Climate differs wildly throughout Germany. Berlin tends to get hot days, but those are of a moderate number. The upper Rhine valley where I come from has a warmer climate, but less extreme summer heat (lots of forest area around). The coastal area is generally cooler during the summer.

So yes, we do get hot days, but it's still rare that people have air conditioning in their flats. Modern office buildings have air conditioning though and most shops as well. Still, when the temperature difference is lower you still need less energy to power them. Another point is that it's a rare occurrence to have no sun (hence no solar power) and massive heat.