DIY laminator for PV panels?

[amiklic1]

I plan to make some device similar to those fancy factory vacuum laminators, for PV panels production. In my country you need to pay about 500 US$ for 50W panel, and it seems it's good area to make some business, and also to be cheaper than others.

It costs me about 200 US$ to build 50W panel. Since now I built 4 of them and sold three for 350 each.

I plan to make laminator with 8mm copper plate inside, and with the lid that has some membrane. I don't know what type of membrane to use??

I order some EVA and TEDLAR sheet samples (they sent them free!!) to practice laminating proces. It doesn't look complicated, but I need some basics to learn. Has anyone seen some homemade stuff like that?

All answers are appreciated!

[ibdilbert]

I know this post is rather old, but I was curious as to find out if you made one or not?

I made one but still have some bugs to work out, I keep getting bubbles in between the EVA.

[oztules]

 ibdilbert

If your going to make a panel, then do it soundly. You already have the EVA and some backing material of some sort I figure... so this is how i did it....

1. an oven big enough to take your panel size (mine was 8feet x 4 feet)

2. A plastic bag big enough to envelope your panel (yes mine had to be bigger than 1meter X 2 meters... make your own from sheet plastic and a heat gun... I did)

3. A vacuum pump. Mine was a $125 unit from china. Will pull a near perfect vacuum for hours on end. Dual vane rotary.  A  5" 3 stage lamb bypass vac motor in series with another 5" 3 stage vac motor may do.... but they must be bypass types, or they will overheat and die pronto.... a proper vacuum pump will be cheaper and better though I suspect..... you ideally want to pull a near perfect vacuum, although I'm led to believe that this is not absolutely necessary, and pressure can be used for part of the process... I don't agree or see the need for this complication.

4. Bubbles are from poor vacuum.... simple. My panels have no bubbles at all.

5. Your oven needs only to get to about 100-120 degrees C while in vacuum mode, so decent size garbage bags will do if your panels are only 60 watters (my big one was 200w plus). The plastic will get soft, but not melt.

6. leave it for at least 40 minutes in vacuum mode around 100- 120 degrees. Cross linking is happening now........longer at cooler temps, faster if you can get the temp up without killing the bag.

7. If you want a  better eva to glass bond (yes please), you can now remove the plastic bag and the  vacuum, and heat it to 140 degrees for  five minutes or more... it will them stick like the proverbial to a blanket. If you can get heat proof bags, then it is better to keep a vacuum on it if you can (I could not get the plastic to hold it's form at that temp)

It is falling off a log simple, and I don't know why the yokels on youtube that pretend to make good cells persist in making short term cells, that cost more than making them properly, and clearly wont last the 25 year distance.

You don't need to build a fancy laminator... they are just not necessary, and don't provide any better environment than a simple wooden oven (with lots of insulation) and a oversize heat gun to heat it up, a vac pump and a plastic bag and rubber hose.

Just bring the cells, the EVA front and back, backing sheet and glass, and its done...


.............oztules

[ibdilbert]

Thanks for the GREAT reply!   I wish I had all these tips when I started!   

Placing the panel in a bag and pulling a full vacuum then heating it up seems a lot more simple than what I've been trying to do.   Any issues when pulling a full vacuum of cracking the cells?  Or can the cells handle that kind of pressure? 

[oztules]

The cells will see their surface area in sq inches x about 14..... so a 6x3 cell sees 18x14=250 odd pounds of pressure for each cell....

You know they are flimsy as all get out, but they will tolerate it very well if supported well.

If you tab them yourself.... make sure you keep the soldering as flat as flat. Any lumps left will put uneven pressure on the cell and break it,...... same with the backs... try for even.... even..... even. Then full vacuum of space will not hurt them.

You will need to use  porous material (linen sheets etc)on the back of your tedlar or whatever you are using as the backing sheet (over the back EVA) . This needs to be there to allow the vacuum to evenly cover the tedlar.... otherwise it will only be around the suction area.

