Making decent solar panels part 3

[dave ames]

Cheers Harold,

we are interested in fabricating some smaller/ lower wattage modules but still at a 12 volt nominal system. when we cut a .5volt 4amp cell in half we should get two cells that are 1/2volt each and 2amps..in quarters we see 4 cells 1/2volt each and 1amp.

i have fun goofing around with smaller systems, here i'm looking for about 10 watts to run some spitting gargoyles my lady friend has around the swimming pool..she calls them "fish" but they look like the old hand drawn monster fish we see on old nautical maps....beautifully ugly?

and yes we are still seeing the 10 watts from the cracked panel, soo we will bake another layer on top and post the outcome.

we will be watching for posts from the rain forest in a few short weeks Harold. this stuff is a ton of fun!

kind regards, dave

[DanG]

I tried a rotozip diamond blade cutting wheel on the evergreen string-foundry type wafers a while back.

The setup took great delight in converting the polycrystalline wafers to blue sand from vibration resonance, a combination of unsmooth feed rate and either the used rotozip bearings were loose (not purpose bought new) or the wheel was out-of-round from the factory.

I had a damaged 'Concrete Core' drill that I nabbed the diamond segments off of, and made a draw-style knife sharpener to narrow the wheels cutting edge down to a knifes edge and true it up some, but I found the clamp setup I was using was ringing with vibrations and still would not feed without some binding and chipping the weak 'silicon bubble' crystal of the Evergreen cells.

Having a thin true cutting wheel and steady cutting head mount and a well calibrated automated feed system is vital.

The magnetic clamp is a great twist - I was working on a thin foam vacuum tray when I got, umnn, distracted...

[Madscientist267]

Why not score the cells, rather than trying to cut them outright?

Or am I missing something again? LMAO

Pure speculation on my end - never tried cutting them myself.

Steve

[dave ames]

...it's nice to be able to get another crack try at something that went south and salvage what might have been a total loss.

we vacuum baked another layer of EVA and glass over top of the cracked panel without any drama at all..was a little worried about the glass drifting out of alignment so we taped the corners square with painters tape then bagged and baked with our vacuum pump and airwick (bath towel) as has proved itself here under some not soo controlled conditions with good results.

not much new to see, taped corners:


vacuum bag:


kitchen oven, when the cheese and kisses is out:


final version: glass/eva/glass(cracked)/eva/cells/eva/tedlar backing...this is one solid brick



some suspense now.. as we have no hope for even a moment of full sun here for the next several days. so while waiting for some sun we have it out on the picnic table in the snow and rain.

DanG,  had to laugh a bit at the self destruct description of the wafers..turned to blue sand..my first few went to..chopped salad if we use the "chards" spelling...i see i'm using "arbour" now in a creative way two! <-pun in ten did

i think your theory's are sound as to some of the cutting problems. really believe you had murphy on the run with the foam vacuum hold down clamp idea. sure to have done wonders in the vibration department and that's a win. it really comes down to speeds and feeds in the end, ..once we have a stable working platform. one consideration if you choose to revisit the project, might be a larger diameter cutting blade. this 4" $8 blade is a winner..let's us achieve a working speed (*5,500sfm) at a lower rpm (5,300rpm) -number 2 on this dremel, which helps with that resonant vibration demon. a 1" disk would have to spin at over 20K to get us there.


* this surface feet per minute recommendation is my opinion only, worked up with material process bracketing techniques...(a fancy title for trial and error)

oztules has provided a way for us to have long term weather protection now for the home brew module and that was always the real killer of diy pv...i expect this panel might last longer than i will.

i would urge others to jump in and have a go.

kind regards, dave

[Harold in CR]

 Nice, Dave
 So, you added a layer of EVA and another layer of glass to the front side of the broken panel, correct ?? 

 It will be interesting to see what production you have from that panel.

  Do you have a similar sized panel, undamaged, to compare outputs ??

 Nice job.

[SparWeb]

Dave,
They keep looking better every time!

[oztules]

I will guess at a small drop in output, but a good panel none the less.

The table will cop a beating next time they clash. That is one robust unit now.... and you have proved the laminated windscreen process.

Gee, you get a lot more latitude in the kitchen than I would dare to take... well done.

Sparweb said it best..... they are getting better all the time.

