SMA S Technical Description page 78

Electrical Connection of the Automatic Switch Box S
Installation instructions
Do not install a galvanic connection (bridge) between the N conductors of the X2/PV
System connections and the X4/Backup Loads. If this is done the Sunny Backup System S
will not be able to start.
78 SBU2200-TEN083320
SMA Solar Technology AG
Technical Description