Solaredge Backup Interface Wiring Diagram. Basically that is 1500w * 12 = 18000wh. Diagram below, on the left.

Looking at the wiring schematic on the inside of the enclosure door on one of their pictures, it doesn't seem like that device has any significant differences over the solaredge transformer. 1 switch 2 battery 3 resistor and 4 ground. Each part ought to be placed and linked to different parts in particular manner.