Low Insulation Resistance

What does Low insulation resistance mean?

This alarm signifies that the insulation resistance of the PV strings or associated DC power cables connected to the SUN2000 inverter is below an acceptable threshold, indicating a potential ground fault or short circuit. If the irradiance or PV string voltage is too high, the fault location feature may fail, displaying 'Conditions not met'. This condition poses a risk of electrical shock and equipment damage.

• Damage to the insulation of PV modules, DC power cables, or connectors due to aging, environmental stress, or mechanical wear.
• Moisture ingress into PV module junction boxes or DC connectors compromising insulation.
• Accumulation of dirt or debris on PV module surfaces creating conductive paths.

Click steps to track your progress.

1. 1

   Ensure all AC connections to the SUN2000-(250KTL, 280KTL, 300KTL, 330KTL) are normal.

2. 2

   Log in to the FusionSolar app, choose Maintenance > Inverter ON/OFF, and send a shutdown command to the inverter.

3. 3

   Set the DC SWITCH of the SUN2000 inverter to OFF.

4. 4

   Connect PV strings to the SUN2000 one by one to isolate the faulty string.

5. 5

   After connecting a single string, set the DC SWITCH to ON. If the inverter status is 'Shutdown: Command', send a startup command via Maintenance > Inverter ON/OFF in the app.

6. 6

   On the FusionSolar app, choose Alarm, enter the Active alarm screen, and check for the 'Low insulation resistance' alarm 1 minute after DC power-on. If reported, check the percentage of possible short-circuit positions on the Alarm details screen to locate the faulty PV module, then set the DC SWITCH to OFF and inspect the connectors or DC power cables between the possibly faulty PV modules for damage.