SMA SUNNY BOY 3.8-US Instructions D'installation page 18

4 Product Overview
During active secure power supply operation, the inverter is disconnected from the electricity and
does not therefore feed into the utility grid. During secure power supply operation, the load can
only be supplied with energy as long as there is stored energy available in the battery. If there is
insufficient energy available from the battery, the secure power supply operation remains active,
even if the utility grid is available again. Switching over to supplying the load from the utility grid
does not take place automatically. Once the battery is sufficiently charged again and the load can
be supplied, the secure power supply operation must be restarted.
Secure power supply operation in Flexible Storage Systems with backup
power supply not possible
If the inverter is used in a battery-backup system and connected with an automatic transfer
switch, the secure power supply operation is not available.
Do not connect any loads that require a stable energy supply
The secure power supply operation and the battery-backup operation may not be used for
loads that require a stable energy supply. The energy that is available during the secure
power supply operation or battery-backup operation depends on the battery capacity
available and the state of charge of the battery (SOC).
• Do not connect loads if they are dependent on a stable energy supply for reliable
operation.
Battery-backup function
The inverter is equipped with a battery-backup function. The battery-backup function is deactivated
by default and must be activated via the user interface. The battery-backup function can only be
activated if the inverter is operated in a battery-backup system with an automatic transfer switch.
The battery-backup function ensures that the inverter forms a battery-backup grid that uses energy
from the battery and the PV system to supply the household grid in the event of a utility grid failure.
When the battery-backup operation is activated, the automatic transfer switch disconnects the PV
system and the household grid from the utility grid in the event of a grid failure, and connects these
to the battery-backup grid. After a short switch-over time, the battery-backup grid and loads
connected can be supplied by the battery and supplemented with energy from the PV system. The
loading of the battery is ensured by the existing PV system. As soon as the utility grid is available
again, the battery-backup operation is deactivated automatically and the loads are supplied with
energy from the utility grid. If the automatic battery-backup operation is not set, the battery-backup
operation must be manually activated in the event of a grid failure, and must also be deactivated
again once the utility grid is available.
An updated list of automatic transfer switches approved by SMA is available at www.SMA-
Solar.com.
Secure power supply operation in Flexible Storage Systems with backup
power supply not possible
If the inverter is used in a battery-backup system and connected with an automatic transfer
switch, the secure power supply operation is not available.
18 SBSxx-US-10-IA-xx-11
SMA Solar Technology America LLC
Installation Manual