Three routes
Small sites: high-voltage batteries with three-phase hybrid inverters.
Mid-sized sites: battery cabinets with their own power conversion system (PCS), scalable in parallel.
Large sites and grid services: utility-scale battery systems.
What to prepare
A year of interval load data (15-minute values if you have them), the grid connection capacity, the loads that need backup, and the space available for cabinets or containers. With these, the first quotation is close to the final one.
Site rules
Fire-safety, distance and ventilation rules for battery installations differ between EU countries and sometimes between regions. Your installer and local authority confirm what applies.