Government decided in its infinite wisdom many years ago that solar installations needed a subsidy to flourish. Since government has a crystal ball, it knows exactly how much subsidy is needed and for how long.

The linked article talks about an expansion of capacity as the government subsidy ends? Do you think that, in this case, the subsidy was unnecessary? https://finance.yahoo.com/news/german-solar-battery-maker-sonnen-093232731.html