Help mounting encapsulated cells

[ghurd]

The cells are encapsulated, front and back, with whatever it is they use on solar yard light type cells.

They have very short tabs coming out the sides.  Not out the back.

Measure something around-about 1x2", rectangular.

I need to mount 16 cells into an "array".  8x2, all in series.

Wood is no good.  It will be outside and permanently installed.

Neither is metal, unless someone has ideas about how to be sure the tabs won't meet the metal.

I am leaning toward plexiglass, because it is cheap and locally available at the surplus scrap pieces of everything shop, and I can heat and bend it to make the mount and array as a single unit.
Some holes in the plexi will give a place for the hot glue to bite mechanically.

Can anybody think of a better way to assemble this monsterous solar array?

Any crazy ideas are welcome!
G-

[dang]

The original hot-glue sticks were pure EVA in rod form - they offer high temperature glue sticks these days..

Care to bake it and spread EVa like frosting?

[ghurd]

The original hot-glue sticks were pure EVA in rod form - they offer high temperature glue sticks these days..

Care to bake it and spread EVA like frosting?

Then what?
They have to be "mounted on something".

They are already covered front and back with whatever goop they cover the front of solar yard lights with.  The only thing not covered is the little tabs.

I kind of figured on doing the frosting thing to hold them on to something.
Problem is I don't know what to frost them onto!

Hot glue does not stick so well to some slick smooth surfaces, and I always had good luck with a few holes drilled and filled, and some more added to the rear with overlap.  Sort of like a rivet made of hot glue?


Do you (or anyone else) see any issues with using plexi to stick them onto?

I have used plexi for a slew of other things, but nothing quite like this, and I'd rather not learn a known issue the hard way.

A couple pieces of metal blocked up at the desired angle, plexi layed over the corner, careful application of heat with the <$10 w/coupon HF dual-temp heat gun, and it would be a good solution for me, IF plexi is good for the purpose!

I may have used surplus scrap Lexan too, because i used some "plexi" that didn't behave quite like it usually does.  I expect the local scrap store would call anything even remotely similar to plexi, plexi.

After seeing that wiki pic of shooting some Lexan into an AL block at 23,000FPS, kind of wondered if that would have caused the behavior discrepiencies!

To save everyone from googling it,
http://en.wikipedia.org/wiki/Lexan


I know I should have got a pic 1st, and didn't.
For some reason, my daily-use camera is not working even after charging it half a day, and the too-high resolution camera is in need of batteries (which I just discovered there are no AA alkalines and the rechargables are all too dead), leaving a $19 cell phone for the camera right now.

This is them, best I can do, back (left) and front, showing some reflection of the edge curvature of the 'goop', and how long the typical tab is...

[rossw]

Just thinking out loud.... but PV cells are made of.... silicon (sand).
Glass is made of.... silicon (sand)
Plexiglass/acrylic/polycarbonate/steel etc will all have quite different expansion coefficients, I would think.
Would it be practical to get some surplus toughened or laminated glass (purely for strength) and bond them to that? Or is that equally impractical? Toughened glass you can't drill holes in, but ordinary float glass, and laminated glass you could.

Surplus glass is readily available and cheap...

[dang]

Fuse them to a Beryllium Oxide ceramic electronic insulator!

http://search.ebay.com/160920113233 <--- 2-3/4" x 8" x 1mm titanium plate?  $15 shipped from Latvia!

http://search.ebay.com/160919642177 <---- Carbon fiber twill texture panel 2mm x 2" x 8" rigid sheet $7 shipped (surfboard resin)

Goodwill / Salvation Army 50¢ 4" x 8-1/2" aluminum bread pan bottom with cut down walls to make rigid panel with mounting tabs?

Goodwill / Salvation Army 75¢ aluminum yardstick or carpenters square?

Anyhow - I just used up all my 3m 5200 sealant, they have fast & slow cure varieties that might be perfect encapsulation - spendy stuff but as near forever as you could hope for.