Nice work Dave, and thanks for trying it.



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

[klsmurf]

i would urge others to jump in and have a go.

kind regards, dave

OK, Here we go. A few weeks back, I built me an "Easy-Bake-Oven" to try out the "Oztules Method". Here's a couple pics of the results.

This is the finished product on try #2. I am very pleased with the results.

The only bubble was here. You can maybe see the extra solder. These cells were clipped tab ones that I just extended, so there sometimes tough to get real smooth. I believe Oztules has previously mentioned to try to keep the soldering smooth. The vacuum actually popped (cracked) that corner as you can see. The output of this half panel is 9.75V and 3.5A.

[artv]

Oz and Dave you guys seem to be the top dogs on this thread so I''ll direct this towards the both of you.

First of all I know absolutly nothing about solar, other than they look like big pieces of glass , with a bunch of little rectangles under the surface.
I've read this thread from "part 1" through to present.

I would like very much to give it a try but, the cells (pv) you are using, can you make these yourself or do you have to buy them??

Also do you melt the plastic over top of the cells, to stick them to the glass ,to prevent them from moving due to expansion and contraction ,when they are outside in the sun??

 I've got glass,I've got plastic,I've got tyvek and I've got the bug.......just need some cells and a little guidance...excellent thread...........the more info the better.........you people are doing great work.........and I thank you for that.......artv

[klsmurf]

Here's what not to do. GET IN A HURRY! I use a 1500W space heater and 2-250W heat lamps (brooder lamps to us farmboys). I've got the lamps wired to a dimmer so I can control the heat somewhat. I use them mainly to hpre-heat the box and panel. This does help in the vacuum process. I got in an excitable hurry, (brain-fart) and forgot to put in the deflector shield above the heat lamps. Have you ever seen oil separate on a hot skillet? The panel is sealed well at the edges and still hits the Volts and Amps, but it is ugly.



 Just got a roll of EVA the other day, so I'll be making some more, maybe this weekend.      Kevin

[oztules]

Good to see you have results that will allow you to fine tune it and get excellent panels.

I don't know and have not needed to do it, but Dave has... and that is to redo the panel in the oven. Make sure you pull a perfect vacuum, and see if the bubbles migrate out of there. I cant see whats to lose by trying, and we may find out more about how friendly this eva stuff is..... you did clean the glass with alcohol didn't you?

The more folks do this, and the more mistakes made, the more we find out why it works well.

The trouble with the first one coming out perfect, is we don't know exactly what we did right. We need a few problems so as to know what things are critical, and what things are small beer.

I find that perfect bag sealing is no 1.

Preheat is critical to getting no cracks... especially for big cells ,so the soldered tabs can sink into the soft but not melted EVA..rather than cracking the cell.. remember the glass needs to come up to 50 degrees or so, not just the oven air..then hold the vacuum on for 15 mins or so before hitting 65c

Wicking material must work well if you have the slightest leak.

Hotter is better for glass adhesion.... and so is using alcohol to clean the glass.  I now  try to get at least 110c or more for the last 30 mins.

Anyone else have any "golden rules" to add?

If we all make enough mistakes to find every problem, we should be able to come up with a totally fool proof recipe.

I have now made a lot of panels (over 2kw) and must be inadvertently doing most of the right things, not all of which I am aware I suspect. So we need more testers.

The oven is a useful tool for other things..... like curing epoxy when the weather is too cold:




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


oh and dont attack poor defenseless tables with the panels

[oztules]

Artv,
"I would like very much to give it a try but, the cells (pv) you are using, can you make these yourself or do you have to buy them??

Also do you melt the plastic over top of the cells, to stick them to the glass ,to prevent them from moving due to expansion and contraction ,when they are outside in the sun??

 I've got glass,I've got plastic,I've got tyvek and I've got the bug."

Skip the tyvek, just use the plastic on the back. The tyvek is temp sensitive, and may cause you some problems. Plastic seems much more friendly.
You won't bother trying to make pv cells. Firstly they are dirt cheap to buy, and secondly they require stuff and equiptment you could not afford in a dream.

The eva bonds the cells, the glass, the backing plastic (or whatever you use) into one solid? mass. If you follow the thread of part 2 again, and try a test cell, all will reveal itself. Just do it step by step, and it will all happen for you.

