Why solar powered?
Seems RTG would be a more sensible choice. Power where there's no sunlight. Guaranteed heat where it's really cold, no batteries to be killed by the cold. Move around only to fullfil the mission, no need to mooch off for a recharge.
I can only imagine the design meetings that led to this decision...
It'll operate in permanently shadowed regions of a crater at the Lunar south pole.
I know! Let's make is solar powered!
It's one of the coldest places in the Solar System.
Another winning case for solar power! Batteries love the cold, and their electicity can run heaters!
We need to efficiently map an area of the surface and subsurface.
Let's make it have to constantly trundle to somewhere there's a tiny bit of sunlight to charge the batteries! It'll never get too far away and risk running out of power before it can get back to it's charging point.