I lived in LA. It is a desert. It'd be just fine to cover parking lots, highways, and rooftops with solar. There are at least 100 square miles of parking lots in LA.

LA actually isn’t a desert, although there is desert in the LA area. Most of LA is classified as Mediterranean, and gets enough rain (the closer to the coast, the less deserty it is). Lots of mountains make for interesting climate zones.

Fine, to be pedantic, it's right on the limit of being desert. LA averages about 15 inches of rainfall per year, whereas the classification for desert is less than 10 inches. With the amount of irrigation in the area, this is not generally acknowledged. Funny, I used to have to hop over a giant puddle in the street every morning to catch the bus to UCLA because the sprinkler systems for someone's 4ft wide lawn were just that badly misconfigured. I always thought that inane.

I spent all my time in LA living in Westwood, and saw some interesting rain storms while I was there. Interesting tidbit: Santa Monica (just next to the coast) actually gets less rain a year than LA (13.5 inches vs. 14.7 inches). I'm guessing they get more moisture in fog than in rain.