Good vacuum means no bubbles.

DONT allow the suction hose to rest on the rear of the cells. make sure you have some porous material out the end of the matrix, and place the hose into that...... otherwise the hose will press unevenly on the back of that cell and break it.

Plastic bags seal well around rubber hoses with plastic wire ties.

I tried shade cloth as an open weave material on the back of the tedlar to help the vacuum spread evenly easily, but it seemed to shrink with the heat, and actually moved the cells....fine flywire will work and there are many other things to try.... but if you get a perfect seal, bed sheets will work... albeit a bit slower for the vacuum to spread. over the entire area.

Here is a test panel. It is normal glass (window), ....eva, ....cells, .....eva, .........tyvek (building wrap, teflon/aluminium Dupont stuff..... well..... I had it hanging around...)


That one was done in a normal black garbage bag (240 liter)

It is no big deal that the window glass is breakable, as the EVA makes it into laminated glass... you can crack it but not break it.... interesting side benefit.

I did this on purpose on another panel, and it does not break or fall apart, it just keeps on going perfectly well, the EVA holds it together just like a laminated windscreen ...... unlike broken tempered glass... it becomes useless..... and you can use windscreen repair resin to fill the crack line to stop any hint of moisture discolouring the crack line.... just like a windscreen.

Close up of a panel..... yes the crooked one is because I'm slob....


EVA is only about 7-10 dollars per meter.... why anyone would do it any other way than the solar cell manufacturers do, is beyond me. That slygard stuff is expensive compared to EVA.... and you still have to address the bubble problem.... any other way is tempory


.............oztules

[ibdilbert]

Very impressive!!!  And I never thought of using tyvek for a backing, tedlar seems to be expensive.  I'd be interesting to see what other people are using for the back sheet.

[ibdilbert]

This weekends attempt at making a no bubble panel with EVA was not so successful.  





I've been using broken cells and as you can see in the picture just placing them in between the eva petty haphazardly, but just wanting to see if I can do this w/out any bubbles before I try to do this with good cells.

It seems this time there are no bubbles on top of the cells, thats a change as I've been getting bubbles everywhere.   The current setup is as follows.

Vacuum Pump is a dual state rotary vane made by VIOT that pulls 29+ inches of vacuum, 5.5cfm.   I was able to confirm a leak free bag with the vacuum gauge.  The bag I made out of silicone sheets that I had left over from another project.    

For heat I have a large hotplate that I set the thermostat to 110c and also used a temperature probe on my multimeter to double check the temperature.

I used cotten sheets over the back side of the panel to allow for air/vacuum.  

The EVA is .5mm cross hashed on one side.

Layered like this...

Glass
EVA (smooth side towards glass)
Cells
EVA (smooth side towards Cells)
Tedlar

I pulled the vacuum before sitting it on the hotplate.   Any idea why I still got bubbles?  

[oztules]

As good an attempt as I have seen by anybody else on here by far.

You have a much bigger pump than I, but it does not go to an absolute  vacuum. I have heard that this is better.

I can however confirm very good results with less than stellar vacuum, and still no bubbles...... so it must be some thing else.

Your pump is 4 times bigger than mine, and so will mask tiny leaks much better than mine. Any leak no matter how small will scotch your vacuum, unless you find something very porous and flexible for the back sheet...... those bubbles were where they should not be. The vacuum pressure experted on that part of the EVA should have squeezed the life out of them.... but it didn't.

Conclusion..... use more bed sheets, fluffier ones, scotchbrites or anything else that will move your vacuum faster than any possible leak. If it leaks in the slightest, the sheets will not let the vacuume travel fast enough, and your gauge will show happy, (because you have big capacity), but there will be parts not under proper vacuum/pressure.

Those bubbles were in places that had less pressing power than you should have had. The tedlar and the sheets did not form into the small inter cell gaps etc... so we must have had poor pressure at those points.

