Most desert ecosystems have a wretched excess of sunlight, and lack moisture.
Solar panels treat both of these: they capture a lot (but by no means all) of the sunlight, and serve as a nice, concentrated condensing surface for dews.
You can see this at a panel farm in dry areas: there's often a nice row of green in front of each panel, precisely where the condensing dew drips off them onto the ground below.
Deserts aren't necessarily things to be "treated." We definitely don't want the entire world to be a desert, and the growth of the Sahara is somewhat troubling because of what it signals, but saying they have a "wretched excess of sunlight" and are fit to be exploited by humanity is the same attitude that got us in our current energy predicament.
