Also, costing €623,000 over three years sounds rather expensive for just 100m

It's hugely expensive, but I expect most of the cost to be in the wagon that lays panels down and picks them up - and could hopefully service a big stretch of railway (if it works). That kind of systems will cost a pretty big penny.

I doubt if this project will "fly", however. A totally horizontal solar panel at ground level is a far cry from producing energy efficiently.