[Tritium]

Better take a look at the Beryllium Oxide ceramic MSDS FIRST!

http://www.americanberyllia.com/lit/Beryllium_Oxide_MSDS.pdf

Thurmond

[ghurd]

Fuse them to a Beryllium Oxide ceramic electronic insulator!
Goodwill / Salvation Army

Correct.
I always overthink the possible issues.  That is why I asked!

I have a 121% fully stocked kitchen worth of high quality items nobody will ever use ever again.
No need to waste my gas and time going to a thrift store.

Just thinking out loud....  glass....  Plexiglass/acrylic/polycarbonate/steel etc will all have quite different expansion coefficients, I would think.

Can drill hardened glass, or basically grind through it with brute force and the right bits, a gazzillion RPM air powered 'dremmel tool' and such.

Expansion coefficients, in my tiny brain, would be delbt with in the layer of hot glue 'frosting'.
The stuff is kind of flexable when cool.  A thick layer of frosting should deal with the expansion coefficients?

No clue if this is any good at all: eBay item- "Solar-Tite 7741-TE White Backing Solar Encapsulant"
It will not help my situation (given the cost), but it may help someone else.
G-

[bj]

Chiming in late ghurd, but I vote plexi.  I think lexan is more or less the same.  In my endless
messing around with cells, I bonded one to lexan with EVA.  Just a bare cell.  The lexan stood
up to the heat OK.  The cell output seemed the same.  And it's been mistreated enough to get
it all scratched up.  Still works.  Yours are coated, so should be even more robust.
Just something I have tried, that worked.

[philb]

The laminate panels I mounted to superstrut steel frames last spring are still going strong with no separation or delamination. They had edges like you described. I used Dap 3.0.

If you were to mount the cells on the top of the plexi, I think it would work. Also Shoe Goo for plumbers makes a clear product that stays plyable and very tough.

At any rate, you are going to have different coefficients of expansion between the cells and substrates. I would use something flexible.

[ghurd]

Plexi and hot glue it is.

Got the plexi free.     I work with a girl whos hubby manages surplus scrap place, she offered, I said Great because it would save me 90 minutes (45 minutes of driving, 45 minutes of sorting through the scrap piles).

Now only need to figure out an enclosue size for the NiCds and diodes,
and solder the cells and diodes together,
and bend the plexi at the proper angle,
and...

Gosh.  Its almost finished!  LOL
G-

[ghurd]

Plexi bent very nice.
Heat gun at the bend, with the plexi laying on 2 pieces of sheet metal as a jig.
The hot glueing was quite an operation.  Required 2 people.




Another plan for the tiny PVs: almost pocket sized solar phone charger.
Little folding box, 8 PVs, about 4.9V open circuit, roughly 4V at peak power, tiny little boost converter with USB output (not here yet).

Big fun in small packages.
G-

[philb]

That would be perfect for backpackers and emergency (or regular) cell phone charger. Where did you get the cells?

[bj]

  Pretty slick Ghurd.  Those are nice little cells.

[ghurd]

The cells came from fleaBay (where else would anyone find something like that?).
Bunch of sellers selling the same thing, "Drop Shipped" from <gulp> powerjack in China.
Advertised as weatherproof / waterproof 0.3W 0.5V 0.6A.  Usually come in lots of 10.  Usually sell for about US$2.25~2.50 per 10, including S&H.

Be Advised: Same guys sell them is larger sizes too.  One 0.5V cell at 3W, 4W, maybe larger.
They are NOT so nice.
I can not decide if the coating is the issue, coating separated during shipping, if the coating is actually separated (coating looks fine at the edges), or of the cells looked 'different' before being coated.
They make juice, but didn't have any decent sun to test the output under decent conditions since they started arriving.
Besides, they are too large to do what I want to do.  Connecting 6 or 8 or 18 of them would make a pretty large assembly.
G-

[ghurd]

For those who have not figured it out, or later when everything is old,
this post is related to the post here,
http://www.anotherpower.com/board/index.php/topic,708.0.html
G-