> flat terrain is just so much more practical.

Outside of peak summer it's much more optimal to have a south facing slope actually.

Additionally, solar panels can become too hot and that reduces their efficiency. Also, deserts are famously known for dust. Since it rarely rains, you get a dust buildup, further compromising solar efficiency in deserts.

I'm not saying that deserts are a bad place for solar. What I'm trying to say is - it's often worse than people think and it requires special infrastructure.