Solar Cell Wax Removal

[wayne]

Hi

I got a bunch of 6 by 3 solar cells and they shipped them sealed in wax, to avoid breakage. They say to put box in hot water, and keep doing until all wax is gone. Well after many times I still see wax on cells. I did get some unwaxed ones, nice and clean and easy to solder, but these waxed ones are a night mare. How do solar places ship cells? Do I keep washing them in hot water, seems the more I play I get more breakage. Any had this problem.

Thanks

Wayne

[TomW]

wayne;

Those things are as fragile as potato chips. If I had your problem I would simply hang them from a clip beside my wood stove with a newspaper on the floor, let the heat gently melt it off. Very little handling and no water contamination. or lay on a grate or screen do the same.

No wood stove? Then in a slow oven say 250 F

Just what I would do.

Cheers.

TomW

[fungus]

I think I remember seeing that you can clean them in thinned solvent to take the wax off but dont take my word for it. Otherwise I'd do what tom said.

[wayne]

Tom

I did try this in a oven at 175 using a steel pan and mounted them vertical and little sticks on bottom of pan, so they would drip. It worked better but still have a thin layer on cells. Also worried about cooking them to long, they seemed very hot. If they bring these boxes of silicon in how are they protected, seems this wax thing is not right?

Thks

Wayne

[TomW]

Wayne;

After the bulk of the wax is off you could probably use a mister and alcohol or maybe ether to clean them down to the cells. No idea how it would affect the cells so test anything you do first on one to be sure it doesn't damage it.

A lot of "wax" is petro based these days so seems alcohol, brake cleaner or ether would dissolve the thin layer. Just common stuff that will likely melt "wax". Of course test before committing them all and use plenty of ventilation.

Good luck.

Cheers.

TomW

[Nando]

Place them flat on paper towel and heat them for the wax to be absorbed by the paper, both faces.

Then Alcohol ( warm), dip them for a couple of hours and if you can stir the alcohol better.

Place them vertical and with HOT ( 130 to 140 F) Alcohol wash them for the was to flush away.

Lastly, it should be the first step, ask the manufacturer how to remove the wax.

Nando

[wayne]

Thanks Nando

Would this be rubbing alcohol? I will try the paper towel tonight. I got these on ebay and the guy said just hot wash them 6 times or so. Now I don't think a manufacturer would ever do this, think of workers with hot buckets of water, to funny!

wayne

[Gordy]

I don't remember the name of it, but I remember see some stuff in Wal-Mart that would desolve spilled candle wax from carpeting and whatnot.

Gordy

[Waterlogged]

Maybe try an auto body repair shop, or supplier. They use a wax and grease remover before painting. Of course test it on one cell first.

Rod

[wayne]

I did try paper towels on a few test and seems to work well, but still has a thin wax layer, I warmed up some rubbing alcohol and didn't really see the layer come off. Having a wax on makes soldering very hard and with lots off liquid flux. I would not recommend nobody to buy wax cells, its alot of work and haven't even built to panel yet. Somtimes wonder why me, I don't think I will seal these up as can see problems later.

Wayne

[stephent]

Use ammonia for stripping wax...test on a busted cell first of course.

Same thing like commercial floor wax stripper major ingredient.

[craig110]

Sad to say, I've come to the same conclusion.  The effort required to get the wax off without also ripping off the delicate solder tabs just wasn't worth it for me.  Since the manufacturer is only about an hour's drive away from my home, I even contacted them to see if I could buy the seconds without them being encased in wax (I pick them up, any breakage on the way home is my problem, etc.) but it didn't work out.

I had followed the standard directions of putting the block into a pot, covering it with water and heating it on the stove.  That worked well for getting the majority of the wax melted, but I ran into problems trying to separate the cells and lifting them out out of the near-boiling water one at a time without disturbing the solder tabs.  Plus, of course, the melted wax floats so while I could skim off the majority, there was always a little bit of melted wax that would happily restick to a cell being lifted through the surface...  If I was to ever try this again, I'd reject the near-boiling water approach.  What I'd do is put the block in the stove, leads side up, elevated a bit so that the melting wax drops away from the block.  Instead of trying to separate the cells while they are hot, I'd let the block cool off.  At this point, the cells should still be stuck together which would hold the leads onto the cells tightly but the external part of the leads should be wax-free.  I would then (gently!) straighten the leads as much as possible so they won't be tangled when the cells separate and then put the entire block, external leads pointing up again, into a solvent to dissolve the wax between the cells.  I don't suggest that this would make the dewaxing easy, but I believe it would be easier than the near-boiling water technique.

