This particular idea is an outstanding sample of spending budget on outrageous stuff. While every single engineer with a note paper and a pen predicted the inefficiency of Solar Highway, the eurocrats persisted to spend taxpayer money vigorously.
We've commercial solar energy facilities around the world, and we understand that they are still expensive compared to some other sources of energy. The solar panels are positioned to the Sun to attain better efficiency. These are usually washed regularly, get a lot of maintenance, and no one is going to ruin these with several tons of mass. That's the reason the solar highways will never be so profitable as solar powered energy stations. The solar highway cannot be aligned with the Sun, and it often will be shadowed by vehicles! It's so damn foreseeable!
One other ridiculous idea is to put technology in attempts to make the solar road able to stand the damage. The highway construction companies spent hundreds of years in cost efficiency optimization. Replacing the highway coat with expensive solar boards will likely ruin the ROI for each of them: the highway and solar energy project.
I have truly serious concerns about solar highways becoming a part of the nearby future. They could spend tons of euros and do countless research campaigns, and it still going to be in vain.
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