In the final state will be 60% of the maximal daily yield be the minimu battery capacity. But even at the begin of the solar duty will be an appropriate sized place for the storage a duty.
Not only for solar electric power
The storage is not only for the day/night balancing from solar electric power, but also for different tasks to optimize the electric power generation.
Avoidance to built new fossil power plants, because existing power plants can be better uses because of the batteries.
Impovement of the efficiency of fossil power plants by avoiding partial load and frequent load change.
Avoiding the provision of fossil electricity generation for wind energy prognosis failures.
Management as a virtual power plant
In the sense of the project combi power plant should all solar power plants with storage do the best for a secure and einvironment friendly electricity production.
Dimension of the battery room
For a one family house with 12 kW peak minimum photovoltaic requirement, 100 kWh maximal possible daily yield, the batteries place has to be enough for 60 kWh batteries. This is the order of magnitude like in a Venturi Fetish verbaut sind.
We assume 800 kg weight. So this battery place has to be able to store 750 kg batteries. 3m² should be enough.