Here in Germany we have up to three months of almost zero solar production in winter due to foggy conditions (measured from my own solar inverter). It is not feasible to store summer electricity until winter in batteries. Batteries have self-discharge and would be hilariously expensive per KWh if they only cycle once a year. Chemical storage is probably the way to go here at least, and hydrogen can be used for many other useful things than just heating or running power plants.

Although there are many sunny countries where solar + one or two days of battery storage are probably enough for the full year.