you have to be careful about where you suck and what channels are provided for the vacuum initially.)

All you would be doing is making the bubbles small but keeping them in place, and when you took the patio slabs off the pressure would try to crack the encapsulant.

I've been educated by youtube where everybody seems to use their mums vacuum cleaner and get great results. also check out this guy!! :- http://www.mainesolar.org/EVA.pdf I was really thinking of using it with EVA which seems better in every way , I guess the reason EVA is sold in a fluffy or spongy form and not a dense film is to allow air to air to seep out as it melts, I think were all being ripped off by these encapsulant sellers . Anyway I'm building a prototype, will keep this thread informed

[andy]

Your idea will not work. Under a vaccum pressure is applied in every direction, not just sandwiched between two weights. As Inetdog points out a manufacture uses suction pump which goes to almost 0 air pressue, and they also heat it up which expands the air and drops the pressure even lower much like you do with a hot water canning procedure. They also pressurize the chamber to 3 atmospheres which in effect applies 60 psi under high heat. 60 PSI over 1 square foot is 4.5 tons of pressure or more than enough to lift a loaded 2 ton truck off the ground.

There is absolutely no way a DIY can duplicate what the manufacture can do.

Many on you tube use a vacuum cleaner to suck out the air around the edge causing the face and back of the panel to be pushed together and heat with a hot air gun!! the results seem very good also check out http://www.mainesolar.org/EVA.pdf the photo of the little panel with 4 cells using EVA looks perfect. I'm not sure what the professionals are doing , aren't they putting the whole panel in a hot vacuum chamber ? in that case will be no pushing of the opposite faces together , can you explain whats going on with pressurizing to 3 atms , if the whole panel is in the chamber then there shouldn't be any pushing together of front and back , should there?

[russ]

Just be aware that maybe as much as 99.5% of what you see on youtube is pure BS & blather. Youtube draws the type that like to show off - act like they have an idea of what they are up to even if they have never seen something before.

[Sunking]

Many on you tube use a vacuum cleaner to suck out the air around the edge causing the face and back of the panel to be pushed together and heat with a hot air gun!! the results seem very good also check out http://www.mainesolar.org/EVA.pdf the photo of the little panel with 4 cells using EVA looks perfect.

Like PT Barnum said: There is a sucker born every minute.

I'm not sure what the professionals are doing , aren't they putting the whole panel in a hot vacuum chamber ? in that case will be no pushing of the opposite faces together , can you explain whats going on with pressurizing to 3 atms , if the whole panel is in the chamber then there shouldn't be any pushing together of front and back , should there?

Manufactures use a vacuum pump, not a vacuum cleaner. Huge difference.

Atmosphere Unit is an international standard of air pressure at sea level of approx 14.7 psi, so 3 Atmospheres is approx 44.1 psi. So when you use a vacuum pump which removes all down to 0 psi, then add 3 atmospheres of pressure outside the vacuum area the effective pressure differential is roughly 58.8 psi. The best vacuum cleaners out there can only lower the pressure about 20% or just less than 3 psi at sea level. You cannot even remotely duplicate what a manufactures do.

[fingolfin]

Atmosphere Unit is an international standard of air pressure at sea level of approx 14.7 psi, so 3 Atmospheres is approx 44.1 psi. So when you use a vacuum pump which removes all down to 0 psi, then add 3 atmospheres of pressure outside the vacuum area the effective pressure differential is roughly 58.8 psi. The best vacuum cleaners out there can only lower the pressure about 20% or just less than 3 psi at sea level. You cannot even remotely duplicate what a manufactures do.

So that begs the question if one were to roll their own machine to encapsulate solar panels, would it produce a similar result to raise the pressure on the container to 4atm, while forgetting about the vacuum entirely and having the internals of the solar panel vent to the outer atmosphere?
This would maintain the 3atm differential between the pressurized container and the inside of the to-be-laminated solar panel, while dropping the requirement for a vacuum pump.
This is advantageous because, in general, a vacuum pump better than that of the household vacuum cleaner is less likely to be lying around at home than something that can bring pressure up to 60psi (air compressor, bike pump, etc.)

That said, what seems to be the big drawback is that a container which can contain 60psi, big enough for a solar panel, and able to hold whatever kind of heating element one would be using would probably be expensive.

[inetdog]

So that begs the question if one were to roll their own machine to encapsulate solar panels, would it produce a similar result to raise the pressure on the container to 4atm, while forgetting about the vacuum entirely and having the internals of the solar panel vent to the outer atmosphere?

Quick answer: NO.
It could put the same amount of pressure on the surface of the panel, but it would leave air dissolved in the encapsulant or present as air bubbles which will try to expand when the pressure is released. A good vacuum pump will result in almost no air remaining and any bubbles would try to shrink when the vacuum is released.

[fingolfin]

Quick answer: NO.
It could put the same amount of pressure on the surface of the panel, but it would leave air dissolved in the encapsulant or present as air bubbles which will try to expand when the pressure is released. A good vacuum pump will result in almost no air remaining and any bubbles would try to shrink when the vacuum is released.

Very interesting. I figured it wouldn't be that easy. However leaving air dissolved in the encapsulant isn't too much of a bad thing, unless it changes an optical property of the encapsulant, or it condences back into gas after the pressure is removed from the solar panel. I realize that there is a reason the professionals do what they do. I just like bouncing ideas around.

[inetdog]

Very interesting. I figured it wouldn't be that easy. However leaving air dissolved in the encapsulant isn't too much of a bad thing, unless it changes an optical property of the encapsulant, or it condences back into gas after the pressure is removed from the solar panel. I realize that there is a reason the professionals do what they do. I just like bouncing ideas around.

Keep on bouncing, just remember to duck if they bounce back too hard.
Moisture in the encapsulant is far more of a concern than just air, as it can lead to damage to the cells or wiring eventually. The combination of vacuum and heat deals with that too. Pressure and heat will not necessarily do as well.

[fingolfin]

Keep on bouncing, just remember to duck if they bounce back too hard.
Moisture in the encapsulant is far more of a concern than just air, as it can lead to damage to the cells or wiring eventually. The combination of vacuum and heat deals with that too. Pressure and heat will not necessarily do as well.

Interesting. I get it now. You need to pull out all the air you can because with it comes moisture.
How about this as an alternative: You need a vacuum on the panel, you need pressure outside the panel, and you need heat somewhere in the mix.
Perhaps a sealed chamber, with a vacuum pulling on the panel. Outside of the panel, but inside the chamber is heated air. The ideal gas law will help a little, in that heating up a gas while maintaining volume and amount of gas will raise the pressure. However from the back-of-the-envelope calculations I ran, it seems that bringing the temperature from 20C to 200C, and starting at 1atm, would only raise the pressure to 1.5atm, so you'd definitely need to pump in more.
I suppose that's what the professional encapsulating machines do in a nutshell?