G-PHASE: DC Bus Unbalance

The "G-PHASE" error indicates an imbalance in the DC voltage levels within the inverter's internal DC bus. The DC bus is a critical component that converts the variable DC power from the solar panels into a stable DC voltage before it's converted into AC power for the grid.

Why it's problematic

A significant voltage imbalance can disrupt the inverter's operation, leading to reduced efficiency, instability, and potential damage to components.
This imbalance can trigger protective mechanisms, causing the inverter to shut down and interrupt solar energy production.

Possible causes

Uneven irradiation on solar panel strings: Variations in sunlight exposure, shading, or dirt on different panels within a string can create different voltage levels, leading to a DC bus unbalance.
Faulty or mismatched solar panels: A damaged or underperforming panel within a string can cause a voltage drop, affecting the overall string voltage and contributing to an imbalance.
Wiring issues or loose connections: Poorly made connections or damaged wiring within the DC circuits can lead to voltage drops and imbalances.
Internal inverter fault: A malfunctioning component within the inverter, such as a capacitor or sensor, can affect voltage regulation and cause an imbalance.

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

Restart the inverter: A simple restart can sometimes resolve temporary glitches or communication errors.
Check for shading or dirt on solar panels: Inspect each solar panel in the array for any signs of shading, dirt, or debris. Clean the panels if necessary.
Check DC wiring and connections: Carefully examine all DC wiring connections between the solar panels and the inverter, looking for loose connections, corrosion, or damage. Tighten connections and repair or replace any damaged wiring.
Isolate and test individual strings: If the inverter has multiple MPPT inputs, disconnect each string one by one and observe if the error clears. This can help identify a problematic string.

Verifying the solution

Monitor the inverter's display for the disappearance of the "DC Bus Unbalance" error. If the voltage levels have balanced, the inverter should resume normal operation. This is typically indicated by status LED lights and power generation readings on the display.

If the problem is not resolved

If the error persists after following all the above steps, there might be an internal fault within the inverter.

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.