What Should I Do If My PV Inverter Frequently Malfunctions?
In a PV system, the inverter is the "energy conversion hub," converting the DC power generated by the solar panels into AC power for the load. A problem with the inverter not only affects power generation efficiency but, in severe cases, can even cause the system to shut down. To help customers troubleshoot more efficiently, Xindun has compiled nine common inverter problems and corresponding solutions.
1. No display on the screen? Check the DC input first.
Symptom: The inverter screen is black and no information is displayed.
Core cause: The inverter LCD screen is powered by DC power, and a black screen is often caused by an abnormal DC input.
Possible causes:
A. Insufficient module voltage: Single phase inverters typically operate between 100–500V and will shut down if the voltage falls below 100V. Voltage is affected by sunlight intensity, and insufficient sunlight can cause a black screen.
B. Wiring error: The PV input terminals are connected with the reverse polarity or mixed with other strings.
C. The DC switch is not closed: Verify the DC switch status.
D. Loose module connector: A loose connector in a series of modules can cause a circuit break.
E. Module short circuit: A short circuit in an individual module can affect the entire string.
Solution:
A. Use a multimeter to check the total DC voltage.
B. If there is no voltage, check the DC switch, wiring terminals, cable connectors, and module status in sequence.
C. Test multiple modules one by one to identify the abnormal string.
D. If the system suddenly goes black after a period of use and the above checks show no abnormalities, it may be a hardware failure and you should contact customer service immediately.
2. PV overvoltage alarm? Pay attention to the string voltage.
Symptom: The screen displays "PV overvoltage" and the inverter may shut down for protection.
Cause: Too many modules in series, causing the voltage to exceed the inverter's upper limit. This voltage increases, especially in winter when temperatures are low.
Solution:
A. Single phase inverter: Input voltage 100–500V, recommended string voltage 350–400V.
B. Three phase inverter: Input voltage 250–800V, string voltage recommended 600–650V.
This range ensures normal power generation in low light conditions while avoiding overvoltage alarms.
3. Isolation Fault? Check Insulation
Symptom: "Isolation Fault" appears, indicating substandard system insulation to ground.
Core Issue: The PV system's insulation resistance to ground is less than 2MΩ, posing a leakage risk.
Possible Causes:
A. Damaged insulation on the modules, cables, or inverter.
B. Water ingress or inadequate insulation on the terminals.
Solution:
A. Disconnect the grid and inverter, and check the resistance of each module, cable, and terminal to ground.
B. Replace damaged insulation components.
4. Leakage Current Fault? Disconnect power first to troubleshoot.
Symptom: "Excessive Leakage Current" appears, indicating the inverter may be shutting down for protection.
Solution:
Disconnect the PV array input and check for AC grid abnormalities.
B. Completely disconnect the DC and AC terminals and power off the inverter for at least 30 minutes.
C. If the problem resolves automatically, continue using the inverter; if not, contact customer service.
5. Grid Error? Pay attention to voltage and frequency.
Symptom: The "Grid Error" message appears, and the inverter cannot connect to the grid.
Cause: The grid voltage or frequency exceeds the inverter's acceptable range.
Solution:
A. Measure the grid voltage and frequency to confirm they are normal.
B. If the grid is normal but the error message persists, disconnect the DC and AC terminals and restart. If this still does not work, contact customer service.
6. Hardware Failure? Try powering on and off first.
Symptom: The "Hardware Failure" message appears, possibly involving the circuit board or power circuit.
Solution:
A. Disconnect the DC and AC terminals, power off for at least 30 minutes and restart.
B. If the problem persists, contact customer service to address the hardware issue.
7. Low Output Power? Troubleshoot from 10 aspects.
Symptom: Power generation is lower than expected, and the power output is not increasing.
Troubleshooting Key Points:
A. Check whether the module power meets the specification.
B. Adjust the module angle and orientation to optimize sunlight reception.
C. Clear dust and obstructions.
D. Ensure that the string voltage is within the inverter's operating range.
E. Match the voltage and power of multiple strings to avoid lag.
F. Ensure proper inverter heat dissipation to avoid derating due to high temperatures.
G. For dual channel MPPT inverters, ensure that the power input to each channel is appropriate.
H. Check the cable specifications and connector condition to avoid voltage loss.
I. Confirm that the AC switch has sufficient capacity.
J. Ensure the system installation layout is reasonable to avoid losses caused by excessive line lengths.
8. AC side overvoltage? Reduce line impedance
Symptom: The voltage on the inverter output side is too high, triggering protection or derating.
Cause: High grid impedance, resulting in increased generated voltage.
Solution:
A. Replace with thicker cables to reduce impedance.
B. Reduce the distance between the inverter and the grid connection point.
Most PV inverter faults can be resolved by carefully troubleshooting DC, AC, component, and wiring issues. In terms of routine maintenance, keeping components clean, arranged appropriately, and ensuring adequate ventilation and heat dissipation are key to avoiding frequent inverter failures. Xindun provides professional technical support to ensure stable and efficient operation of your PV system.
