Trains in Switzerland Are Now Running Over Solar Panels in a First-of-Its-Kind Test
(www.zmescience.com)
Deployment on rails is dirty cheap. Can be highly automated and you have highvolt power line just a few meters away.
If you put solar upon your roof, 2/3 of the costs are labor costs. The material bill encompasses electrics, mounting system, cables, and pv panels that can get reduced on railways as well.