SMA SUNNY BOY STORAGE 3.8-US Instructions D'installation page 24

4 Product Overview
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 enabled 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
4.4 LED Signals
LED signal
The green LED is flashing
(two seconds on and
two seconds off)
24 SBSxx-US-10-IA-xx-14
100
50
−4 −3 −2 −1
f [Hz]
Explanation
Base frequency of the stand-alone grid
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.
Explanation
Waiting for feed-in conditions
The conditions for feed-in operation are not yet met. As soon as the
conditions are met, the inverter will start feed-in operation.
f Start Delta (1 Hz)
f Limit Delta (2 Hz)
f Delta+ (4.5 Hz)
0 +1 +2 +3
SMA Solar Technology AG
+4
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