Seems like you could put the same area of solar cells on short poles along suitable bits of RR right-of-way, slanted at the optimal angle for the sun, and get considerably more watts.

At a much lower cost. Those between-the-rails cells have to be far tougher - think about the dynamic mechanical loads they could face in winter, when the RR ran a snowplow down the tracks.

Are the cells themselves tougher, or do they just depend on the frame to keep them safe? Just navel gazing, but I wouldn't be surprised if these had better ROI- for conventional solar installations, the mounting hardware can be significantly more expensive than the panels themselves. And you have to worry a lot more about things like wind. Off ground would have better performance in winter, but shorter days in winter are going to be lower outut regardless

Also less grease dripping down on them, less water pooling on the flat surface...

My first thought was the sound barriers along the tracks and highways. A bit too small surface area and angles but looks like the panels are quite effective nowadays so with a some form of kinetic/hydro battery you can have an almost free lighting along the road for a useful life of the panels.