With the cost of solar panels still out of many peoples reach (including mine) homemade solar panels are a very cost effective alternative. There are only a few steps to building a solar panel. First, you need to connect individual cells into strings of cells. Each string consists of 6 cells and you need 6 strings to make a panel (for a total of 36 cells). Once you've made the strings of cells you need to connect all 6 strings together.
The reason you need to connect all these solar cells together is quite simple. Each cell only produces about 0.5 volts which isn't enough to charge anything. We hook them up in series (positive to negative) to increase the total voltage that the panel puts out. With 36 cells the panel will output around 19 volts which is enough to charge a 12 volt battery.
Iron Solder
To start with you're going to need to get all the materials and tools together. The materials you're going to need are the strings of cells, bus wire, solder, flux, and a piece of 2' x 4' of plexiglass, and some silicone (clear). The tools you're going to need are a soldering iron.
Start by peeling off the piece of paper on the plexiglass. Lay down the strings of cells and make sure they're all evenly spaced apart. I use a small piece of wood for this. When the string is where you want it put a couple dabs of silicone on it to tack it into place. Do this for all 6 strings.
After the silicone is dry you can now solder the strings together. Place flux on the end cells of each string. The flux is needed otherwise the solder will stick to your soldering iron instead of the cell. It also cleans the surface so it's a nice clean joint. Cut a piece of bus wire (basically tabbing wire, but bigger to handle more power). Solder the bus wires up so all the strings are connected together.
That's pretty much all there is to connecting strings of solar cells together for your homemade solar panel. Once I'm finished that I usually take off the front piece of paper off the plexiglass and test it with a multimeter to make sure it's producing power.