If I can do it, anyone can.


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

[dave ames]

hey klsmurf,

thanks for the look Kevin, very clean job! i take it we are going for some 18 cell modules then series them up for a 12v system? sounds like a good plan. heck, if the overheated trial panel is still giving us good output ..i'd still call that a victory and use it!

and totally agree that the more errors we report the larger the knowledge base will become and the less repeats of screw-ups will occur..no one likes to make mistakes.. but for me it only starts to get upsetting when i make the same one over and over again.

i was a bit leery to have a go, as oztules makes everything he does look easy so it's hard to use him as a gauge for us mere mortals. so afraid it's up to the rest of us to fill in that void (the mistakes).

had some breaks in the clouds..enough to put a check mark in the win collum!

some numbers @ noon:

VOC:  21.4
ISC:  880mA  ..saw some higher flickers as the clouds did that weird edge thing.
into a 12.6v battery 730mA
into a loaded (with 10 ohm) battery 820mA

voltage into some power resistors:
8.7v into 10 ohms
16.1v into 20 ohms
17.2v into 23 ohms

a real 10 watt module ! WOO HOO 

harold, i think you see what happened now? we screwed up wanted to help with the knowledge base and broke this glass then layered another right over the top! can still see the cracks but it's sealed ...but good.

cheers Sparweb, now if we can just drag you into this crazy new cult...

hi atrv, what oztules said, just dive in and try a few small test runs! it's good fun win or lose. all the info is right here!

thanks again oztules you have been very giving with your knowledge and tolerant with postings in your thread.

cheers, dave

[klsmurf]

Thanks Dave. Yes, I plan to frame these panels end to end, route wires through the center style and use just 1 junction box. I waste some buss wire doing it this way, but I have about 8 more pieces of glass this size. They're from storm doors, tempered, with factory ground edges.

i was a bit leery to have a go, as oztules makes everything he does look easy so it's hard to use him as a gauge for us mere mortals. so afraid it's up to the rest of us to fill in that void (the mistakes).

Yes, after all his work with his chainsaw and his laminator, we'll need to start calling him the "Wizard of Oz".

[TomW]

Yes, after all his work with his chainsaw and his laminator, we'll need to start calling him the "Wizard of Oz".

Pay no attention to that man behind the curtain...

[SparWeb]

cheers Sparweb, now if we can just drag you into this crazy new cult...
...
cheers, dave

Wouldn't you know it, when I mentioned this interesting story to my wife family business manager, before I could say how interested I was in baking some panels of my own, it had already touched off a tirade about people building things themselves when they can buy it.  Not going to get into the details how that conversation went, but clearly the lesson (as I see it) about saving 5000$ putting electric power into "her" barn is not deeply rooted in her mind.  This will take some convincing.

[oztules]

Well done Dave.

 I would not have hoped for much more watts.....even using "proper glass", and you have a much stronger panel than even tempered stuff now. Even the table will cringe as you take it past.

You have successfully done what I have not tried.... made laminated glass.
What temp profile did you use, and how did you accomplish this with using the bosses oven. (details are all important)

Others making small panels will benefit from your example of both oven usage, and time  and temperature profile/s.

This could make it even easier for folks to get their feet wet, as they  need even less equipment to give it a go.

Oven bags (to cook in) would allow higher temps (stay less than 150c), and more rapid panel cooking, and very reliable glass adhesion. A sniff of high temperature seems to make it stick big time. Lower temp profiles need time ... and more time.

This glass adhesion has always been at the back of my mind when doing every panel. Now I do all the right things,and usually hold it above 90c( to 110c) for at least 90 mins..... then I wimp out, and push the oven as far as I can for another 30 mins. The bag's integrity may fail in this period,, but it seems not to matter, and the extra time and temp will aid in long term adhesion I'm guessing.

Once again, more folks doing it will result in better methods..... but I think we have started a new trend in panel making, and it looks the goods this time.

Well done with the fragility test. Thanks for the look and fearless testing.


Stephen....... sometimes it is difficult to comprehend how they think. ( and sometimes I'm not convinced that they do )


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

[Madscientist267]

My wife doesnt get it either.

Why buy something when I can make it myself or modify something I already have and make it better than what I would buy? And for cheaper? And NOW?

