Solar Highways-Interesting Idea

I don't see that working,to many easily accessible roofs to utilize before putting solar panels on roads. Im trying to convince my mom to have some installed before I enlist. They pay for themselves in about 3 years,so I see no reason why people haven't done it already,and I'm by far no tree hugger but why WOULDN'T you want to end you electric bill? And it's not like the stuff isn't getting cheaper every day,there's already solar PAINT and solar chips that are printed and cost very little,so well just have to see what happens after gas hits 20$ a gallon and the energy crisis REALLY heats up.