What to do if there is a fault in a photovoltaic power plant?

Failure analysis: There is no DC input, the inverter LCD is DC powered.

Possible causes:
(1) Insufficient component voltage. Inverter operating voltage is 100v to 500v, below 100v, the inverter does not work. The module voltage is related to solar irradiance.
(2) The PV input terminal is reversed. The PV terminal has positive and negative poles, which should correspond to each other and not be reversed with other groups.
(3) The DC switch is not closed.
(4) When the components are connected in series, one of the connectors is not connected properly.
(5) One component is short-circuited, causing the other components not to work either.

Solution:

Measure the DC input voltage of the inverter with a multimeter voltage class. When the voltage is normal, the total voltage is the sum of the voltages of each group. If there is no voltage, test the DC switch, terminals, cable connectors, components, etc. in turn to see if they are normal. If it is a multi-way component to be tested separately and individually connected.

If the inverter is used for a period of time and no cause is found, the inverter hardware circuit is faulty, please contact the company after-sales.

Fault analysis: The inverter and the grid are not connected.

Possible causes:
(1) The AC switch is not closed.
(2) The inverter AC output terminal is not connected.
(3) The upper row of inverter output terminals on the connection line is loose.

Solution:
Use a multimeter voltage file to measure the inverter AC output voltage, under normal circumstances, the output terminals should have 220V or 380V voltage, if not, test the terminals in turn whether there is loose, whether the AC switch is closed, whether the leakage protection switch is disconnected.

Failure analysis: DC voltage is too high alarm.

Possible cause: The number of components in series is too high, causing the voltage to exceed the voltage of the inverter.

Solution:
Because of the temperature characteristics of the components, the lower the temperature, the higher the voltage. The input voltage range of single-phase string inverter is 100-500V suggesting that the voltage after string is between 350-400V, and the input voltage range of three-phase string inverter is 250-800V suggesting that the voltage after string is between 600-650V. In this voltage range, the inverter is more efficient and can generate electricity in the morning and evening when the irradiance is low, but without the voltage exceeding the upper limit of the inverter voltage and causing an alarm and shutdown.

Fault analysis: PV system insulation resistance to ground is less than 2 megohms.

Possible causes:
Solar modules, junction boxes, DC cables, inverters, AC cables, terminals and other places where there is a wire to ground short circuit or insulation layer damage. PV terminals and AC wiring shell loose resulting in water ingress.

Solution:
Disconnect the grid, inverter, check the resistance of the wires to ground of each component in turn, find out the problem point and replace.

Failure analysis: The leakage current is too large.

Solution:
Remove the PV array input, then check the peripheral AC grid. Disconnect all DC and AC terminals, let the inverter blackout for more than 30 minutes, if it recovers by itself, continue to use, if not recover contact after-sales technical engineer.

fault 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 grid is normal, it is the inverter detection circuit board power generation fault, please disconnect all the DC and AC terminals, let the inverter power outage for more than 30 minutes, if you can restore yourself to continue to use, if not, contact the after-sales technical engineer.

Failure analysis: The inverter circuit board, detection circuit, power circuit, communication circuit and other circuits are faulty.

Solution:
If the inverter is faulty, please disconnect the DC and AC terminals and let the inverter power down for more than 30 minutes, if you can recover it yourself, continue to use it, if not, contact the after-sales technical engineer.

Possible causes:
Many factors affect the output power of photovoltaic power plants, including the amount of solar radiation, the tilt angle of the solar cell module, dust and shadow blocking, the temperature characteristics of the components.

Due to improper system configuration and installation, the system power is small, common solutions are:
(1) Test the power of each module for adequacy before installation.
(2) Adjust the mounting angle and orientation of the modules.
(3) Check if there are shadows and dust on the modules.
(4) Check that the voltage is within the voltage range when the modules are connected in series, too low a voltage will reduce the efficiency of the system.
(5) Before installing multiple strings, check the open circuit voltage of each string, the difference should not exceed 5V, if the voltage is found to be incorrect, check the wiring and connectors.
(6) Installation can be accessed in batches, each group of access to record the power of each group, the power difference between the strings does not exceed 2%.
(7) The installation place is not well ventilated, the heat of the inverter does not spread out in time, or it is directly exposed to the sunlight, causing the temperature of the inverter to be too high.
(8) The inverter has double MPPT access, and the input power of each way is only 50% of the total power. In principle, the designed installed power of each way should be equal, if only connected to the MPPT terminal of one way, the output power will be halved.
(9) Poor contact of cable joints, too long and too thin cable diameter have voltage loss and finally cause power loss.
(10) PV plant grid-connected AC switch capacity is too small to meet the inverter output requirements.

Possible causes:
Grid impedance is too large, photovoltaic power generation user side can not be digested, and transmission out due to impedance is too large, resulting in the inverter output side voltage is too high, causing the inverter protection shutdown or derate operation.

Common solutions are:
(1) Increase the output cable, because the thicker the cable, the lower the impedance.
(2) The shorter the cable, the lower the impedance.

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