[baldawar]

My best guess would be that this to test if solar works at all on roads. There were talks of this being really useful on Highway at non-peak hours.

If you end up setting Solar Farms, you're grabbing land from Nature. This way you can re-purpose the land already used (roads, footpaths, Highways) for more than moving person from point A to point B.

Also, it allows roads to be productive even when there's no traffic.