Event 3701

Qualified person

Event message:

  • Residual current too high

  • Check generator

Explanation:

The inverter has detected a momentary insulation error of the PV modules. As soon as the values are back in the permissible range, the inverter reconnects. The error is exacerbated by climatic conditions such as high humidity in the morning and evening, as well as when it is raining.

Corrective measures:

  • Ensure that the AC voltage between L and N, L and PE, and N and PE at the AC connection of the inverter and in the subdistributor is in the permissible range. For three-phase inverters, perform the measurements for all connection line conductors.

  • Using a suitable measuring device, ensure that the voltage between N and PE is less than 10 V.

  • Ensure that the module frame is correctly grounded.

  • Check the PV system for ground faults.

  • Check the frequency and duration of the event message in the inverter's user interface or in the Sunny Portal. The measurements listed below should be performed under the same ambient conditions and at the same time of day as when the error occurred—ideally while an event message is active.

  • If module electronic components, such as SunSpec-compatible module disconnectors, are present, an additional device is required to maintain the SunSpec PLC signal.

  • Verify through measurement of the open-circuit voltage of the PV strings that the measured values correspond to the system design and prevailing irradiation conditions.

  • Measure the voltage of each PV string between DC+ and PE, and between DC− and PE, using a suitable measuring device. If a stable voltage is measured that approximately equals the string voltage, this indicates a ground fault. Correct the ground fault on the relevant PV string and only then reconnect.

  • Measure the insulation resistance of each PV string using an insulation resistance meter. Ensure that the PV string is short-circuited during these measurements and that the maximum permissible system voltage of the PV modules is not exceeded. If the insulation resistance is too low, it indicates a ground fault. Correct the ground fault on the relevant PV string and only then reconnect.

  • Visually inspect the entire DC installation (PV modules, cables, plug connections, and any existing components such as module optimizers or disconnectors) to ensure there are no signs of damage, such as porosity, cracks, crushing, deformation, or discoloration. Replace or repair any defective components.

    Tip: Use an IR camera for support.

    Event 3601
    Event 3901