For marine, it seems that cargo ships could have large solar arrays for energy regeneration I do not think there is any practical scenario where a vehicle can

For marine, it seems that cargo ships could have large solar arrays for energy regeneration I do not think there is any practical scenario where a vehicle can be self-solar powered for long distance journeys. The energy demand scales up with the size of the vehicle. This is why you don't see EV's with solar panels for primary power (I am aware of some like Fisker that have essentially novelty solar panels). A cargo ship loaded with solar panels would be highly impractical on a number of levels, and would not be able to gather enough energy to make it worthwhile without a massive increase in panel efficiency.