OV-BUS: DC bus overvoltage

This guide explains how to troubleshoot a "OV-BUS" error on an Autarco inverter. This error indicates that the voltage in the inverter's DC bus, which connects to the solar panels, has exceeded the safe operating limit.

Why it's problematic

High DC voltage can damage the inverter's internal components, leading to malfunctions or permanent failure. To protect itself, the inverter shuts down when this error occurs.

Possible causes

Excessive solar panel voltage: The solar panels might be generating more voltage than the inverter can handle, especially in conditions of high irradiance or low temperature.
Incorrect wiring: Faulty or incorrect wiring of the PV array can lead to voltage imbalances or spikes, exceeding the inverter's limit.
Faulty inverter components: A malfunctioning component within the inverter, such as a capacitor or sensor, might contribute to the overvoltage condition.

Before you begin

Safety First: Working with electrical equipment always involves risks. Ensure you are qualified and follow appropriate safety precautions. Disconnect the inverter from both AC and DC sources before performing any physical inspection or adjustments.

Gather Information: Before starting troubleshooting, have the inverter manual on hand. You should also gather information about the inverter model and serial number, the installation date, and the PV array configuration (number of panels, capacity, and number of strings).

Troubleshooting steps

Verify PV array configuration: Ensure that the PV array's voltage rating is compatible with the inverter's maximum input voltage. Refer to the inverter's datasheet and the solar panel specifications.
Inspect the DC wiring: Carefully check all wiring connections between the solar panels and the inverter, ensuring they are tight, secure, and free from damage or corrosion.
Measure the PV array voltage (Certified Installers Only): Using a multimeter, measure the open-circuit voltage of each string in the PV array and compare it to the inverter's maximum input voltage limit.
Check for shading: Uneven shading on the solar panels can cause voltage imbalances, potentially leading to overvoltage. Ensure that all panels are receiving uniform sunlight.

Verifying the solution

After addressing the potential causes, power on the inverter and monitor the DC bus voltage through the inverter's display or monitoring system. If the voltage remains within acceptable limits and the error does not reappear, the problem is likely resolved.

If the problem is not resolved

If the error persists, there might be a more complex problem involving a faulty inverter component or a persistent overvoltage condition that requires further investigation.

As a system owner: In this case, contact the inverter installer or distributor for further assistance. You can find the details of your installer in the MyAutarco app.
As a certified installer: Contact Autarco Support, you can submit a support case via Helios.