11 Troubleshooting
SMA Solar Technology AG
Operating manual STP3-6-3AV-40-BE-en-12 85
3. Install the short circuit device.
4. Connect the measuring device for insulation resistance.
5. Short-circuit the first string.
6. Set the test voltage. The test voltage should be as close as possible to the maximum system
voltage of the PV modules but must not exceed it (see datasheet of the PV modules).
7. Measure the insulation resistance.
8. Eliminate the short circuit.
9. Measure the remaining strings in the same manner.
☑ If the insulation resistance of a string deviates considerably from the theoretically
calculated value, there is a ground fault present in that string.
10. Reconnect to the inverter only those strings from which the ground fault has been eliminated.
11. Reconnect all other strings to the inverter.
12. Recommission the inverter.
13. If the inverter still displays an insulation error, contact the Service (see Section14, page96).
The PV modules might not be suitable for the inverter in the present quantity.
