Where to solder on a solar cell

[rjgoebel]

I am working on a home project to build a temperature controlled, solar powered, fan for a rabbit hutch at a friend's house. I went to radio shack to just buy one solar cell to mess around with and familiarize myself with the things. I am looking forward to getting a better set of them so I can look at the documentation more, (the only thing available for the radio shack one is what is on the back of the box). It has vague arrows pointing to where I will need to solder on the cell, but I wanted to get a better feel for how these things work. Where is the cathode, where is the anode? Anyone care to explain the physics of solar cells?

Thank you!