You can probably increase your self-sufficiency by a few percentage points without increasing the capacity of your battery size by installing a building control system. Here are a few ideas to consider:

1) change the washing machine use pattern from push to pull - always fill it up with dirty laundry, start it when there is sunshine

2) heat up the water boiler during daytime, increase the boiler temperature - because you have enough energy during the day, and as a counter-measure when you loose some temperature through the night

3) same thing with the charging of the cars

4) most modern building control systems offer a weather service to make tactical decisions based on the weather forecast

However, if you want to further increase self-sufficiency during the dark and cold months, there is no way around small-scale wind power and/or seasonal storage.