Possible photovoltaic power source

For my robot to be able to freely walk around my back yard, it is going to need a means of generating power while still resembling a tortoise.  One method I have pondered with is to use a small battery bank charged by an array of photovoltaic modules.  In order to begin learning more about solar power and develop a plan for how to possibly integrate solar cells into my robotic tortoise, I ordered a small panel from Newark electronics for $9. 

The panel is essentially a series of interconnected wafers glued to the back of a piece of glass.  Though the glass and glue help protect the fragile wafers from moisture and wear, they ara a little heavy and could pose a problem for a light weight robot

The back of the panel has two contacts.  Regardless of whether or not I am able to use this particular product in my robot, it should be able to help me make some informed decisions about what I will eventually chose to use.