32 Program features
Night Q production
During normal inverter operation, the inverter enters sleep mode when the sun goes down
since there is no active power available from the solar panels. This ends both active and
reactive power production. However, reactive power production during the night may be of
use to the solar plant by eliminating the need for extra reactive power compensation at
sites where it would otherwise be required.
The night reactive power (Night Q) production function is deactivated by default. It can be
activated or forced on using parameter 213.51 Night Q production. The operation of night
Q production is as follows:
• When the inverter enters Sleep mode, the reactive power reference is checked. If the
absolute value of the reactive power reference is larger than the value in parameter
213.52 Night Q low power, the inverter disconnects from the DC side, but not from the
AC side, and continues to generate reactive power. If the mode is forced on, it stays
connected to the AC grid even if the absolute value of the reactive power reference is
smaller than the value in parameter 213.52 Night Q low power. The shut down
procedure without the effect of reactive power is shown in Night Q production curve.
The figure shows the inverter shut down operation and night Q transition operation
when the active power is below the minimum power limit for the delay time defined by
parameter 213.17 Disconnection delay for sleep-mode.
Figure 12. Night Q production curve
Normal transition to night
DC voltage and solar array voltage
Active power
Minimum DC voltage
Solar array voltage
DC voltage in Night Q
DC voltage in normal standby
Solar panels connected to the inverter
Inverter connected to the grid Yes
Yes
No
Yes, if Night Q is active
Otherwise no
213.17 Disconnection delay for sleep-mode
213.16 Min power for sleep
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