The scale is based on two things - storage capacity, and power capacity. Storage is the kwh of storage, which will determine how long you can run off-grid. The power capacity is the peak output power of the system when off-grid, and is usually limited by the inverters.

I am using the Enphase Encharge system, in which each battery unit also includes grid-creation capable micro-inverters. They are integrated into the same boxes, and can provide both grid offset, or grid generation. There is also a 'smart switch' that does the interconnects to the grid, and provides the autotransformer capability ( needed to have 120V split phase ).

There are some more details in my house/shop build thread on garage journal: https://www.garagejournal.com/forum/threads/jeffs-mountain-s...