First, power grid cost are outrageous....more than most all EU member states. If you were talking about 15 days a year of running a AC unit....it's not bad. If this were 60-odd days....some folks would have a cash-flow problem.
Second, if you live in a apartment building built in the 1950s/1960s/1970s, and hasn't had a electrical renovation....you probably have a limited amount of power that you can draw. You could overcome the issue....with a 3k to 5k project.
Third and final....there's a guilt 'trip' involved....where public TV (ARD/ZDF) will attempt to identify you as a problem. I would imagine a quarter of the population would prefer not to receive criticism.
