[thomasmg]

My guess is: the problem is not the price of the land or the price of the structure, but the permits. In Switzerland, you can put solar panels on existing buildings without requiring a permit.

As the article says, there are many "large" solar panel projects planned in Switzerland, specially in the mountains, where the snow will reflect the light and increase electricity production in winter (where electricity is the most expensive). But it takes a very long time (sometimes many, many years) until those projects are approved, if they are approved at all. This is known to be a problem, and government did try to speed this up, but it still is far too slow. (I'm Swiss.)