Which encapsulant is best

[bcroe]

Have you ever examined the back of a commercial solar panel?
The EVA adheres to the cells AND the glass. When the heat gun is applied to the back, it transforms from solid-flexible to near liquid. It will not go between the cells and the glass unless there is a thick solder joint preventing the cells from laying flat against the glass.
Properly done, as in the video I showed you, the EVA in its super heated state will melt (And is pulled in by vacuum, start heating furthest from the vacuum connection as possible. Work towards where the vacuum is connected so you do not accidentally clock the vacuum action. It will melt to the glass, too, isolating each individual solar cell, providing that you spaced them out enough, usually 1/8" is fine.
For example, I have a commercial Sharp panel @ 250 watts that has a bag cell, with a perforation penetrating the EVA. the cell is discolored, but it is separate from all the rest.
Just make sure you have the cells spaced far enough apart from each other. If your current cell column is too close, you can try it, but in the future, make sure they lay perfectly flat, and space them out using ceramic tile spacers from Lowes.

Some bug kept me from playing the video yesterday, but it was OK today. You said cells face
down on the glass, but the video shows them face up. Those cells are so close together, the
EVA will only make significant contact with the glass at the edges. That implies the whole mass
of cells (on edge) is hanging on the flexible EVA, not the glass; they aren't connected.

Maybe the idea is glass, EVA, cells, EVA, to join everything together? Bruce Roe

[thehandyman]

Some bug kept me from playing the video yesterday, but it was OK today. You said cells face
down on the glass, but the video shows them face up. Those cells are so close together, the
EVA will only make significant contact with the glass at the edges. That implies the whole mass
of cells (on edge) is hanging on the flexible EVA, not the glass; they aren't connected.

The cells are NOT facing the EVA. The solar panel would produce almost no energy if the glass was facing the sun that way.

You are correct, the cells he soldered together are very close. Too close. Look at a commercial panel for proper spacing. This is why I mentioned you should use ceramic tile separators from LOWES. I only showed you the video so you could understand the vacuum principle.

As far as what vacuum he used, it is a standard Hoover or whatever, floor vacuum with the detachable hose for crevices, etc. A shop vac will work.

If you want to use an elaborately engineered home brew oven, go ahead! But a heat gun will work, too. If you want to use a trash bag for suction, that is fine, too. Tape woks just as good if done properly.

All you must do is have an active vacuum between the EVA and the glass, sandwiching the solar cells. That's it. There's even a video of a guy using a hand vacuum pump to achieve it.

Edit: The ceramic tile separators used for laying or setting tile should only be used when SOLDERING the tabbing to the cells for spacing. Remove them BEFORE putting the EVA over the back of the panel. Check and double check your electrical connections and output before laying the EVA. Once the EVA is applied you won't have a second chance so make sure it is right!

[bcroe]

The cells are NOT facing the EVA. The solar panel would
produce almost no energy if the glass was facing the sun that way.

You are correct, the cells he soldered together are very close. Too close. Look at a commercial panel for proper spacing. This is why I mentioned you should use ceramic tile separators from LOWES. I only showed you the video so you could understand the vacuum principle.

If you want to use an elaborately engineered home brew oven, go ahead! But a heat gun will work, too. If you want to use a trash bag for suction, that is fine, too. Tape woks just as good if done properly.

All you must do is have an active vacuum between the EVA and the glass, sandwiching the solar cells. That's it. There's even a video of a guy using a hand vacuum pump to achieve it.

Guess the referenced video isn't very close to your process. He says the EVA must be clear
for the sun to shine through. Bruce

[thehandyman]

Guess the referenced video isn't very close to your process. He says the EVA must be clear
for the sun to shine through. Bruce

It was the best vid I could find showing the vacuum process. As I said, it demonstrates how easy it is to use a house hold vacuum to suck the EVA down.

Put the solar cells facing the glass.

Use tile separators when soldering tabs. Use 99% iso alcohol in an ultrasonic cleaner to clean cells before soldering, do not touch them except with gloves.

[bcroe]

It was the best vid I could find showing the vacuum process. As
I said, it demonstrates how easy it is to use a house hold vacuum to suck the EVA down.

Put the solar cells facing the glass.

Use tile separators when soldering tabs. Use 99% iso alcohol in an ultrasonic cleaner to clean
cells before soldering, do not touch them except with gloves.

