I edited my comment and added a screenshot from my grafana dashboard to show the trend over the year and some other numbers. Batteries are expensive but they are worth imo. ~75% of the electricity usage of this house with 6 people comes from its own solar production. There is however a cut off for how much battery capacity makes sense. To get the last 20% of self sufficiency you would need a disproportionally larger battery to make up for long periods of low sun. so 80% is as good as its gonna get while staying cost effective.
For a house of 6 people we installed 5kWh which is basically perfect for them, but they are also very resourceful with their electricity usage, running washing, cleaning and cooking during the day as to not drain the battery at night.
But yeah if you dont get enough sun in your area its just a waste of money. My parents system will be payed off after 11 years if the sun stays at the level it has been at for the past 2 years.
Predicting how import vs export costs might develop is also a big factor