Yeah people tend to overestimate the needs of solar power and underestimate the extent of America. Take for example California. It could very easily be powered by a PV installation about the size of Edwards Air Force Base, which is << 1% the extent of the state. Not every state is so lucky, but there are grids.

If you sacrificed 10% of Nevada, which history shows we are more than ready to do, that alone would quite easily power America.