Low system insulation resistance means there is insufficient electrical insulation to ground, possibly due to dampness or poor cable insulation. The manual's first action is: “1. Check whether the ISO resistance protection value is excessively high via the APP or the LCD, and ensure that it complies with the local regulations. 2. Check the resistance to ground of the string and DC cable. Take correction measures in case of short circuit or damaged insulation layer. 3. If the cable is normal and the fault occurs on rainy days, check it again when the weather turns fine. 4. If the fault is not caused by the foregoing reasons and still exists, contact Sungrow Service.”
- Model
- Sungrow SG125HV/SG125HV-20
- Display shows
- Low system insulation resistance (039)
- Type
- Fault code
- Source
- Manual p. 81
What 039 means
Low system insulation resistance p. 81
Common causes
- Generally caused by poor insulation to ground/cable or by rainy and damp environment. p. 81
What to do
- 1. Check whether the ISO resistance protection value is excessively high via the APP or the LCD, and ensure that it complies with the local regulations. 2. Check the resistance to ground of the string and DC cable. Take correction measures in case of short circuit or damaged insulation layer. 3. If the cable is normal and the fault occurs on rainy days, check it again when the weather turns fine. 4. If the fault is not caused by the foregoing reasons and still exists, contact Sungrow Service. p. 81
Before you service the product, read the safety instructions in the manual p. 5.
If 039 is still not resolved
This page summarises what the manufacturer’s manual says about 039; each statement links to the page it comes from, and quoted lines are copied word for word. It is not a substitute for the manual or for a qualified installer. ManualLib is not affiliated with Sungrow. Found a mistake? Report an error.