Check wires of PV and ground:
- Turn OFF AC switch to disconnect inverter from Grid.
- Open fuse drawers to de-couple PV strings from each other. Test strings with string test set
- Add one PV string at a time and start up inverter to see if alarm occurs.
- If there is no alarm, turn OFF AC switches to disconnect from Grid and add in the next string. Startup inverter again.
- Continue until you can find the string that triggers the alarm. Trace wirings of faulted string to find any leakage to Earth Ground.