As an important component of the entire power plant, inverters can detect almost all power plant parameters for both DC components and grid connected equipment. If there is an abnormality, the health status of the supporting equipment in the power station can be checked through the feedback information from the inverter. Below are some common fault information and handling methods for photovoltaic inverters.

No mains connection
Cause of malfunction:

Indicates that there is no connection to the mains or the AC circuit breaker is disconnected, causing the inverter to not detect the voltage of the mains.
Solution:

1. Determine whether the power grid is experiencing a power outage. If the power grid is experiencing a power outage, wait for it to resume power supply.

2. If the power supply to the grid is normal, use a multimeter to measure the AC output voltage to see if it is normal. First, measure the inverter output port and check if there is a problem on the inverter output side. If there is no problem, it is a broken circuit on the external AC side. It is necessary to check the safety switches such as the air switch, knife switch, overvoltage/undervoltage protector in sequence for any damage or open circuit.

AC voltage out of range

Cause of malfunction:

When photovoltaic power generation is connected to the user side grid, the voltage at the connection point will increase. The greater the internal resistance of the power grid, the greater the appreciation. The closer it is to the transformer, the smaller the line resistance, and the smaller the fluctuation of the power grid. The further it is to the end of the power grid, the longer the line, and the greater the voltage fluctuation. Therefore, when the inverter is connected to the power grid far from the transformer, the working environment of the inverter's power grid will become very poor. When the upper limit of the inverter's working voltage is exceeded, the inverter will report a fault and stop working. According to the technical specifications for photovoltaic grid connected inverters, the requirements for overvoltage/undervoltage protection on the AC output side: when the AC output voltage of the inverter exceeds the allowable voltage range of the grid, the inverter is allowed to disconnect from the power supply to the grid, and a warning signal should be issued when the disconnection occurs. When the grid voltage returns to the allowable voltage range, the inverter should be able to start and operate normally.

Solution:

1. Try to place the access point of the photovoltaic power station as close as possible to the output end of the transformer to reduce line losses.

2. Try to shorten the length of the AC output line of the inverter or use thicker copper core cables to reduce the voltage difference between the inverter and the power grid.

3. Nowadays, the vast majority of grid connected inverters have AC voltage regulation function. You can contact the manufacturer to adjust the AC voltage range to adapt to grid voltage fluctuations.

4. If possible, the output voltage of the transformer can be appropriately lowered.

Low insulation impedance

Cause of malfunction:

The inverter has the function of detecting the insulation impedance on the DC side. When the impedance of the DC positive and negative poles to the ground is less than 50k Ω, the inverter will report a "PV insulation impedance low fault". In order to prevent human contact with the live parts of the panel and the ground at the same time, which may cause electric shock hazards. The influencing factors include: DC component leakage; cable insulation damage, wet exposed live parts; poor grounding of component brackets; high humidity in weather and power station environment, etc.
Solution:

Disconnect the AC/DC air switch, use a dedicated MC4 disassembly wrench to remove the positive and negative poles of the DC measurement string to ensure reliable grounding of the component bracket. Use a multimeter megohm range, connect the red meter pen to the positive pole of the group, and connect the black meter pen to the ground. Read the impedance readings of each positive pole to ground measured, then connect the red meter pen to the negative pole of the group, and then read the impedance readings of each negative pole to ground. If it is greater than 50k Ω, it is judged that the insulation of the group is reliable. If it is less than or equal to 50k Ω, it is judged that there is a problem with the insulation of the group. The cable condition of the group can be checked separately for any damage or lack of contact. The insulation impedance is low, usually due to a short circuit between the positive and negative poles to ground.
Excessive leakage current

Cause of malfunction:

The inverter leakage current detection module detected excessive leakage current. To protect personal safety, it stopped working and reported the fault information.

Solution:

1. Disconnect the PV input, restart the machine, and observe if the machine can return to normal.

2. Check whether the AC ground wire is connected to the live wire, measure whether the voltage between the ground wire and the live wire is normal, or use a leakage current detector to detect it.

If there is no connection between the measuring ground wire and the live wire, it is likely that the machine is leaking electricity and needs to contact the manufacturer for handling.

DC voltage too high

Cause of malfunction:

Too many series components in a single PV string result in voltage exceeding the PV voltage limit of the inverter

Solution:

Check the parameters of the inverter, determine the input range of DC voltage, and then measure whether the open circuit voltage of the string is within the allowable range of the inverter. If it exceeds the allowable range, reduce the number of components in the string in series.

Similarly, if the PV voltage is reported to be too low, check if the number of components connected in series is too small, or if the positive and negative poles of the string are reversed, the terminals are loose and the contact is poor, or the string is open.

No display on the inverter screen

Cause of malfunction:

1. There is no DC input or auxiliary power failure, the inverter LCD is powered by DC, and the component voltage cannot reach the inverter startup voltage.

2. The PV input terminals are connected in reverse. The PV terminals have positive and negative poles that correspond to each other and cannot be connected in reverse with other groups.

3. The DC switch is not closed.

4. One component is open circuit, causing other strings to not work either

Solution:

1. Use a multimeter to measure the DC input voltage of the inverter. When the voltage is normal, the total voltage is the sum of the voltages of each component.

2. If there is no voltage, check whether the DC switch, wiring terminals, cable joints, components, etc. are normal in sequence.

Monitoring issues

Cause of malfunction:

The collector and inverter are not communicating; Collector not powered on: installation position signal issue; Internal reasons of the collector

Solution:

1. Check if the communication interface between the collector and inverter is normal, and observe the status of the communication indicator light;

2. Check the local signal strength, and areas with weak signals should be equipped with enhanced antennas

3. Scan the correct collector serial number

If there is no problem with the external conditions and the collector does not respond to any connections, it can be considered that there is an internal fault in the collector.