Anenji ANJ-SP-2200-12V inverter erroneously switching to PV

I own an Anenji ANJ-SP-2200-12V inverter, which is currently not connected to any solar panels. It is, however, hooked up to a single LiFePO4 12V 150Ah battery and the utility grid. I'm encountering an issue where, every few seconds, the inverter detects voltage at the PV input and attempts to switch to PV. In second or so voltage disappears, causing the inverter to emit a loud beep and halt charging the battery from the utility grid. This cycle of detecting voltage and then losing it repeats continuously until the inverter is disconnected from power.

Upon measuring the voltage at the PV input, I confirmed it aligns with the inverter's readings, showing approximately 120V. I'm at a loss as to the source of this voltage and how to resolve the issue. Could this problem stem from incorrect installation, or is it indicative of a defect in the inverter itself?

Hi! you can check this inverter whether has solar priority setting, usually solar inverter there are some operation mode, like solar power priority, AC grid priority, or battery priority.

Is your inverter grounded?

orsonz said:

Hi! you can check this inverter whether has solar priority setting, usually solar inverter there are some operation mode, like solar power priority, AC grid priority, or battery priority.

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Hi! The inverter supports only two modes: SBU and SUB. In both modes, solar power is given the highest priority.

meetyg said:

Is your inverter grounded?

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No, the inverter is not grounded due to the absence of grounding infrastructure in the building.

Azgort said:

No, the inverter is not grounded due to the absence of grounding infrastructure in the building

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So you might have some inductive currents showing up on the PV line.
Your utility input isn't grounded either? If not,
I would definitely ground the inverter to a dedicated ground/earth rod. See if it helps.

I've returned the inverter to the seller, who confirmed it was defective. Currently waiting for the repair.