>Because when the government goes and says "I need 40 million acres of solar panels"... Who is going to do that? Where is that going to come from?

1) the empty arid land where we would put 40 million acres of solar panels is for the most part already owned by a state or national level government. go look at a map of how much of nevada is controlled by the BLM for instance.

2) governments already pay for electrical generation through nuclear power plants, building hydroelectric dams, etc. the question would be to apply that same money to building giant ground mount PV instead.