 

[wayne]

Sounds like you are having fun too cooking silicon. I tried placing brown paper on top of floating hot water, and hoping the floating hot wax would go, when I took out cells, put always a layer. And did this in oven with white paper towels face down and cook, seemed much better.

But here is I new one as I was told, get a heat gun and slowly heat the cell, then take a Soaked Rag with Windex, as you see the wax melt, wipe very carefull the cell with wet rag, if you happen to break you can glue together. Try this and I will tonight. Then come the problem is how well the solder will bond to tabs, I found it took lots of liquid flux and makes sure you retin the leads again and clean them. Let me know and good luck.

Wayne

[craig110]

In my case it is "had fun," past tense, not "having fun."  I got the DIY-panel bug this past summer.  After a while, I got fed up with fighting wax and bought commercial panels.  Since I was shooting for around 2Kw of panels, fighting to dewax each couple of watt cell just wasn't a winner.

[andyman5002]

I too bought some cells last year to make a panel, still haven't finished removing the wax. Its just too hard, takes probably half an hour or more per cell. The way I did it was using hot water like the seller said and used turps to remove the wax, not sure what this did to the cells. With the turps I applied it to a rag, soaked the cell, then very very gently scrubbed each cell. Then once i was happy that the wax was off I had to polish each one to remove the oily film. You can imagine how long it took, trying not to break any and so on. Surprisingly I only broke a few, the main problem with was with the hot water. The tabs kept lifting off, which was very annoying. Ive got about just over half a panel cleaned ready to use, but now as they have been sat around for a few months there full of dust. Ive just not had any time to spend on them, hopefully this summer I will finish my panel and turbine .

Andy

[DanG]

The vendor mis-specified the wax they used to protect the cells in shipping - candle wax is formulated with high melting temperatures to make longer burning candles. All the wax vendor designed their product for was to become liquid in a double boiler. There is soy-based waxes that melt at 135° (and up) that are used in cosmetics as well as candles, it is the vendors inexperience that is causing you grief.

The wax residue may not be all that bad; a non-corrosive soldering aide is required for the back plane solder where even the standard electronics rosin core type may be too active when viewed over 5 or 10 years. Mineral oil may work best, a drop on solder tabs will dilute the wax to help keep carbonizing down. Using the lowest wattage solder gun and solder is a good idea too.

Why try and strip all the wax off?  Once panels get heated a few times in full sunshine  perhaps the wax will have spread into an even protective film and also become transparent. A lower temperature wax certainly will, plus any wax film will help provide anti-corrosion protection to a degree against water condensation damaging the front plane collector stenciling and ribbon conductors...

[DanG]

heck  for that matter why not just encapsulate the strings between face cover glass and back cover with low-temp wax?

Have the cells spring biased (open-cell foam?) to rest against the face glass so the wax is thin as possible, then employ the suns' heat to melt wax into the clear liquid form. Perhaps the losses are severe when wax is a solid translucent state, but minimizing the thickness to sub-mm might allow acceptable losses.

If needed the panels could be drained down and replenished every few years, if the wax clouds up or something.

Anyhow - just musings

[wayne]

I tried the heat gun and wet windex rag and it does work, but takes alot of time believe me. And you break some too. But still not like the finish of an unwaxed cell. So with 144 cells its going to take awhile, once it gets sunny going to test open voltage, current with waxed vs un-waxed. Just to see if any damage is done to silicon.

Also tried putting into large bucket with hot water, thin wax comes to top, then put in freezer, and theory take hard wax off top, well it didn't work, seemed wax was at bottom!

Also paint thinner seems to work well on wax, but not to sure about silicon. I think soldering will be the easy part!

All for fun for a sick mind!

wayne

[RP]

The silicon and the metal interconnects will not care about organic solvents.  The only thing that could possibly damage either is the acids or caustics (like dishwasher soap or lye).