Supplementary Information; Determining The Battery Capacity - SMA SUNNY ISLAND 4.4M Operating Manual

8 Operation
In order to access SMA inverters with SMA Modbus
interface, the communication ports of the IP protocol can be changed. For information on commissioning and
configuration of the Modbus interface, see the technical information "SMA Modbus® Interface" at www.SMA-
Solar.com.
Measures for data security during activated Modbus interface
If you activate the Modbus interface, there is a risk that unauthorized users may access and manipulate the data
or devices in your PV system.
To ensure data security, take appropriate protective measures such as:
• Set up a firewall.
• Close unnecessary network ports.
• Only enable remote access via VPN tunnel.
• Do not set up port forwarding at the communication port in use.
• In order to deactivate the Modbus interface, reset the inverter to the default settings or deactivate the
activated parameter again.
Deactivate the dynamic active power limitation for the PV inverters when controlled via
Modbus
If the PV inverters and the battery inverter are controlled in a PV system via Modbus, the dynamic active power
limitation of the PV inverters must be deactivated.
Procedure:
• Activate the Modbus interface and adjust the communication ports if necessary (see the technical information
"SMA Modbus® Interface" at www.SMA-Solar.com).
8.12

Supplementary Information

8.12.1 Determining the Battery Capacity

Manufacturers state the battery capacity depending on the discharge time. In the installation assistant and in
parameter Rated battery capacity, always specify the battery capacity for a 10-hour electric discharge (C10).
Battery capacity C10 depending on the discharge time:
Discharging time
120 h (C120)
100 h (C100)
20 h (C20)
5 h (C5)
1 h (C1)
Procedure:
1. Determine the battery capacity C10 specified by the battery manufacturer.
2. If the battery capacity C10 is not specified, determine the battery capacity C1, C5, C20, C100 or C120 and use
the table provided to estimate the battery capacity C10. This will provide a value that is probably sufficient for
commissioning.
3. After commissioning, contact the battery manufacturer as soon as possible, request the C10 battery capacity and
set the correct battery capacity in the installation assistant. In this case, proceed as if you had replaced the battery
(see Section 13.8, page 135).
116 SI44M-80H-13-BE-en-15
®
, the Modbus interface must be activated. After activating the
Estimation
C120
C10 = /
1.28
C100
C10 = /
1.25
C20
C10 = /
1.09
C5
C10 = /
0.88
C1
C10 = /
0.61
SMA Solar Technology AG
Operating manual