Tabbing hints for solar cells

[elhifnawyplast]

Can anyone give me some tabbing hints for tabbing 36 6x6 solar cells minimizing the breaking of the cells,what type of solder is recommended,and why the solar cell concave when soldering.
any help will be appreciated

[TuffGirl Builder]

I'm new to tab soldering too. Maybe this may help

Check out first clip in the series for a better understanding. He uses the tempered glass under the cells to take some of the heat so that the cells don't warp from the heat. He also uses CL-Flux, he swears by it along with a dental pick. I found the flux on ebay for about $6 including s/h. I am actually using broken 3x5 cells in my first solar panel build. Good luck in your quest. I have been reading up on the solar energy specs etc for a while, but am finally getting the courage to try a build.

Mod note - youtube link removed

[elhifnawyplast]

Is it forbidden

I wanted to post some youtube videos to demonstrate what other do and discuss it but i do not know if it is forbidden ?

[russ]

I wanted to post some youtube videos to demonstrate what other do and discuss it but i do not know if it is forbidden ?

It is generally not allowed.

[inetdog]

I wanted to post some youtube videos to demonstrate what other do and discuss it but i do not know if it is forbidden ?

If you want to describe the video well enough that a YouTube search could easily find it, that would probably be acceptable. But putting a direct link to the video both gives it a higher reputation among the search engines and can make it too easy for people to think it is in some way endorsed by Solar Panel Talk.
There is so much that is absolutely crazy or outright fraudulent on YouTube that many clips from there are not even worth discussing.
A long time forum participant, and one who gives a good description and background of a clip will be given a little more leeway by the moderators.

[TuffGirl Builder]

Thanks for making us aware and explaining the reason for not allowing links of that nature. I think its a good idea for me to reread the rules etc of this forum as I wouldn't want to be kicked off for habitual violations.
With that being said, search specifically "How to build a solar panel" and you should find what you are looking for. Its in 3 parts. Thanks again for clarification!

[inetdog]

Thanks for making us aware and explaining the reason for not allowing links of that nature. I think its a good idea for me to reread the rules etc of this forum as I wouldn't want to be kicked off for habitual violations.
With that being said, search specifically "How to build a solar panel" and you should find what you are looking for. Its in 3 parts. Thanks again for clarification!

As far as the process and craftsmanship, the first one anyway looks like a well produced and useful video.
But there are a few problems that most people on this forum will immediately pick up on:

1. The economics of building your own panel have changed greatly since that video was made. A 60 watt DIY panel for $100 does not make sense in today's market where in larger sizes you can get a factory made panel with a 20 year warranty for under $1 per watt. The factory panel will (usually) be UL approved and can be used in a grid-tie or off grid system in a way that keeps the inspectors and insurance companies happy.
2. The statement about flux "just like a plumber would use" is dangerously oversimplified. Some plumbing flux is acid-based. It will do a great job of getting the oxide off heavy copper. But the residue will be electrically conductive if it gets damp and the corrosive effect can even eat through thin metal foil like tabbing wire eventually.
3. I know of no source of bulk bare cells that can give you the same quality cells that go into factory made panels. What you see on ebay and elsewhere are second or third grade cells for which there is no other market.

If you just read through the comments, you would not see anything about these issues. So even what look like really high quality videos can mislead you if you do not already have a background in what they demonstrate.

[elhifnawyplast]

to discuss the videos it self

I did not want to put the youtube links to show how tabbing is don but to discuss the videos it self ,is it don this way or is it better another way,and if we can get any tips out of it, specially that watching describes better than reading.
Any way dose anyone have good new tips for tabbing minimizing bracing and cracking,and what is the best soldering material

[Mike90250]

.....
Any way dose anyone have good new tips for tabbing minimizing bracing and cracking,and what is the best soldering material

the bast solder material is 63/37 old school electrical solder. It's a much lower melting point than the lead free solders, and has a bit of flex in it. Slow warm up and cooling, but solder as quick as you can to avoid dissolving the metal plating into the solder.

Clean before, and after, the factory agent is 99% IPA (isopropyl alcohol)

Good Luck

[elhifnawyplast]

soldering

the bast solder material is 63/37 old school electrical solder

what does this number 63/37 present in soldering ?

[elhifnawyplast]

reducing the cracking of cells

From some research i have don through the net about reducing the cracking of cells during tabbing,i learned that cracking of cells are due to thermal stresses and non proper handling of cells as they are very fragile, the lower temperature used for soldering better results are achieved but enough heat must be used to melt the solder.
Sn96Ag4 with a melting point of 221°C and bismuth containing Bi58Sn42 with a melting point of 138°C are recommended for tabbing solar cells.

[Mike90250]

what does this number 63/37 present in soldering ?

http://en.wikipedia.org/wiki/Solder

That's the ratio of Tin / Lead in the solder. 63/37 melts at 183 °C or 361.4 °F
Other solders are unproven in their longevity, they seem to mostly work ok in the lab testing.

[elhifnawyplast]

curvature which appears after weldingddd

Thanks for the explanation and clearing the terms used.
Another thing in welding is bothering me, the curvature which appears after welding the solar cells,should i put cold surface as tempered glass or granite under the cell to disperse heat coming from welding, or a lightly heated surface to compensate for the temperature difference,dose anyone have some experience.

[inetdog]

Thanks for the explanation and clearing the terms used.
Another thing in welding is bothering me, the curvature which appears after welding the solar cells,should i put cold surface as tempered glass or granite under the cell to disperse heat coming from welding, or a lightly heated surface to compensate for the temperature difference,dose anyone have some experience.

It is good that you are observing what happens when you solder and are asking questions!

There are two different mechanisms at work here:
The absolute temperature can damage the semiconductor and the coatings, and can even make the electrode separate from the surface of the cell. Starting with the cell cooler may help that a bit.
The difference in temperature from the top surface of the cell to the bottom can make it curve. This will not, by itself, cause problems unless the solder hardens while the the space between two solder points on the tabbing wire is different from what it will be when the cell cools. The best way to avoid this, I believe, is to solder the connections on a given piece of tabbing wire one at a time, letting the cell cool between joints.

But by far the most important things are to use low temperature solder and to use a clean iron, of the right temperature, properly handled, to keep the heating of the cell to a minimum.

(By the way, we call it welding when the two metals are actually melted to join them together. Using a different low melting point alloy (melting temperature similar to lead or lower) to join them is called soldering. Using a higher melting point metal (like brass) is called brazing.
Properly done, spot welding can make a joint between two metals, like on battery terminals, with even less heating than soldering because it happens so fast. But the metal coating on the cell and the tabbing wire are too thin to allow that to be used here.)

[green]

I found that using a small 40 Watt iron is hot enough without being to hot for tabbing. I also use a sheet of metal that was actually the side panel of an old PC under the cells helps dissapate the heat. Oh use the unpainted side if youre going to use a PC panel BTW, found that out the hard way of course. I also use a small computer fan (hooked directly to one of my small solar panels) pointed at my work to cool the cell and blow away the fumes from soldering.