Germany has 50 million cars. Are you saying that after those have been turned eletric their batteries alone would be enough to cover the countrys battery needs?
Ergo the rise of concentrated solar thermal plants (CSPS) and using excess peak solar to produce hydrogen, ammonia, methonal, etc for off peak (night time) demand.
Batteries aren't the only way in which energy can be offset by 10 hours to meet lower night time demand.