Oh of course, you'd need to coordinate the battery size and capacity with the robot's requirements. No need to overpower it. But it's the internal processor that'll require attention. If it's meant to have internal memory and rudimentary software to process details, that's what will cause the biggest power drain.

[Otto's already thinking ten steps ahead and wondering how the processor will work, but he realizes he should probably dial that down.]

Either way, if they require light to charge, they can easily get settled in the indoor garden beneath one of skylights. That way, they won't actually need to go outside for the most efficient charge. It's the same for the windows at the A Tower.