You'd need a rigid structure to keep the gyro from ripping itself loose from the structure. Even constructed as a giant space frame, that's a lot of mass to deal with the torsion of the structure rotating.
A structure 100m on a side would be just at the bounds of current technology (the ISS's control moment gyros). With 30% efficient panels that's only about 4MW before conversion and path losses.
The high impulse ion engines to desaturate the gyros would still need to be refueled regularly. I think you're hand waving a lot of complexity that even if completely solved still leaves a solution that's orders of magnitude costlier than solar panels on the ground.
