"As far as roads go, here's an opportunity to leverage a massive area of square footage that is guaranteed to be clear of plants or other obstructions"
Uh...no, it's actually guaranteed to be obstructed frequently, by cars, leaves, snow and ice (the suggestion of melting these away is absurd, there's nowhere near enough power for it), dust and dirt, machine grime, nearby trees, its own textured surface, etc. In addition, with all the stuff embedded in them and the enormous quantity of modules needed, things are going to break frequently, and maintenance access requires shutting down roads. Beneath the road surface is a *terrible* place for solar panels.