Absolutely the stupidest idea ever. A total triumph of marketing over common sense.
Because the panels have to be horizontal, and because they will get dirty and have to be load bearing, they have something like only 30% of the energy return of a conventional roof mounted (or other structure) set.
So, for any given capital outlay, they will only return 30% of the total energy over their life as a conventional set up. Then you get to the fact that they require a hugely costly preparation and installation (compared to normal panels you just stick on a pole) and are going to require more maintenance etc.
So, why in a CAPITALIST economy would you pay 3x more for something?
For example, if i said, either:
1) give me £100, and i’ll give you £10 in a years time
or
2) give me £100 and i’ll give you £30 in a a years time.
which one would you go for??