SMA SUNNY BOY STORAGE 3.8-US Instructions D'installation page 19

SMA Solar Technology AG
connected can be supplied by the battery and supplemented with energy from the PV system. The
charging of the battery is ensured by the existing PV system during battery-backup operation. The
charging process of the battery (initiated by the PV system) can be deactivated via a certain
parameter during battery-backup operation. 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 (information in terms of switching operations of the automatic transfer
switch and procedures during grid failure and grid reconnection see planning guidelines
"SMA FLEXIBLE STORAGE SYSTEM with Battery-Backup Function").
When the utility grid is down and the battery discharged, there is, in the beginning, not enough
power available to create a stable battery-backup grid. In this case, the battery must be charged by
the PV system. The battery inverter is able to create a stable battery-backup grid only when enough
power is available in the battery. To use battery charging power from the PV system, the battery
inverter has to create a stand-alone grid. For this purpose, the battery inverter requires energy from
the battery reserve. If enough PV power is available, the PV inverters start automatically and the
battery is charged with energy from the PV system. The battery is charged with energy until the
battery inverter is able to provide a battery-backup grid. The state of charge can be configured via
certain parameter. If not enough PV energy is available to start the PV inverters, the stand-alone
grid breaks down. Two hours later, the battery inverter tries to start the PV inverter again to charge
the battery with energy from the PV system. If the battery inverter still fails to create a stand-alone
grid after several attempts due to insufficient PV energy, the battery inverter and battery switch to
sleep mode. In this case, a manual black start is required to switch the battery inverter and battery
from sleep mode back to operation.
An updated list of automatic transfer switches approved by SMA Solar Technology AG is available
at www.SMA-Solar.com. You are not allowed to install automatic transfer switches for operation
with this inverter by yourself on the basis of a circuit diagram.
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.
Black start function
The inverter has a black start function and an auxiliary battery that provides energy for the black
start. In battery-backup systems, you have the possibility to install a standard switch for black
starting the inverter and battery. The black-start switch is used to start the battery-backup operation
manually in the event of grid failure if the battery and inverter are in sleep mode and, therefore, are
Installation Manual
4 Product Overview
SBSxx-US-10-IA-xx-12 19