Part of the problem is the solar road is trying to solve contradictory goals. That's not to say the solar concept may fit certain niches--hell, our urban heat islands show there is spare solar energy waiting to be used.
The good--yes, there could be an application for solar roads. Roads are generally in open spaces. Mall parking lots are designed for 100 percent utilization for 15 days per year. That's a lot of open space.
The so-so--the glass panels (from a pavement perspective) are just a surface treatment. The bulk of the load support comes from the box culvert that will hold the water, internet, and cabling the system will need. I assume they want them manufactured off-site for modularity.
The bs--a)the whole system strives to be modular. A panel breaks, unscrew a couple bolts, and pop a new one in. A 20 ton bolder smashes into a road during a rock slide. Pop in 20 new cells! Well, what happens when the whole box culvert shatters? A few 100 lb solar cells aren't going to bridge the gaps in the road.
b) Water is the enemy of roads and electronics. Since the cells are not bonded to the base, there will be water infiltration. With water comes silt, clays, and sand. The panels will fault in very short order. The ride will be very rough. Unless they can come up with a way to reliably seal the joints between the solar cells.
