Building renewable energy sources doesn't pay off at the moment, so nobody is interested in doing so. If that gets fixed, the amount of renewable energy sources will rise.
I'm looking at the same problem with my parents' house at the moment. Just putting some panels on the roof won't help with anything. You need a concept for the whole house and making that is just lots of work. If people could just spend X Euro and be sure to have the money back in 5 years because they can sell the electricity or whatever, lots of people would be in, I'm sure.