When deciding whether the “Q at Night” option is suitable for your project, you should take various aspects into consideration. These subjects will be explained in detail in the following sections.
3.1 Limiting the Reactive Power in the “Q at Night” Operation
The maximum possible reactive power is limited in the “Q at Night” operation for the protection of the MV transformer. Thirty percent of the nominal power of the inverter can be fed in and the respective limits are set permanently in the parameters.
3.2 Retrofitting of Existing Plants
Sunny Central CP XT inverters from fabrication version B4 can be retrofitted with the hardware components for the “Q at Night” option. The new parameters will be made available via a firmware update. An extra AC cable must be laid between inverter and customer-side MV transformer in addition to the adjustments to the inverter. Contact the SMA Service Line with any questions regarding this subject.
3.3 Economic Viability of the Option “Q at Night”
The investment costs of the option “Q at Night” are significantly lower in comparison to the costs for compensation plants. In particular, the savings are considerable compared to dynamic compensation plants. Additional operating costs must be considered for the overnight internal power supply of the inverter.