I read an article a while ago that threw some cold water on this idea. I don't remember all the particulars and was unable to find the link, but it went something like this.
The solar roadways people have tested the panels against traffic, and only traffic. What about sudden, piercing impacts, or any other impact for that matter? There's a difference between a car driving over the panel and a semi flipping and smashing down onto it.
The panels will inevitably become dirty, presumably limiting their ability to capture sunlight. The solar roadways people have proposed to use self-cleaning materials in or on the panels, but self-cleaning materials tend to be very slippery. Needless to say this could cause some issues.
Then, of course, the cost. The solar roadways people raised ~2 million USD on indiegogo or something, sounds pretty good. Except the total bill for all of this is estimated at something like 55 trillion USD, or 3-4 times the current US national debt. With the 2 million they have, the solar roadways people are hiring engineers and doing studies. Even if all of these issues can be overcome, we're a loooooooong way from wide-spread adoption.
I'm not trying to shoot down this idea, I'm in favor of stuff like this, I just don't know if it's feasible in its current form. I would encourage people to look up more information about the entire project, especially since I couldn't find what I was looking for. There's a lot of hurdles, but this could be really cool.
"My life has a superb cast but I can't figure out the plot." - Ashleigh Brilliant