Even if all costs where exactly the same as those of a conventional road (probably not the case by a huge multiplier) maintenance costs would be massive. A con

Even if all costs where exactly the same as those of a conventional road (probably not the case by a huge multiplier) maintenance costs would be massive. A conventional road can be full of dirt, scratches, dings, holes, cracks, bubble gum, etc. and still be perfectly good. Just looking outside my home right now I see that our street is probably covered about 25% in shade from the trees and homes on both sides. The next issue is that in most developed countries you would have to first destroy a road before installing solar modules. I can't even guess at the cost of doing that, even if you recycle the materials. Remember that all of these activities have an environmental cost in burning petroleum. The trucks and equipment doing all the work and moving the materials and waste are burning fossil fuels. Even a hamburger has a petroleum cost factor due to transportation and manufacturing steps. Is it a good idea for less developed countries where there might be no road? No, it's a horrible idea. The last thing those countries need are high-tech roads with 3x the installation cost and 1000x the maintenance cost.