Most installation delays are not caused by the equipment. They are caused by a site that is not ready. A handful of preparations made in advance can cut installation time substantially.
Start with the floor. Systems of 500 kWh and above weigh several tonnes, so they need a level concrete slab rated for the load. Next come the clearances around the enclosure for maintenance access, and the route for moving equipment into position. Containerized systems also need crane access and a prepared pad for a 20 ft or 40 ft container.
On the electrical side, define the tie-in point and reserve space in the main switchboard ahead of time, along with the routing for the monitoring communication cables (CAN / RS485 / Ethernet). Finally, safety: check clearances from fire escapes and combustible materials against your building code.