SMA SUNNY BOY STORAGE 3.8-US Instructions D'installation page 21

SMA Solar Technology AG
You can configure times and setpoints for the power drawn at the grid-connection point. When the
loads require additional energy, the battery is discharged and the maximum value is kept constant
at the grid-connection point This is based on the prerequisite that the battery is sufficiently charged.
At times when the "Peak Load Shaving" function is not activated, the battery is charged or
discharged correspondent to the increased self-consumption for the entire system. The "Peak Load
Shaving" function is deactivated by default and must be activated by creating power profiles.
Frequency Shift Power Control
If PV inverters are connected on the AC side during battery-backup operation, the battery inverter
must be able to limit their output power. This limitation becomes necessary when, for example, the
battery inverter's battery is fully charged and the power available from the PV system exceeds the
power requirement of the connected loads.
To prevent excess energy from overcharging the battery, the battery inverter automatically detects
the problem and changes the frequency at the AC output. This frequency adjustment is analyzed by
the PV inverter. As soon as the power frequency of the battery-backup grid increases beyond the
value specified in f Start Delta, the PV inverter limits its output power accordingly.
The frequency shift power control is activated by default. No additional settings must be carried
out. It must be ensured that the connected PV inverters limit their power at the AC output via the
battery inverter due to changes in frequency. The frequency-dependent active power limitation P(f)
must be set in the PV inverter.
f Delta− (4.5 Hz)
Figure 3 : Impact of the frequency shift power control on the power output of a PV inverter
Designation
f
f Delta- to f Delta+
f Start Delta
f Limit Delta
Installation Manual
100
50
−4 −3 −2 −1
f [Hz]
Explanation
Base frequency of the stand-alone grid (50 Hz)
Maximum range in relation to the base frequency in which the PV inverter
is active.
Frequency increase in relation to the base frequency, at which point the
power regulation via frequency begins.
Frequency increase in relation to the base frequency, at which point the
power regulation via frequency ends.
The power of the PV inverter at this point is 0 W.
f Start Delta (1 Hz)
f Limit Delta (2 Hz)
f Delta+ (4.5 Hz)
0 +1 +2 +3
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4 Product Overview
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