You are right - solar panels are the most efficient tilted at an angle, that's why putting solar on rooftops makes so much sense! In fact, in 2019 we're working with Georgia Power to install a one-megawatt solar array in one of The Ray's diamond interchanges.
The solar road is not a question of either/or. The Wattway proves that the road can do more than provide a surface for vehicles to get from point A to point B; it can generate energy. Our transportation system is being smarter every year and will demand more energy. Some of that increased demand could be met by clean, renewable energy generated on the road itself. Our 50 square meter demonstration project generates, in one year, approximately the equivalent energy to the average American home's electricity use in the same time frame.