1. Thermal photocurrent effect appears on the solar panel: the solar panel in the solar inverter may be irradiated by nearby light sources, especially in the dark, which may produce certain thermal photocurrent effect. This effect will make the solar panel produce a small amount of current output, which will be displayed on the branch circuit of the inverter.

2. Leakage problem: In the night environment, there may be leakage problem in the inverter branch. This may be caused by line failure, poor contact or ground wire problems. Leakage will cause current to flow in the inverter branch.

3. Problems of the inverter itself: The inverter may be faulty or damaged, resulting in abnormal branch current display. This may require professional technicians to diagnose and repair the inverter.

In this case, I suggest you take the following steps:

1. Check the light source: Make sure that no light source directly illuminates the solar panel of the inverter.

2. Check the circuit: Check whether the power supply circuit and data circuit of the inverter are damaged or have poor contact.

3. Check the status of the inverter: Check the status indicator light or display screen of the inverter to confirm whether there are other fault prompts.

If the problem cannot be solved, it is recommended that you contact professional solar inverter maintenance personnel for further diagnosis and maintenance.