I spent a lot of time testing cells, which I consider very important grading out before
assembly. Adding the idea of cleaning cells is making this even more laborsome. My ultrasonic
cleaner isn't nearly big enough for this. I can't really buy into having nothing between the cells
and the glass. There will always be some air in there, though I never saw some air as that
detrimental. But the glass provides the structural integrity to keep the cells from being cracked
(like some of my earlier experiments). Without a direct bond between the cells & glass, I expect
one modest whack on the edge of a panel will slide & break cells. My commercial panels have
survived more than I ever meant to happen. Exactly what do they do? Bruce Roe

[Mike90250]

EVA in the un-heated state, is a milk white sheet. When heated, it melts, goes clear, and stays clear. it IS the glue that holds the working side of the PV cells to the back side of the glass.

[thehandyman]

I spent a lot of time testing cells, which I consider very important grading out before
assembly. Adding the idea of cleaning cells is making this even more laborsome. My ultrasonic
cleaner isn't nearly big enough for this. I can't really buy into having nothing between the cells
and the glass. There will always be some air in there, though I never saw some air as that
detrimental. But the glass provides the structural integrity to keep the cells from being cracked
(like some of my earlier experiments). Without a direct bond between the cells & glass, I expect
one modest whack on the edge of a panel will slide & break cells. My commercial panels have
survived more than I ever meant to happen. Exactly what do they do? Bruce Roe

You spend a lot of time testing them, but you can't wait three minutes while they soak in an ultrasonic cleaner? How big are your cells, and how big is your ultrasonic cleaner? The oils from our skin, dust, etc will degrade them over time. You are too concerned about the cells not cracking and not concerned enough with them remaining pure.

Do you want to know how "Companies" build solar cells? Quite easily, just as I said. https://www.youtube.com/watch?v=lqHclYEEj50

They lay them flat against tempered glass, no encapsulation, (All glue degrades over time. Anything in front of the cells will likely yellow and kill the cell's ability to generate electricity. Yellowing dampens light.) then lay a sheet of the EVA and bake/melt it on. Then they put the aluminum borders around it, wire it, and it's essentially done. Some companies may have different processes but this is a tried and true way. It is also cheap, easy for the layman to accomplish, tried, and true.

Just remember a few things: The glass MUST be tempered glass (It will shatter otherwise), and for maximum life of the cells, soak them in 99% Iso alcohol in an ultrasonic degreaser before soldering. Handle them with gloves. Use ceramic tile spacers. Be as clean as possible. Lay the EVA on the back, tape it down, vacuum the air out, and apply a heat gun or put into an oven if you have one large enough.

Solder the tabs to a junction box and you are done.

[bcroe]

You spend a lot of time testing them, but you can't wait three minutes while they soak in an ultrasonic cleaner? How big are your cells, and how big is your ultrasonic cleaner? The oils from our skin, dust, etc will degrade them over time. You are too concerned about the cells not cracking and not concerned enough with them remaining pure.

Do you want to know how "Companies" build solar cells? Quite easily, just as I said. https://www.youtube.com/watch?v=lqHclYEEj50

They lay them flat against tempered glass, no encapsulation, (All glue degrades over time. Anything in front of the cells will likely yellow and kill the cell's ability to generate electricity. Yellowing dampens light.) then lay a sheet of the EVA and bake/melt it on. Then they put the aluminum borders around it, wire it, and it's essentially done. Some companies may have different processes but this is a tried and true way. It is also cheap, easy for the layman to accomplish, tried, and true.

Just remember a few things: The glass MUST be tempered glass (It will shatter otherwise), and for maximum life of the cells, soak them in 99% Iso alcohol in an ultrasonic degreaser before soldering. Handle them with gloves. Use ceramic tile spacers. Be as clean as possible. Lay the EVA on the back, tape it down, vacuum the air out, and apply a heat gun or put into an oven if you have one large enough.

Solder the tabs to a junction box and you are done.

The video looks like 4" cells, obsolete. The methods also look obsolete to me. I am sure
my panels with 60 or 72 of 6" X 6" cells used a more automated process. But for DIY you
recommend an ultrasonic cleaner big enough for 6" sq cells, along with that rather neatly
machined rack to hold them? The video says pure water, but you say "99% iso alcohol"?

