PROBLEM
After installation and commissioning of SUN2000-100KTL-M1, the system has been working for more than a year untill one day when the customer call that the entire system went down.
OBSERVATIONS
On the inverter LED display, the LED 2 is OFF, LED 4 was steady Red.
When FusionSolar App was connected to the inverter via external WLAN Adaptor, after logging in, and clicking on "Alarm management". The Alarm ID was 2061.
TROUBLESHOOTING
Check the impedance of the PV string to PE. If a short circuit occurs or the insulation is insufficient, rectify it.
Check that the PE cable of the solar inverter is correctly connected.
If you are sure that the impedance is less than the default value in a cloudy or rainy environment, reset Insulation resistance protection
POSSIBLE CAUSES
The PV string is short circuited to PE.
The PV string has been in a moist environment for a long time and the circuit is not well insulated to ground.
CONCLUSION AND SUGGESTION
After going through the throubleshooting steps, it was observed that the positive DC cable of string 1 from the PV panels to the inverter that went through the Underground conduit pipe has damaged. The insulation of the DC cable was damaged probabily during the process of pulling the DC cable and there was moisture in the DC cable. The inverter was tested with each string connected to be sure that the problem is only from string 1.
SOLUTION
Both the positive and the negative DC cable of the string1 was replaced and the system came back up.
