When building homemade solar panels one of the first steps is preparing the tabbing wire. First, just in case you're a little hazy about what tabbing wire is here's a little refresher.
Tabbing wire is just like regular wire except for a few key differences. The first major difference is the fact that it's not copper based. It's usually a mix of tin and other metals. This makes it conduct electricity a lot more efficiently. The other big difference is the fact that tabbing wire is flat. The reason for this is it has to be flat so it can be attached to each of the solar cells.
Iron Solder
Now that we've had a small refresher lets talk about how to prepare it for tabbing your solar cells. The first step is to cut your wire into the appropriate lengths. What you need to do to find the right length is lay two solar solar cells down with about ½" separating them. Each piece of tabbing wire should be this long.
I used to go through and cut each individual piece of tabbing wire by hand, but that was too time consuming. What I do now is take a small piece of thin wood and cut it to that length. Than you wrap the tabbing wire around that piece of wood. Cut the ends with a pair of tin snips and you've got all your tabbing wire cut to the perfect length.
Now that your wire is cut to the correct length you can move on to the next step in preparation. You need to do what's called 'tinning'. Basically this is applying a small amount of solder to half of each wire.
You only need to tin half of each wire because only half of it is soldered to the face of each cell. Here's what you do: first lay the wire face down and apply a little bit of solder to your soldering iron (a chisel tip works the best). Next, move the soldering iron down the wire to the end. This should leave a nice coating of solder on the wire.
The key point to remember here is to not use too much solder. All you need is just enough to get the wire coated and that's it. If you use too much solder you'll have a hard time attaching it to the face of each cell.
Now that you're tabbing wire is prepared you can move on to the rest of the steps required to build a solar panel.