Ground fault
SMA · Sunny Boy Solar Inverter
What does 3501 mean?
A ground fault is present in the PV system, indicating that the electrical insulation from the PV system to ground is defective or insufficient. This poses a danger of electric shock and can reduce system performance.
Common Causes
- Defective electrical insulation from the PV system to ground.
- Insufficient electrical insulation from the PV system to ground.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Disconnect the inverter from all voltage sources (refer to Section 10, page 60).
- 2
Measure the voltage between the positive terminal and ground (PE), negative terminal and ground (PE), and positive and negative terminals.
- 3
If all measured voltages are stable and the sum of the two voltages to ground equals the voltage between positive and negative terminals, determine and eliminate the ground fault location via voltage ratio.
- 4
If voltage measurement is inconclusive, calculate the expected insulation resistance per string.
- 5
Install a short circuit device, connect an insulation resistance measuring device, set the test voltage (close to but not exceeding PV module max system voltage), and measure resistance for each string.
- 6
If a string's insulation resistance deviates considerably from the calculated value, eliminate the ground fault in that specific string and then reconnect only the rectified strings to the inverter.