If you're building new structures I'm positive that the economics work out better for simply doing separate solar farms. Building them above a road has no major

If you're building new structures I'm positive that the economics work out better for simply doing separate solar farms. Building them above a road has no major advantages and potentially both increases construction costs and increases the chances of unfortunate interaction (eg an accident taking out panels). The sweet spot for solar roads would be in places where the generation benefit outweighed the extra cost when a road was being redone anyway - and even then only if the materials were up to the task.