F47 AC_OverFreq_Fault When in MI/String Inverter Set-Up

When operating a smaller Sunsynk inverter as a string inverter connected to the GEN connections on a larger Sunsynk inverter, the smaller unit may experience frequent F47 faults. 

The larger Sunsynk unit outputs 230V 50Hz, to the GEN terminals which becomes the ‘grid’ supply for the smaller unit 

The fault occurs because when MI Zero Export is enabled or you have an export limitation set, the larger main Sunsynk unit controls the output of the connected inverter in string set-up by frequency shifting. 

Therefore, when the smaller inverter detects a frequency shift outside the permitted range, an F47 AC_OverFreq_Fault is triggered. This alarm can therefore be expected in this set-up, and the unit is operating as designed.