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As the "heart" of photovoltaic power generation, the health of the inverter is closely related to the smooth operation of the photovoltaic power generation system. Understand common inverter alarms and accurately determine the cause of inverter alarms.

1. Inverter alarms not caused by internal components

If "Warning 103 or Warning 105" is displayed on the screen or APP, it means that the reading and writing of EEPROM failed, and it can usually be repaired by restarting the inverter. If "Warning 100 or Warning 400" is displayed on the screen or in the APP, it means that the fan is in an alarm. First check whether the fan is stuck by foreign objects, and then manually stir the fan when the power is off, and restart the inverter. It is recommended that the inverter should clean the fans regularly every six months.

2. Inverter alarms caused by common external environments

1. The LCD displays "No AC Connection".

This type of alarm means "no mains connection", and generally occurs in single-phase inverters, indicating that the mains is not connected or the AC circuit breaker is disconnected. If such an alarm occurs, check whether the AC side line is well connected and whether the AC switch is closed.

2. The LCD displays "Overtemperature".
This type of alarm means "inverter overheating". Generally, the place where the inverter is installed is insufficiently ventilated, the inverter is exposed to the sun, and the inverter fan is abnormal. To solve this problem, it is first necessary to ensure that the place where the inverter is installed is ventilated to avoid exposure to the sun. For fan abnormality, check whether the NTC line and the NTC temperature sampling circuit are well connected.
3. The LCD displays "PV Isolation Low".
This type of alarm indicates "insulation resistance is too low", which may be caused by panel insulation, cable insulation, component support grounding reliability, installation site temperature and humidity, etc.
To check this abnormality, first disconnect the AC and DC circuit breakers, remove the positive and negative poles of the DC measuring string with a special MC4 disassembly wrench, then use a multimeter with a megohm gear, connect the red test lead to the positive pole of the string, and the black test lead to ground, and read Measure the impedance reading of each positive electrode to ground, and then connect the red test lead to the negative electrode of the string, and read the impedance readings of each negative electrode to ground one by one. If it is greater than 50kΩ, the inverter judges that the insulation of the string is reliable, and it is less than or equal to 50kΩ. If the inverter judges that there is a problem with the insulation of the string, the inverter will automatically protect and stop working and report "insulation resistance is too low".
4. The inverter screen is not displayed.
The inverter does not display because the LCD has no DC input or the auxiliary power supply is abnormal. In this case, use a multimeter to measure the DC input voltage of the inverter. The total voltage is the sum of the voltages of each component, so the voltage problem is ruled out. After eliminating the voltage problem, check whether the DC switch, terminal blocks, cable connectors, components, etc. are normal.
The above is the cause analysis and general treatment methods for common inverter alarms. When the above methods cannot repair the inverter alarm, please contact the relevant staff in time, and do not force the repair by yourself.