If you had a near good vacuum, and NO leaks, this would have done it, as the vacuum would spread... slowly... but surely everywhere. A leak will only channel the vacuum over the easiest route/s..... those bubbles were out in the open..... should have been fair game.... has to be inconsistent vacuum.

 In theory you should hold it at 65C for 15 mins and then move the temp upwards slowly (I didn't, but mine heats slowly due to it's size ond relatively low power), but I still think leak.

Keep it up, good cells are only a leak away I fear. I know you confirmed no leaks, but all the things I have read, and tested myself point to leaks=bubbles.... nothing else (poor vacuum excluded, but yours should have been sufficient)...... alternatively, better porous material will sustain small leaks with less bubbles I think.


Well done. It's nice to see someone else doing this. We should get a few more folks doing it, and a better knowledge base will eventuate.



..................oztules

[oztules]

For some additional information ( in case this is being read by others thinking of having a go), heating profiles for laminated windscreens look something like this

General heating profiles:

1. Hold a vacuum at room temp for 15 mns

2. take it to 60C for 20 mins

3. Take it to 130C for 40 mins

Vacuum on all the time.

Low temperature curing looks like this:

1. Hold vacuum for 15 mins at room temperature

2. take it to 60C for 20 mins

3. Increase to 80 - 90C for 70-80 mins

This last one allows you to use a feeble home made oven, and garbage bags or equivalent to tolerate the low (less than boiling water) temperature.

If they can do it for windows, then solar cells are a cinch...... and they are too.


........oztules

[ibdilbert]

Something I didn't so was hold the vacuum for 15 mins before heating it.  I pulled a vacuum then immediately started to heat it.   

I assume the long wait is that any air trapped under the pressure of the bag will eventually work itself out through the air medium, aka cotton sheets?

[oztules]

I don't know for sure...... but idle speculation is that this time is when most of the air evacuates, and it will not have to travel through the viscus EVA.... but rather get pressed/sucked out of the whole system before the heating takes place.

...........oztules

[ghurd]

Oz and ibdilbert,
That is some nice work.
G-

[dnix71]

Is there any fix for a bubble? If you put a pin in it can it be sealed over in a permanent fashion or is it just better to leave the bubble alone? A bubble in hot weather will spread, won't it?

[oztules]

The cells are securely enveloped in EVA, which is tough and yet still flexible to a certain degree. I doubt the bubble could do much more than expand and contract with the heat, It would be a big ask for it to move... I don't see that as possible. It will behave like a bubble trapped in silicon (the stuff you do your spouting or stick fish tanks together with).

When the EVA has cured/crosslinked properly, you cannot get it to prise off the glass even with a razor blade or stanley knife... it is tough stuff. To separate from itself is near impossible to consider.

Thanks Ghurd.

That panel in that picture cost 50cents/watt for the cells, and 10 dollars to encapsulate... for a 60 watt panel that is small beer, and it will last the same as a commercial one I suspect.....not bad for 40 dollars plus an old window pane. The window frame (aluminum) is now on it as well.


..........oztules

[ibdilbert]

Still running test this weekend.   

Current config is still the 5.5 cfm pump, pulling 29+" vacuum, standard low melt EVA, .5mm thick, cross hashing on one side.

This time I let it sit with vacuum w/out heat for 15 mins exactly, then tossed it onto a 210 degree hot plate, and results were better, but I still got some bubbles on the edges. 



Going to change the the breather material from felt to some glass/cotton insulation, thinking it may breath better, also going to give it 30 mins and I have some different brand EVA.   Will post the results when done. 

[ibdilbert]

No bubbles this time, I'm impressed, going to have some more glass cut and keep trying to see if I can be consistent. 

[oztules]

Good stuff.
Was that with the different breathing material.?

If the more porous material made the difference, I still think the silicon bag must  not be completely secure .... otherwise it would make little difference, as the vacuum would settle evenly in the felt sooner or later. A leak of any kind would make the results different between the two.


well done anyway.

I will be doing another 2mx1m panel soon (230w), will try to document it .