You can't prioritize cleaning, sealing, testing, etc, all the essential steps must be done to
produce something useful. One tiny crack can cripple a large cell, and also the entire
panel. Any rough handling can cause disaster. So can cells not totally secure against the
supporting glass.

Then there is a precision machined template to hold all the cells in position, along with
grooves for the tabbing. Then there is a nice many position vacuum cup device to pick
up columns of wired cells, too bad I don't have one. I keep seeing people trying to pick
up a column of cells held only by the tabbing, this is just inviting disaster.

Then that vacuum sealed, temperature controlled, timed oven looks just great,
wonder what that cost?

I like what Mike90250 said, the cells are bonded on the glass as well as covered in back
(the expensive encapsulant method does that too). Unfortunately I think that ELIMINATES
the heat gun method. I wonder how thick commercial glass is?

There is one more step to DIY panels, making them WORK. The first problem is seeing if
all the cells survived the assembly process intact. i have done this by comparing the
output of several columns with good sun and a heavy load. A column with much reduced
voltage probably has a failed cell. It can be found by checking the voltage (under load) of
each cell, if you can probe wiring.

Having found a bad cell, the next problem is how to save the panel. One method is wire a
short across it and accept the reduced voltage to get full current. One of my earlier panels
has several cells shorted due to the fragility of 6" sq cells. The 3" X 6" cells were a lot
easier to get done intact, might be better for first efforts.

I think someone said the encapsulant could be cut and another cell put in. I have not tried
this operation.

What we really need is a video showing all the things that won't work. Bruce Roe

[thehandyman]

The video looks like 4" cells, obsolete. The methods also look obsolete to me. I am sure
my panels with 60 or 72 of 6" X 6" cells used a more automated process. But for DIY you
recommend an ultrasonic cleaner big enough for 6" sq cells, along with that rather neatly
machined rack to hold them? The video says pure water, but you say "99% iso alcohol"?

YOUR methods are obsolete. Name one solar company that assembles panels exactly the way that you do. Where are your robotic arms? Where are your vacuum carriers? Unless you are building them *exactly* like Sharp or Kyocera, why are you arguing with a legitimate answer to your question?

You seem to want to build a panel but have no interest in anything other than glue to stick them to the inside of a sheet of glass. Making sure the cells are clean? No, not for you.

Fine, skip that step.

Personally, I would rather not go through the trouble of buying the cells, slathering them with glue (That you cannot guarantee will NOT yellow over time, reducing efficiency) tabbing them, buying the glass, buying the aluminum, then realizing that they weren't perfectly clean and were now showing signs of oxidation under the glass. You can buy an ultrasonic cleaner from Harbor Freight that will handle a few cells at a time for under $100. They have 25% off coupons available almost all of the time.

And yes, use Isopropyl alcohol, 99% electronics grade not water, which can leave scale.

You can't prioritize cleaning, sealing, testing, etc, all the essential steps must be done to
produce something useful. One tiny crack can cripple a large cell, and also the entire
panel. Any rough handling can cause disaster. So can cells not totally secure against the
supporting glass.

When it comes to longevity, I can try. Apparently many solar panel manufacturers do it this way. Apparently they have for some time. Do it your way, though, you seem dead set on it.

Cells I got a few months ago were amorphous silicone and quite flexible. I wonder what cells you are using that are so brittle and fragile?

Then there is a precision machined template to hold all the cells in position, along with
grooves for the tabbing. Then there is a nice many position vacuum cup device to pick
up columns of wired cells, too bad I don't have one. I keep seeing people trying to pick
up a column of cells held only by the tabbing, this is just inviting disaster.

It's funny you say that. "Precision machined". My Sharp 250 watt panel has the cells offset, aligned this way and that. They are up and down fine, but look almost intentionally staggered. So that precision template certainly did them no good with that panel. Yet, it still produces usable electricity.

Then that vacuum sealed, temperature controlled, timed oven looks just great,
wonder what that cost?

As much as a feet of tape and a kitchen table. In the first video, it is pretty evident how EVA melts against the cells, encapsulating them. It's hard to screw it up. Apply heat and watch until it melts. It's more intensive than "Soak it in glue and slap it against some glass" but it's doable. Or, you can buy the wood and etc for the oven in the link Mike provided. Precision control is not that difficult with that oven, if you are going to be building more than just a few panels.

