It's companies trying to make a quick buck. They tried this with roads too.

Obviously every home should have them first and all newly built homes should be built with solar efficiency in mind.

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.

Or in parking lots. It would also have the added benefit of providing cover for cars.

Roofs are actually not that great. Installation is expensive because you are working at height. Roof angles and directions are also not ideal on many houses. Compare it to a simple installation on a field: You just take some corn field, stop growing corn there and can put your panels on some cheap holders and you're good. You can access and service them without the danger of falling from a roof. You can install them on an industrial scale instead of a few square meters on every single roof. You need only one electrical installation.

People love to cry about the loss of agricultural space, but currently we are growing a lot of corn to convert it to fuel or to put it into biogas installations. If you convert those field to solar, you will get more energy from them. And the loss of a big monoculture that is using a lot of pesticides is also great.

Hell parking lots are massive areas of dead space, build them over the damned things, it'll help against the heat island affect and give shade.

You can lay them down and remove them again and also clean them with automation. There are power lines nearby as well as consumers, electric trains.

Installing on roofs is manual labor and needs electricians. Which is why you see so many solar farms by the roadside.

I’m guessing this installation is an experiment to quantify these figures rather than a commitment to roll this out more broadly.

No need to guess, it's right there in the article.

air currents from trains, especially high speed ones throw rocks and debris everywhere.

Sometimes a body

ROI would take a lonnnnng time, in my view. It's the same idea as installing modules under asphalt roads or even above them. It's not really worth the O&M hassle whatsoever.

The same idea goes for installations like canals. They're linearly too so not the wisest use of modules. But the benefit of modules over water like that is lower rates of evaporation as the panels block the sun. Same is true for water department reservoirs that see lots of algae. The panels block the sun and choke out the algae.

But you're right about the shading. If these panels are installed in higher latitudes, then odds are they might never see the sun directly at certain times of the year. Usually solar designers only recommend flat horizontal mounting for modules in hurricane- or tropical storm-prone regions like near the tropics, or close to the Equator where the Sun shines directly overhead most of the year.

What I COULD see happening is if governments around the world start transitioning railroads to have H-frame structures that suspend feeder lines like what's used in electric trains with pantographs. If you set up those H-frames frequently enough, you have the underlying structure similar to carports and can install modules 4-10 modules wide. THEN you can utilize string inverters every 7-8 H-frames or so, converting the solar DC power into AC which can help feed the train loads as they pass or feed the grid.

Bonus of the above system is that over time, all trains including rail freighters become electric or at least hybrid to make use of the free power generated above them throughout the railway.

Lots of ideas!

I think the biggest limitations will be security, someone will definitely be trying to steal them