.........oztules

[ibdilbert]

I used what I thought was glass matting that was once around an old discarded dish washing machine.   The material actually started to melt in the process, so it must of not been glass matting, probably some sort of spun poly whole.  

The bag is siliconed shut on three sides, and I have a magnet clamp like device on the open end.  

I'm doing another one right now, with confirmed glass insulation, the pink stuff used in walls.

*UPDATE*

2nd panel to come out bubble free.   Going to do some more until my confidence builds before doing a larger panel, but so far this method looks promising.

*UPDATE 2*

3rd time, and again, no bubbles.  Will make a bigger bag in the morning with silicone sheeting and try a larger size test panel. 

[DamonHD]

Well done!

Good to know how it *should* be done if someone is mad/DIY enough to try.

Rgds

Damon

PS. Maybe if you perfect the technique we should pin this up as a FAQ.

[oztules]

I did try to post a detailed how to story on this topic, but the forum software is not up to it. 10 pictures did not begin the tell the tale, the posting was too long, and it was all to hard for it.

I have  given up at this stage.


..........oztules

[DamonHD]

Try it in smaller chunks, like commanda's multi-part LED stuff?

Rgds

Damon

[birdhouse]

oz-
i know how different software and regs can be a big pain, and i also wish it was easier, but maybe a two or three part story could be put together???   this is one of the better (best) sites on such topics, and i know for one, i would be stoked to see a full write up on what you have achieved!  i hate resizing photos, ect, ect ect, but it would probably help a ton of folks that will be trying to do what it seems like you have nearly perfected. 

just my thoughts

adam

[klsmurf]

Hi Oztules,

I'll echo others by saying please try to put together a write up. I've put together a couple small panels just using sillicon caulk and EDPM rubber for frame gaskets. It works well, but I know they are only temporary. I've got all the materials needed to put others together properly, vacuum pump, EVA and heat lamps. I'm in the beginning stage of designing and putting together a heat box that can be reused for different size panels.    Kevin

[ibdilbert]

Hi Oztules,

I too speak for many, were all very excited to see how you have profected this methond.  A write up sure would help the rest of us, even if you have to brake it down into smaller posts or put the pictures on an external service.

[oztules]

Over the next week I will put together something. I felt a bit despondent when a (very long winded/big) post disappeared into the ether.

I will break it up into smaller parts as has been suggested.

Any preferences for what those sections/parts should be?

...............oztules

[Bruce S]

OZ;
  As a just in case could you also PM or email the post before or during the posting to maybe an admin or mod?
Your information can be very valuble and I certainly find the amount of stuff worth helping get on here as much as possible.
NOT trying to butter you up or anything. Just fact.
I'm pretty sure there is a limit on the number of pics each post will allow and unlike to older forum I don't think there's a warning on this one.
 I had a nice write up with about 10 pics and it went into vapor too.
JW was hard at work fixing limits but... he can do only so much.

If you do rewrite this maybe multi-sections.
1) panes selection, cleaning and prep
2)panel soldering and glass selection
3) selecting correct under layment and timing
4) pre-oven vacuum , oven w/vacuum  etc.
etc

Thoughts?
Bruce S
 

[commanda]

If I may,

The trick to doing these long write-ups is do it locally first with any text editor of choice, save it on your desktop or wherever, then copy & paste into the forum.
That way, if the forum barfs, you still have what you wrote originally.

Amanda

[Ovais]

Hello Oztules.

Many thanks for describing and teaching us your great work.

We will all be obliged if you can document your work more so that we novices can do it better.

Regards,
Ovais

[Tritium]

Over the next week I will put together something. I felt a bit despondent when a (very long winded/big) post disappeared into the ether.

I will break it up into smaller parts as has been suggested.

Any preferences for what those sections/parts should be?

...............oztules

A long time ago and after many post that were lost on various forums (many times because of my providers level of service) I now build in my word processor and then copy/paste to the forum if it is a very detailed post. Sometimes tedious but no lost work. Just a thought.

Thurmond