This falls on deaf ears.

I think it's a 'manager' thing 

Without people like us that actually LIKE to do things for ourselves, we'd be stuck only with whatever the world had to offer. And lookie what happens when we share about it... the results get even better.

Maybe our 'managers' need a few bean counters. Or something. Works for corporations, till the curtain closes that is. 

Steve

[zap]

Without people like us that actually LIKE to do things for ourselves, we'd be stuck only with whatever the world had to offer.

"Fire good!"

[dave ames]

Others making small panels will benefit from your example of both oven usage, and time  and temperature profile/s.

This could make it even easier for folks to get their feet wet, as they  need even less equipment to give it a go.

one important observation was the need to keep the plastic vacuum bag from touching the sides (or any part ) of the oven, we used something, towel/newspaper/cardboard on the underside between the bag and oven rack. then a towel on top to keep the folded up edges away from the top of the oven. maybe just wrapping the whole thing up like a christmas package with paper would be less involved?

this oven has two adjustable racks. the lower one on lowest track we covered with foil (above the heating element) and set the upper one to give us enough top clearance. the lowest digital temp setting for bake starts at 170*f/75*c..too hot for pre heat..we brought it up to 170* then shut it off.
 
in the mean time we have assembled our glass/eva/cell/eva/backing layer then some kind of air wick (old bath towel) and slipped it into a contractors garbage bag (that oven baking bag, pot roast/turkey bag is a great idea) and pull a partial vacuum (just enough to flatten the bag a bit) and fold any extra plastic back over the top with something to hold the folds on top. and put it into the "now cooled off a bit" oven..sorry, the temp at this point is unknown? guessing still up there but much less than the 170* we use a cloth cover to "seal" the partially open oven door..

....after 15 minutes or so we start the vacuum pump back up and run it for 15 minutes..then turn the oven back on set at 170*..run it at 170 for 15 minutes then start bringing the heat up in 10 degree increments every 5 minutes stopping at 230*f/105*c.. (these bags seem to give out at anything much higher) already at 45 minutes here..now we let it run for a goodly amount of time, an hour or so at 230*..getting impatient now but try and wait here -> an hour seems like a really, really long time! we pull it out after an hour clean up any eva and backing overlap along the edges with a razor (a tiny amount of overlap seems to be a good thing) and put it back in the oven and bake it at 275*f/135*c for another half hour.

we let the vacuum pump keep running through this whole process..even the unwrapping part for another 10 minutes. the now free running pump has a chance to cool down? ...just seems like a good idea, but probably not needed.


a cleaner look at the profile:

layered up and bagged in warm oven at ~120*f  for  15 minutes

then pull full vacuum for 15 minutes at ~120*f  ..listen to sound of pump <- a gague would be a better indicator. (can't find the hose and gague set)

push the temp up every few minutes in 10 degree increments stopping at 230*f

hold 230* for an hour ..listen to the pump <-if the sound changes we have lost our seal..if it's still too early (you decide) pull the bag out and slip another right over the leaking one and back in the oven it goes..listen to the pump.

after an hour remove, unwrap and trim.

back in the oven for a half hour at 275*f/135*c

let it cool a bit and then hit something hard with it to test...repeat the process with the now cracked panel with another eva/glass layer.

or we can skip that last bit and just use it with the single glass layer.. -> recommended 

no worries here using the stove. conversation was something like this

me: honey, when are you going to be out for a few hours? i want to use the stove to vacuum laminate some solar cells. it may get loud and foggy in here for a while.

her: i'll be out all afternoon. oh, that's what you dragged that HVAC pump out for?

only a few things are off limits in the kitchen. they include: no carburetors or transmissions on the table and no hoot owls in the freezer. ->the owl thing only recently made the list..oh, and no unattended exposed electrical stuff, after "the electrical tickle incident".

very reasonable she is this one. even helps me raise and lower the mill.


a good starter project might be three 3x6 cells tabbed and bussed in a standard 8 1/2 x 11" picture frame. we can see how it works and play with the finished product as a 1.5v battery charger..good times!

cheers, dave

[Madscientist267]

I think you guys have talked me into it... I'm going to have to give this a shot at some point in the near future. I'm getting itchy for more power, so I might just bite the bullet and go this route instead of buying them.

