Hey madepablo, I think I might be able to help.
We do Open Source Hardware at Rachel's Electronics, and are going to be introducing the new SolArduino at World Maker Faire here in New York this weekend. We'll be selling a limited number of kitted prototypes for early adopters at the Faire. I'm holding back to post a new thread about it here until tomorrow, because I will get the prototypes from barebones in the morning and want to have pictures of the first populated SolArduino 
This inital prototype was designed around low power remote sensing applications, but with the right battery/panel combination, we feel that robots are not far off.
In the mean time, I have lots of documentation of the circuits and process at Rachel's blog. Link below.