I'll bite: the US dedicates about 5 billion bushels of corn a year to ethanol production [0], which is basically solar with extra steps. At a generous yield of 190 bushels/acre [1], this is 26 million acres dedicated to ethanol production (WRI puts it at 30m [2]).

Depending on who you ask, it would take somewhere between 2.5 [3] and 13.5 million acres [4] of solar to supply total US electricity demand, including storage and maintenance etc. We could double it to be safe and account for the reduction in ethanol production, and it would still all fit within the land currently used for corn ethanol. (btw this works out to a >10x increase in efficiency over ethanol.)

Of course I do agree that there's lots of less productive land (desert in the west, grazing land in the plains, and parking lots/rooftops everywhere) that should be used when available. But even in the midwest and east the land use is not a problem.

[0] - https://www.ers.usda.gov/publications/pub-details?pubid=1057...

[1] - https://www.ncga.com/stay-informed/media/the-corn-economy/ar...

[2] - https://www.wri.org/insights/increased-biofuel-production-im...

[3] - https://blogs.ucl.ac.uk/energy/2015/05/21/fact-checking-elon...

[4] (PDF) - https://docs.nrel.gov/docs/fy08osti/42463.pdf

that ethanol leaves leftovers that are used for other things so your numbers are misleading.