DC Bus high – GoodWe

Description

This fault indicates that the inverter is detecting an abnormally high DC voltage on the internal bus.
This condition may be related to an input voltage exceeding the limit specified in the datasheet or to internal damage to the inverter’s bus components.

Troubleshooting Steps

1. Check firmware version

a. Access the inverter information and verify if both ARM and DSP firmware versions are up to date.
b. If they are not running the latest version, update the firmware before proceeding with any other troubleshooting.

Note: Firmware update must always be the first step in any troubleshooting procedure.

2. Check DC input voltage

a. When the fault occurs, measure the total DC voltage of the PV array (string).
b. Compare the measured voltage with the maximum input voltage specified in the model’s datasheet.

Note: If the voltage exceeds the maximum allowed value, the fault is caused by overvoltage.
The PV system must be reconfigured (for example, by reducing the number of modules in series).

3. Check balance between BUS and NBUS voltages

a. Access the inverter’s internal parameters (via local monitoring or service platform).
b. Compare the BUS and NBUS voltages:

Under normal conditions, BUS should be approximately twice the value of NBUS.
Example: if BUS = 100 V, NBUS should be around 50 V.

Caution: If there is a significant imbalance (for example, BUS = 100 V and NBUS = 20 V or 30 V), this indicates a hardware failure in the bus circuit.
In this case, the inverter should be sent for RMA.

4. Assess fault recurrence

a. Check if the fault occurs repeatedly, even after restarting the inverter or under different irradiance conditions.
b. If the fault persists, the inverter is likely damaged.

Procedure: Proceed with RMA analysis according to internal process.

Conclusion

In most cases, the “High DC Bus” fault indicates internal inverter damage.
If the DC input voltage is within the datasheet limits but there is a BUS/NBUS imbalance or the fault occurs frequently, the case should be escalated for RMA evaluation.

Related to