While each and every single engineer who may have a piece of paper and a pen predicted the ineffectiveness of Solar Road, the eurocrats vigorously continued to spend taxpayer money. This venture is a good sample of throwing away tax money on outrageous stuff.
We've commercial installations of solar cells all over the world, and we understand that they are still expensive when compared with some other sources of energy. The solar arrays are aligned with the Sun to attain better efficiency. These are usually cleaned regularly, get a lot of maintenance, and nobody is going to destroy any of them with several tons of mass. That's why the solar roads will never be so efficient as solar powered energy stations. The solar road may not be aligned with the Sun, and it constantly will be shadowed by cars! That's so damn predictable!
Yet another dumb plan is to use technology in attempts to make the solar highway able to resist the damage. The roadway engineering industry took centuries in cost efficiency optimization. Upgrading the road coat with pricey solar boards can ruin the efficiency of each of them: the road and solar energy project.
I don't believe that these types of solar roads are going to be a part of the nearest future. Regardless of what amount of money is going to be invested in scientific studies and how many coffees cups the designers will probably drink.