Retrofit of PV plants in Germany for 50.2 Hz issue

Change of frequency settings according SysStabV

In normal circumstances, the European power grid functions at a frequency of 50 Hertz (Hz). When more energy is fed in to the power grid than is removed from it, the grid frequency increases. Excessively high frequencies render the grid unstable and so until 2011, inverters for photovoltaic systems were equipped with an automatic switch-off function triggered at the fixed frequency of 50.2 Hz. Since there are now PV systems in Germany with more than 30 GW of installed power, there is a risk that significant power outputs will be switched off when the frequency limit is exceeded. This would have a considerable effect on grid stability in lager areas. Preventative measures are necessary to avoid this risk. In accordance with the System Stability Regulation (SysStabV) passed by the Federal German Government on May 4, 2012, power inverters must have the capability to reduce their output during overfrequency or to turn themselves off smoothly. If the technical requirements to do so are not met, the law requires that many devices be switched off at different frequencies. To ensure that switch-off proceeds in this staggered manner, the grid switch-off frequency must be adjusted in inverters installed in existing systems.

The following types of existing systems are affected by this retrofit:

  • Systems with outputs greater than 10 kWp connected to the low-voltage grid that were commissioned after August 31, 2005 but before January 1, 2012 (systems on roofs, e.g. those on single family homes, are generally connected to the low-voltage network). 
  • Systems with output of over 30 kWp connected to the medium-voltage network that were commissioned after April 30, 2001 but before January 1, 2009.  
  • Systems with outputs of over 100 kWp connected to the medium-voltage network that were commissioned after April 30, 2001 but before January 1, 2012.  

We have developed a process to update Delta inverters installed during the periods described above that allows them to comply with the requirements of SysStabV.  

Retrofitting approach

The following table lists all Delta inverters that require retrofitting.

String inverters with a transformer String inverters
without a transformer
Central inverters
SOLIVIA 2.5 EU G3 TR SOLIVIA 15 EU G3 TL SOLIVIA CS xx G3
SOLIVIA 3.0 EU G3 TR SOLIVIA 20 EU G3 TL SOLIVIA CM xx G3
SOLIVIA 3.3 EU G3 TR   100 kW 3PH DES
SOLIVIA 5.0 EU G3 TR    

To retrofit string inverters, the installer updates the firmware.

Please follow the instructions in the manual "Frequenzumstellung bei Delta Solar Wechselrichtern entsprechend SysStabV".

For central inverters, the new cutoff frequency must be set by Delta Support or a Delta-certified installer.

Downloads
Type Name Size Date
Handbuch_Frequenzumstellung_bei_Delta_Solar_Wechselrichtern_SysStabV.pdf 2.4 MB 18/06/2014