Hi, I have the following AC coupled configuration
The 2 PV arrays are IQ7 Enphase micro's at each panel
The 2 Multi's are 48/5000/70-50 and are configured with ESS assistant and frequency shift capability according https://www4.enphase.com/en-au/support/ac-coupling-enphase-microinverters-grid-applications.
The battery system is 500Ahr
The problem I am having is that the frequency of the AC OUT of both Multi's is continuously jumping from 50 to 53 Hz (approx. every 5 - 10 sec.). The IQ7's don't like this and report frequency/grid instability errors and therefor don't produce any power. They work fine when directly connected to the grid. Battery still 60% SoC but getting lower as we speak, because there is no charge.
Please help me resolve this issue ? Why is the frequency jumping ?