NREL estimates that a solar installation of about 100 square miles would power the entire US (3,809,525 square miles).

And as the following article indicates, that would still be less than the area we currently devote to mining and gathering and producing coal, oil, and gas.

Regardless, agrivoltaics is an interesting use case, as are the experiments in CA with using solar over canals and waterways in order to reduce evaporation.

Then there's also bifacial solar cells which can be used for fences and the like, once more reducing the footprint needed.

https://blog.ucsusa.org/steve-clemmer/how-much-land-would-it-require-to-get-most-of-our-electricity-from-wind-and-solar/