Oh, and...

very reasonable she is this one. even helps me raise and lower the mill

Sounds to me like that qualifies her for "upper" management... 

Steve

[Harold in CR]

 Hey Oztules
 I have been trying to order the EVA for 2 days. Page says processing, after filling out the order page. NOTHING happens after that.

 Did you or anyone else have the similar problem ??  Thanks
 

[oztules]

Great write up Dave..... and good advice on the after heat. I will do this as well.

Harold, I have had no such problem.... but try another brand of browser. I think I was running firefox at the time. (linux).

Madscientist267..... it's worth it, and good fun.

Dave has proved that even double layered laminated glass can be done. Now there is no barrier for anyone. I figure the laminated one will be stronger than the tempered, and will certainly keep going when standard ones have disintegrated.

Window glass may be back in vogue. (laminated)






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

[klsmurf]

Harold,  It took about 4 days for them to process my order and to be listed as shipped. It didn't take long to get here in the US. Less than a week.    Kevin

[bsafe10]

I have a few flexible stainless steel solar cells (sorry no pictures) that are 2.1v and 3.5 amps, they are approximately 8"x10" .
I intend to join  nine of them together to approximate the foldable Solar array for camping made by Brunton.
I would like to use Oz's brillient (sp) technique to bond the panels to a stable, non-yellowing, non- fogging plastic to take the place of the glass in Oz's sandwitch. Suggestions would be apreciated, including suggestions for removable  non stick materials that could face the EVA in the vacume bag that would result in a EVA-flexible solar cell- EVA sandwich. Hmm... I will have to see how the EVA binds to nylon.
I wonder if that is how scuba Bouancy compensators are made?
 I ordered EVA from Winnie at Mars Rock Solar and it took about eight days to the states.
Unless a better idea presents itself ... I am going to join the cells with stranded wire (14ga.) saved from an extension cord. I am hoping it will hold up to multiple flexings to join the cells and form a hinge.


Thank you,
bsafe10
bsafe10   

[Harold in CR]

 Problem I am having, is, on the page from Oz's link.
 I changed the amount to what I want, then, clicked BUY NOW Button. Took me to a page to enter all my info and shipping address. When all was entered, I put in the "CODE" figures, and clicked BUY NOW Button.
 
 Screen lower left says DONE. On the page, lower right, says Processing, with the active icon clock looking thingy going around.

 3 separate times, I have done this, and waited over an hour to get to the next step. Never happens.

 I also tried clicking Shopping Cart, to work backwards, so to speak. Same page loads, enter all info and wait an hour and never get to the next step.


 Seller is Winnie Wong. I tried to contact her. Says "Page not found".

 Finally found a link to Customer Service. Sent a message and got a response. Now, 7 hours later, still waiting for next response. Their online  support Service is offline.

[klsmurf]

Must be a mad rush and clogged their server

[oztules]

Harold.... different time zone perhaps for the online help. Winnie has a lot of happy fans, so it must work.

Bsafe, If I read you right, then you will have eva, your current cell, eva and nothing else?

Do a small test, but I think wax paper will let you get this combination... ie wax paper, eva, your cell, eva wax paper, all in a bag.

I havent tested for it, but that solder wick copper braid may do ok for your hinge material


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

[jaskiainen]

Hi,
Been following this super topic. And it did its job. Just got 40 6" x 1.5" 1W solar cells. Yesterday i got tabbing wire and flux pen.
Still waiting EVA to arrive. (Also forgot to order bus wire).
So, here i am with you guys. Want to try build my own panels.

This one is for learning and first lesson learned already:These cells ARE fragile .
I was hoping to get enough power out of it to use 172mm Papst DV6212/12T Fan/Blower 12V/12VDC/DC (170mm).
Given specs are:
Air Flow: 412 cfm
Noise: 69 dBA
Speed: 5500 rpm
Voltage: 12 Volt DC (8 to 13.5 Volt range)
Current: 2.33 amp
Wattage: 28 watt

Here is a link to it:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=120695215999&ssPageName=STRK:MEWAX:IT#ht_2393wt_874

I tried to find PAPST given specs to this but found nothing. Same size PAPST (6224) made blower i found with these specs:
Air Flow: 318 cfm
Noise: 63dBA
Speed: 4300 rpm
Voltage: 24V DC (16 to 28 Volt range)
Current: I=P/U =1.2A
Wattage: 40W


So I'm a little skeptic of those given numbers on ebay. It sounds too much airflow against Noise and Wattage compared
to this one i found on PAPST web page.
Still giving this one a go. This blower should be used for my solar air heater to get most out of it.

