In a prior post by jacquesm, he stated....
-------------------------------------------------
solder copper to aluminum with standard irons and solder
- place aluminum to be soldered in a bath of mineral oil
- sand aluminum while immersed in oil along the surface to be soldered to remove the oxide layer present (re-oxidization which would normally happen in seconds will now not happen as long as you are immersed)
- Solder copper wire to aluminum while maintaining immersion. Don't use a torch or you will set the oil on fire ! Just a regular (but plenty hot) iron will do
- Remove soldered piece from oil, rinse and dry.
It's an old trick, and it really works, even if the joints aren't perfect they are good enough for most purposes. The problem with soldering aluminum is not so much in the metal its self as it is in the oxide layer on top.
-------------------------------------------------
Now since the back of the solar cells are a composite aluminum glass, I was trying as many of you where to solder to it. I tryied everything.. nothing worked proper, then I remembered that post and figured I would try it, guess what! I works!!
However there is a catch...
It does make a connection and does bond, but not deep...It is diffecult to do and sometimes will come off. The trick is the right temprature, rubbing the soldering iron slowly in a circle or across the surface untill it catchs. (basically sanding/soldering in oil) once it does and you play with it a little it's not to bad. It will completly adhear and cannot be removed.
That basically solves soldering the back part of wireing the cell at any point on the cell. The stuff is aluminum. It is neat how they came up with a flux/material pad to solder to and adhears to the back of the cell. very neat..