It would be a neat trick if it could work. I suspect though that UV degradation of the plastic would reduce millions of square miles of it to rubble, and a lot of problems with water and salt intrusion.
Catching that degradation and replacement before the voltaic cells are damaged would be a very intensive effort in my opinion.
Still, it is thinking that’s definitely outside of the box. I’ll give the couple that.
Thinking out side of the box is what Solyndra did. Sometimes it is important to understand the science behind what you are doing before deciding that you have the answer.
Yes UV degradation is a problem but it is not the only problem...The voltaic cells are not going to see any appreciable amount of ‘sunlight’ (energy) at all. The plastic is going to absorb somewhere around 90% of the incoming (hence the degradation of which you speak).
I agree with your maintenance concerns. Roads and lots are very expensive to maintain over time with the technologies that we currently have. As of about 5 years ago, Germany dialed in the correct ROI ratio considering highway maintenance. Winter’s kill roads more than traffic, especially asphalt. Concrete is far more resilient but also more expensive. Moving toward this technology would be EXTREMELY expensive to install and I would guess more so to maintain. As in all things with “alternative” energy, an honest ROI would suggest this is many years ahead of practicality, regardless of how much energy could be produced.
Since we are talking about innovative concepts... Embedding small electromagnets and circuitry in concrete roadways could also be used to produce energy. The passing cars could be used by the system to produce some electrical current. But in this case, you would be stealing some of the energy from moving automobiles (assuming they are built of metal).