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Common faults and solutions of photovoltaic power stations
Date:2019-12-16
 With the popularity of photovoltaics, more and more people are investing in photovoltaic power stations. Today, I will share some information about the possible failures and solutions in the daily operation of photovoltaic power stations, and provide a reference for project developers or owners.
 
1.PV overvoltage
Failure analysis: DC voltage is too high
Possible cause: Too many components are connected in series, causing the voltage to exceed the inverter voltage.
Solution: The lower the temperature, the higher the voltage due to the temperature characteristics of the component. The input voltage range of single-phase string inverter is 100-500V. The recommended voltage after stringing is between 350-400V, and the input voltage range of three-phase string inverter is 250-800V. The recommended voltage after stringing is 600- Between 650V. In this voltage range, the inverter has a high efficiency and can generate electricity when the irradiance is low in the morning and evening, but the voltage will not exceed the upper limit of the inverter voltage, causing an alarm and shutdown.
 
2.Isolate the fault
Failure analysis: The insulation resistance of the photovoltaic system to ground is less than 2 megohms.
Possible cause: The solar module, junction box, DC cable, inverter, AC cable, terminal block and other places have short wires to ground or the insulation is damaged. Loose PV terminal blocks and AC wiring housings cause water ingress.
Solution: Disconnect the power grid, inverter, and check the resistance of each component wire to ground in order to find the problem and replace it.
 
3. Leakage current fault
Failure analysis: too much leakage current
Solution: Remove the PV array input, and then check the surrounding AC grid. The DC and AC terminals are all disconnected, and the inverter is powered off for more than 30 minutes. If it recovers, continue to use it. If you cannot recover, contact the after-sales technical engineer.
 
4. Grid error
Failure analysis: The grid voltage and frequency are too low or too high.
Solution: Use a multimeter to measure the grid voltage and frequency. If it exceeds, wait for the grid to return to normal. If the power grid is normal, the inverter detects the power failure of the circuit board. Please disconnect both the DC terminal and the AC terminal, and power off the inverter for more than 30 minutes. If you can resume using it by yourself, contact the after-sales technical engineer .
 
5.Inverter hardware failure
Failure analysis: Inverter circuit board, detection circuit, power circuit, communication circuit and other circuits are faulty.
Solution: If the inverter has the above-mentioned hardware failure, please disconnect both the DC terminal and the AC terminal, and power off the inverter for more than 30 minutes. If you can recover it, continue to use it. If you cannot recover, contact the after-sales technical engineer.
 
6.AC side overvoltage
Probable cause: The grid impedance is too large, and the photovoltaic power generation user side cannot digest it. When the impedance is transmitted, the voltage on the inverter output side is too high, causing the inverter protection shutdown or derating operation.
Common solutions are:
(1) Increase the output cable, because the thicker the cable, the lower the impedance.
(2) The inverter is closer to the grid connection point. The shorter the cable, the lower the impedance.
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