Options for the & # 39; G_PHASE & # 39; fault in solar inverters – Mercom Germany

In the case of photovoltaic (PV) solar systems, problems on the grid side can lead to errors. Inverters are a critical operational function of a PV system and the grid, are very sensitive to grid problems and react quickly. Grid imbalance errors, although rare, can easily affect inverters, PV systems, and sometimes even loads.

Wrong description

When starting, the Soils inverters recognize the status of the grid. If the grid phase is asymmetrical, the inverter disconnects from the grid and displays the "G_PHASE" error.

Reasons of "G-PHASE "error

Voltage imbalance on the network side

"Grid asymmetrical" is an important problem that causes this alarm for the inverter as it monitors the grid voltage in real time. If the three-phase grid waveform is abnormal, the inverter will give feedback immediately and disconnect from the grid.

Figure 1. Waveform diagram for an unbalanced grid

Large devices used affect the network and lead to network instability.

In the case of PV systems installed in industrial areas, inverters are more susceptible to alarms from the grid, such as B. Grid overvoltage, grid imbalance and grid imbalance. This is all because the operation of large current devices affects the operation of the inverter via the grid.

Figure 2. Network problems caused by various load surges


An oscilloscope can be used to check that the three-phase voltage and the network waveform are normal. If not, the waveform can be recorded and reported to the Solis technical team for assistance.

Possible causes related to the inverter

The AC cable is connected incorrectly

Errors during the installation process can be caused by incorrectly connected cables, which leads to phase imbalances in the power supply.

Figure 3. Connection failure in the cable sequence


Reconnect the AC cable and make sure the wiring order is correct.

The AC cable used in the PV system is unsuitable

If an unsuitable cable is selected during the design process, e.g. For example, an inferior AC cable made of inferior material or small diameter can cause problems. The system will come into contact with the metal of the cable due to the heating of the current during long term operation of the system. The film is deformed and blackened and the impedance is significantly different, which makes the three-phase voltage appear unbalanced and the inverter triggers the alarm.


The correct cable selection and specifications can be found in the Solis inverter manual, which contains detailed cable recommendations.

The inverter's AC terminal has poor contact

If there is a problem with the inverter's AC terminal, such as B. a loose cable, poor cable contact, etc., this alarm is also displayed. In such cases, replace the inverter's AC terminal.

The G_PHASE error is a rare problem, but it still causes the system to shut down and affect power generation. If this fault occurs in a PV system, it must therefore be rectified immediately in order to minimize system downtime.

This article is sponsored by solar inverter manufacturer Ginlong Technologies.

Image source: Solis

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