SMA SI 3.0-11 Installation - Manual (Page 82)

8 Commissioning SMA Solar Technology AG
82 SI30M-44M-60H-80H-IA-en-30 Installation Manual
8.3.6 Setting Utilization of Excess Energy in Off-Grid Systems
Figure 25: Switching-on time and switching-off time for utilization of excess energy during constant voltage phase
The Sunny Island controls the utilization of excess energy during the constant voltage phase depending on the cell
voltage of the battery. During the constant voltage phase, the battery is charged with a constant charging voltage.
When the setpoint of the cell voltage in the constant voltage phase is reached, the multifunction relay is activated. The
multifunction relay remains in this position for the minimum time 241.07 ExtPwrDerMinTm. If the cell voltage differs by
more than 241.08 ExtPwrDerDltVtg from the setpoint of the cell voltage, the multifunction relay is deactivated. The
setpoint of the cell voltage depends on the charging process during the constant voltage phase.
To control the utilization of excess energy, set the multifunction relay as follows:
Procedure:
1. Switch to installer mode on the Sunny Remote Control (see Section 8.4).
2. Select the parameter 241.07 ExtPwrDerMinTm and set it to the minimum time that the multifunction relay remains
activated.
3. Select the parameter 241.08 ExtPwrDerDltVtg and set it to the voltage difference relative to the setpoint of the
cell voltage during the constant voltage phase.
4. Ensure that the multifunction relay used for control is set to ExtPwrDer (see Section 8.1.5 "Setting the Functions of
the Multifunction Relays", page 66).
Charging process Parameter Default value
Fast charge 222.07 ChrgVtgBoost 2.40 V
Full charge 222.08 ChrgVtgFul 2.45 V
Equalization charge 222.09 ChrgVtgEqu 2.45 V
Recording of the measured values of the cell voltage reacts to changes with time-lag
The Sunny Island calculates the cell voltage from the measured battery voltage. The Sunny Island calculates
an average from the measured values of the battery voltage. As a result of the calculation of an average, the
cell voltage that is recorded reacts to changes with a time-lag.