My question here is what you guys think? If my solar panel comes out ok is it enough to power up this blower?
And when i still have 39 WHOLE cells left should i use all of them in my panel? That would make about 19.5V , 39W panel.
Of course i have to exclude the diode voltage drop. or should i just use those left overs for having some fun?
I think i don't want the blower to run with all of its power mainly because of the noise.

Right now i'm waiting that blower to arrive and want to do some tests with it before i make my final decision.

Best regards jaskiainen

[ibdilbert]

So far what I have found is there is multiple textures of EVA.  One roll I have is fairly smooth, another slightly rough on one side, and a roll I got from Mars Rock is really course.   I can't make a panel for the life of me with the smooth stuff without getting bubbles in it, my theory is its sealing itself off and keeping positive pressure inside.  

The Mars Rock EVA (Rough on one side) actually works great, the best so far I'd say.     If you email them, they have just about anything you would want to build panels, including backsheets.  Shipping is a bit rough though.  

Maybe we should try to make a database of where we are getting our materials and the prices we are paying.

The last order of EVA I purchased from "Linda" marsrock808(AT)marsrock.com.cn, been ordering from her for years and I like how fast she communicates.
For cells, its been a while since I've ordered from them, but you can order directly from KPE factory at "Chris Oh" csoh(AT)kpesolar.com, but be ready to haggle.

@safe10 "I have a few flexible stainless steel solar cells (sorry no pictures) that are 2.1v and 3.5 amps, they are approximately 8"x10" ." - Do you remember where you got these cells at?    

[dave ames]

hi bsafe10,

i'm curious what those stainless backed cells are too?

we have tried a few things to obtain a clear non backed lamination. no luck with wax paper or freezer type paper. some progress using aluminum foil though. found if we peal the backing away before the final cure we can get a water clear finish. removing the foil can be tricky..kind of like removing thin foil from a warmed up then cooled down chocolate bar? ..mostly comes off in bits and pieces. gonna have to give some of that oven type spray a try?  "pam" spray.

3 cell 1.5v charger on 8 1/2 x 11" glass:




the fun starts after we are done..this uncovered cured eva is a smudge/finger print/dust magnet! i fear it will become dirty very quickly if used naked in the front of the cell. but i suspect that we may be able to coat the surface with a clear "fusion" type paint (krylon) for better protection. as we have tried some fusion blue paint on the back of uncovered eva with satisfaction.

may be able to find some thin plastic for the covering? need to test the heating profile to be sure it holds up to the process. same holds for any nylon we want to use..that stuff should be good for 400*f+ but how well the material "plays" when used together would need testing. please keep us posted as to how you get on.

the last bc i bought must have been lined with gold filled eva!


hi jaskiainen,

looks like some kind of shell game going on with the power ratings in those listings. have to believe the power requirements will be about the same for the 12v and 24v fans listed.... (40ish watts) the 28 watts may be the air moving power? not sure how they will behave..specs say locked rotor protected,  don't really know what that is but like the sound of it. were you hoping to run this direct? no battery? any controls at all?

we need to be aware of the temp rating with the plan ..only 50 or 75*c  depending on what cut sheet you read.

6 x 1.5" cells? that's an odd size. seems we can reasonably expect to get about 0.07watt per square inch (of silicon) for a battery system and 0.09w with matched loading or with electronic magic. so about 22 (real world) watts with a 36 cell module.

curious to hear how the motor testing goes, kindly keep us updated.

it's all good fun!
cheers, dave

[wpowokal]

I have 3 solar water heater panels with glass in tact if anyone in SW Western Australia would like to roll their own panels, they are yours for the taking or they are in the skip in a couple of weeks.

Allan

[Pebbles]

Hi everyone, Thanks for the series Oz :-)

A couple of questions,
How are you layering output , are you coming out just with bus wire, or leads, or terminals ? how are you layering the eva in this area ?
Thx
Pebbles