I like what Mike90250 said, the cells are bonded on the glass as well as covered in back
(the expensive encapsulant method does that too). Unfortunately I think that ELIMINATES
the heat gun method. I wonder how thick commercial glass is?

What chemical do they use to bond it to the glass? What company does this? Unless you use that exact chemical, and not a substitute, you are gambling with your panel. As I said, I have old Carizzo plant cells that are quite yellowed. I also have some sheet glass panels that are so yellowed in front of the cells that they no longer produce electricity. Is that what you want? Because that is what you're going to get. Disposable, throw away panels.

Do you know the optical characteristics or opacity of sil-gard?

What wavelengths of light it restricts, and what wavelengths it allows? Do you know what visible and invisible wavelengths are needed to generate electricity in your cells? You might be intentionally restricting output by encapsulating them in glue. Over time, as they yellow or grow dull, restricting light, your output will reduce even more.

Commercial glass is no thicker than you can buy from any tempered glass manufacturer. You would be surprised at how thin and flexible it actually is.

There is one more step to DIY panels, making them WORK. The first problem is seeing if
all the cells survived the assembly process intact. i have done this by comparing the
output of several columns with good sun and a heavy load. A column with much reduced
voltage probably has a failed cell. It can be found by checking the voltage (under load) of
each cell, if you can probe wiring.

I thought you were testing the cells thoroughly before tabbing them? Certainly testing them individually would have found a bad cell before tabbing.

Having found a bad cell, the next problem is how to save the panel. One method is wire a
short across it and accept the reduced voltage to get full current. One of my earlier panels
has several cells shorted due to the fragility of 6" sq cells. The 3" X 6" cells were a lot
easier to get done intact, might be better for first efforts.

It sounds like you are using some fragile cells. In my Sharp panel I am going to have to do just this, bypass a cell that literally has a hole through it.

I think someone said the encapsulant could be cut and another cell put in. I have not tried
this operation.

If they used any sort of sealer to seal the cell to the glass you are likely not going to be able to replace the panel without a lot of scraping and risking nicking the surrounding panels. It's worth a try, is my guess. I might try it with my Sharp panel rather than stressing myself out about possible damage to the panel.

What we really need is a video showing all the things that won't work. Bruce Roe

I would like an explanation of why the things did not work. For example, "The cell failed to produce electricity after three years" is this because they were not washed in alcohol, and oxidation corroded the cells? Is it because the encapsulent glue formed a light blocking, IR or UV blocking film that restricted light production to the cell? It's easy to say "This does not work" but never understand why (The real reasons) it failed.

You will also never know until you try. Personally, working with electronics for over twenty years, getting it right should not be that difficult. I applaud you for even trying. I tend to take what people on the net tell me with a grain of salt. Some people love to discourage and tell you you can't do it yourself. I am telling you you can and easier than you think.

It wouldn't be hard to build two small panels, one encapsulated in sil gard the other with only EVA. See what if, and how your output changes over time, if at all. That's the only way to know for sure.

I could be totally wrong and sil-gard be good for a hundred years, never becoming opaque and reducing output.

[russ]

DIY panels are generally a waste of time - why get too excited?

[inetdog]

What we really need is a video showing all the things that won't work. Bruce Roe

They are all out there on the internet, just not properly labelled as not working.

[russ]

What we really need is a video showing all the things that won't work. Bruce Roe

Generally called youtube - a few exceptions but not many.

[bcroe]

YOUR methods are obsolete. Name one solar company that assembles panels exactly the way that you do. Where are your robotic arms? Where are your vacuum carriers? Unless you are building them *exactly* like Sharp or Kyocera, why are you arguing with a legitimate answer to your question?

You seem to want to build a panel but have no interest in anything other than glue to stick them to the inside of a sheet of glass. Making sure the cells are clean? No, not for you.

Fine, skip that step.

Personally, I would rather not go through the trouble of buying the cells, slathering them with glue (That you cannot guarantee will NOT yellow over time, reducing efficiency) tabbing them, buying the glass, buying the aluminum, then realizing that they weren't perfectly clean and were now showing signs of oxidation under the glass. You can buy an ultrasonic cleaner from Harbor Freight that will handle a few cells at a time for under $100. They have 25% off coupons available almost all of the time.

