The solar inverter is the core component of the photovoltaic system, responsible for converting the direct current generated by the solar panels into usable alternating current. Its failure may directly affect the power generation efficiency of the entire system. The following are common types of faults, causes, and brief solutions for solar inverters:
1、 No output/non working fault
This is one of the most common faults, manifested as the inverter being connected normally but without AC power output, and the system unable to generate electricity.
Possible reasons:
DC input fault: The solar panel string is broken, the wiring is loose or burnt, resulting in no DC power supply to the inverter.
Communication output fault: Loose connection wire between inverter and grid/load, circuit breaker tripping, or AC side fuse melting.
Internal faults of the inverter: damage to the motherboard, burning of power devices (such as IGBT), or failure of the core control module.
Protection mechanism triggered: such as DC overvoltage/undervoltage, AC overvoltage/underfrequency, the inverter enters the protection state and stops working.
Response methods:
Check if the DC/AC wiring is secure, measure if the battery board voltage and grid voltage are normal, troubleshoot circuit breakers and fuses, and if the fault persists, contact professionals to inspect internal components.
2、 Grid connection failure
Inverter cannot connect to the grid normally, commonly seen in grid connected inverters, manifested as a "grid connection failure" alarm.
Possible reasons:
Abnormal power grid parameters: high/low power grid voltage, frequency exceeding the allowable range of the inverter (such as China's power grid standard of 220V ± 10%, 50Hz ± 0.5Hz).
Grid protection device triggering: such as anti islanding protection (the inverter needs to be disconnected immediately when the power grid is cut off to avoid "islanding effect"), grounding fault.
Communication failure: The communication module (such as RS485, Ethernet) between the inverter and the power grid monitoring system has malfunctioned, resulting in the inability to synchronize with the grid.
Response methods:
Check if the voltage and frequency of the power grid meet the standards, verify if the grounding is good, restart the inverter and attempt to reconnect to the grid. If frequent failures occur, investigate the stability of the power grid or the communication module of the inverter.
3、 Overheating fault
When the temperature of the inverter is too high during operation, it triggers overheating protection and shuts down, usually accompanied by a "high temperature" alarm.
Possible reasons:
Poor heat dissipation: The inverter fan is damaged, the heat sink is clogged with dust, or the installation environment has poor ventilation (such as high temperature, enclosed space).
Load overload: The inverter operates at full load or overload for a long time, causing severe heating of power devices.
High ambient temperature: During the high temperature period in summer, photovoltaic panels have high power generation efficiency, inverter loads are large, and the ambient temperature is high, which can easily trigger overheating.
Response methods:
Clean the dust on the heat sink, check if the fan is running properly, avoid the inverter running at full load during high temperature periods, and improve the ventilation of the installation environment if necessary (such as installing a heat sink fan or adjusting the installation position).
4、 Communication malfunction
The inverter and monitoring system (such as backend management platform, APP) cannot communicate, resulting in the inability to remotely monitor data such as power generation and status.
Possible reasons:
Communication line malfunction: The communication line is loose, aging, or interfered with (such as strong electromagnetic equipment nearby).
Communication module failure: The communication chip and interface inside the inverter are damaged, or the monitoring system software is malfunctioning.
Network issue: The signal of the network (such as 4G, WiFi) that remote monitoring relies on is weak or interrupted.
Response methods:
Check the communication cable connection, replace damaged lines, restart the inverter and monitoring system, test the network signal strength, and replace the communication module if there is a hardware failure.
5、 DC side fault
There is a problem with the DC side connected to the solar panel, which affects the DC input of the inverter and is commonly seen in string inverters.
Possible reasons:
String mismatch: Different battery board models and aging levels vary greatly, resulting in uneven string current/voltage and abnormal DC input of the inverter.
DC arc fault: Loose connection terminals or damaged insulation layer of the battery board, resulting in DC arc (with fire risk), triggering protection with inverter arc detection function.
DC overvoltage: When the sunlight is strong, the open circuit voltage of the solar panel is too high (such as multiple boards connected in series), exceeding the upper limit of the inverter's DC input.
Response methods:
Check if the string connections are consistent, replace aging or faulty battery boards, check if the wiring terminals are loose, and ensure that the DC voltage is within the rated range of the inverter.
6、 Display malfunction
The inverter display screen has no display, garbled text, or error messages that cannot be recognized, which affects troubleshooting.
Possible reasons:
Display hardware malfunction: screen damage, backlight module failure, or poor connection of connecting wires.
Software program error: Inverter firmware (system program) bug, causing abnormal display, usually accompanied by normal operation but display disorder.
Response methods:
Check the wiring of the display screen, restart the inverter and try to restore it. If the issue persists, it may be a firmware problem. Contact the manufacturer to upgrade the program or replace the display screen.
7、 Lightning/surge protection failure
The damage to the inverter lightning protection module is usually caused by lightning strikes or power grid surges.
Performance: The inverter has no output or the lightning protection indicator light is constantly on (fault state).
Response method: Check if the lightning protection module is burnt out, replace damaged lightning protection devices, and strengthen system lightning protection measures (such as installing external lightning arresters).
summarize
Solar inverter failures are often related to wiring, environment, grid parameters, or aging of internal components. In daily maintenance, it is necessary to regularly check the firmness of wiring, clean heat dissipation components, monitor the status of the power grid and battery panels to reduce the probability of failure. If complex faults occur (such as internal component damage), it is recommended to contact professional maintenance personnel or manufacturers for handling to avoid safety risks caused by self disassembly.