And yes, use Isopropyl alcohol, 99% electronics grade not water, which can leave scale.



When it comes to longevity, I can try. Apparently many solar panel manufacturers do it this way. Apparently they have for some time. Do it your way, though, you seem dead set on it.

Cells I got a few months ago were amorphous silicone and quite flexible. I wonder what cells you are using that are so brittle and fragile?



It's funny you say that. "Precision machined". My Sharp 250 watt panel has the cells offset, aligned this way and that. They are up and down fine, but look almost intentionally staggered. So that precision template certainly did them no good with that panel. Yet, it still produces usable electricity.



As much as a feet of tape and a kitchen table. In the first video, it is pretty evident how EVA melts against the cells, encapsulating them. It's hard to screw it up. Apply heat and watch until it melts. It's more intensive than "Soak it in glue and slap it against some glass" but it's doable. Or, you can buy the wood and etc for the oven in the link Mike provided. Precision control is not that difficult with that oven, if you are going to be building more than just a few panels.



What chemical do they use to bond it to the glass? What company does this? Unless you use that exact chemical, and not a substitute, you are gambling with your panel. As I said, I have old Carizzo plant cells that are quite yellowed. I also have some sheet glass panels that are so yellowed in front of the cells that they no longer produce electricity. Is that what you want? Because that is what you're going to get. Disposable, throw away panels.

Do you know the optical characteristics or opacity of sil-gard?

What wavelengths of light it restricts, and what wavelengths it allows? Do you know what visible and invisible wavelengths are needed to generate electricity in your cells? You might be intentionally restricting output by encapsulating them in glue. Over time, as they yellow or grow dull, restricting light, your output will reduce even more.

Commercial glass is no thicker than you can buy from any tempered glass manufacturer. You would be surprised at how thin and flexible it actually is.



I thought you were testing the cells thoroughly before tabbing them? Certainly testing them individually would have found a bad cell before tabbing.



It sounds like you are using some fragile cells. In my Sharp panel I am going to have to do just this, bypass a cell that literally has a hole through it.



If they used any sort of sealer to seal the cell to the glass you are likely not going to be able to replace the panel without a lot of scraping and risking nicking the surrounding panels. It's worth a try, is my guess. I might try it with my Sharp panel rather than stressing myself out about possible damage to the panel.



I would like an explanation of why the things did not work. For example, "The cell failed to produce electricity after three years" is this because they were not washed in alcohol, and oxidation corroded the cells? Is it because the encapsulent glue formed a light blocking, IR or UV blocking film that restricted light production to the cell? It's easy to say "This does not work" but never understand why (The real reasons) it failed.

You will also never know until you try. Personally, working with electronics for over twenty years, getting it right should not be that difficult. I applaud you for even trying. I tend to take what people on the net tell me with a grain of salt. Some people love to discourage and tell you you can't do it yourself. I am telling you you can and easier than you think.

It wouldn't be hard to build two small panels, one encapsulated in sil gard the other with only EVA. See what if, and how your output changes over time, if at all. That's the only way to know for sure.

I could be totally wrong and sil-gard be good for a hundred years, never becoming opaque and reducing output.

Well, I'm trying to work through a way that a DIYer can succeed. Certainly he will not have
the capitol equipment available to even a modest factory operation. If you are going to
just attack me instead of dealing with the issues, then this is going nowhere. Bruce Roe

[russ]

YOUR methods are obsolete. Name one solar company that assembles panels exactly the way that you do. Where are your robotic arms? Where are your vacuum carriers? Unless you are building them *exactly* like Sharp or Kyocera, why are you arguing with a legitimate answer to your question?

Your BS is wearing thin. Some people want to do it for fun

[Wiliwil3]

I made quite a few attempts back then, starting with what I saw on the internet.
They all failed in a very short time. As a result I came up with this scheme. This
last panel is a success, all good cells, and delivering the expected power. Guess
it needs to be on display somewhere with the other stuff. Maybe power my
stored vehicle battery maintainer, which can tolerate the intermittent PV power.
About a year old, has several times as much encapsulant as allegedly needed.

All those lessons taught me there was no way to come into the same ballpark
of practicality of commercial panels, at under $1 a watt. There are over 150
commercial panels here, 2/3 in daily service. Bruce Roe

Thank you