A. Low output power
1. Fault phenomenon
The actual PV output power inverter is very less than what is expected in the performance, which eventually results in insufficient power output and, therefore, impelling less economic output of the whole system;
2. Cause Analysing
(1) Failure on PV module level such as PV modules damaged, some module in Shading, a lot dust on the PV panels may result in the reduction in power that it can emit, and accordingly, directly influence the Inverter real output power performance.
(2) Improper inverter parameter setting: e.g., the inverter's maximum power point tracking (MPPT) parameter setting is unreasonable, which may lead to the inverter not being able to accurately track the maximum power point of the PV modules, thus reducing the output power.
(3) The grid voltage is too high or too low: once the grid voltage exceeds the inverter's operating range, it automatically cuts down the output power in order to protect both itself and the grid equipment.
(4) Internal failure of the inverter: such as the burning of the power module of the inverter, poor heat dissipation, etc., which will cause the output power of the inverter to decrease.
3. Treatment method
(1) Check the PV module: Check damage, shading and dust accumulation and so on of the photovoltaic module. If there is something wrong, repair or clean it in time.
(2) Check the inverter parameter setting: Check if the MPPT parameter in the inverter is set properly and adjust it if needed.
(3) Check the grid voltage: Utilize a voltmeter to measure the grid voltage and ensure the grid voltage is within the working range of the inverter. If the grid voltage is abnormal, contact the power company in time to deal with it.
(4) Check the internal inverter: If you suspect the internal failure of the inverter, you should contact professional technicians for overhaul in time.
B. Output Periodic Fluctuation
1. Fault phenomenon
The output power of the photovoltaic inverter is periodically fluctuating, which may result in unstable voltage at the grid side and impact the normal usage of electrical equipment.
2. Possible causes
(1) Instability of the PV module output: When the PV module is influenced by cloud shade, the variation in shadow and other factors, this will make the power output of the PV module unstable, leading to periodic fluctuations in the output of the inverter.
(2) MPPT tracking instability of the inverter: If the MPPT tracking algorithm of the inverter is unstable, it may lead to the inverter not being able to accurately track the maximum power point of the PV modules, thus causing periodic fluctuations in the output power.
(3) Grid interference: If there is harmonic, voltage fluctuation and other interference factors in the grid, it will affect the output stability of the inverter, resulting in periodic fluctuation of output.
3. Treatment method
(1) Check the PV modules: try to avoid the PV modules from being affected by cloud cover and shadow changes.
(2) Inverter MPPT tracking algorithm check: the MPPT tracking algorithm in the inverter may not be good and needs an upgrade to improve the software version, which can be done on the existing inverter or completely change it with a different type.
(3) Check the grid interference: adopt a power quality analyzer to detect the harmonics and voltage fluctuation and other interference factors in the power grid and install the filter and other equipment for management if necessary.
Output distortion
1. Fault phenomenon
The output AC waveform of the PV inverter is distorted, which may cause damage to the power equipment and affect the power quality of the grid.
2. Possible causes
(1) Internal failure of the inverter: such as the power module of the inverter is damaged, the control circuit fails, etc., and the output waveform of the inverter will be distorted; (2) Grid interference: if there are harmonics, voltage fluctuations, and other disturbing factors in the grid, it will influence the output stability of the inverter and lead to the distortion of the output waveform.
(3) load imbalance in a PV generation system generates unbalance in an output current from the inverter which also causes wave-form distortion on an output, too;
C. Treatment Method
(1) The internal inversion checks any suspect about the inversion is due to some internal inversion faults that will be overhauling professionally and timely through calling for services with professional technician assistance.
(2) Check the grid interference: Use the power quality analyzer to detect the harmonic and voltage fluctuation and other disturbing factors in the grid, and install the filter and other equipments for treatment if necessary.
(3) Check the load balance: Ensure the load balance of the PV power generation system, if necessary, the load can be adjusted.
D.Fault alarm
1. Fault phenomenon
The fault alarm signal of the PV inverter will be output, and even system shutdown will be caused to affect power generation.
2. Possible causes
(1) Internal failure of the inverter: such as the damage of the power module of the inverter, failure of the control circuit, etc., which will cause the inverter to send out a fault alarm signal.
(2) PV module failure: including damage to PV modules, short circuit, open circuit, and so on, which will cause the inverter to send out a fault alarm signal. The abnormality of the grid: such as grid voltage too high or too low, abnormal frequency, and so on, will make the inverter send out a fault alarm signal.
3. Handling method
(1) Inverter internal check: When the inverter sends out a fault alarm signal, first of all, check the inverter display or indicator to determine the type and cause of the fault. Then, according to the type and cause of the fault, take corresponding treatment measures, such as replacing damaged parts and repairing faulty circuits.
(2) PV module check: check whether the PV module is damaged, short-circuited, open-circuited, etc., and repair or replace it in time if there is any problem.
(3) Check grid abnormality: If the inverter sends out a fault alarm signal due to grid abnormality, the power company should be contacted in time for processing.
E. Grid abnormality
1. Fault phenomenon
Abnormality such as too high or too low grid voltage detected by PV inverter and abnormal frequency may lead to inverter shutdown or power drop.
- Possible Causes
(2) Interconnection issues between the PV power generation system and the power grid: for example, loose connection lines and poor contact between the PV power generation system and the power grid will lead to abnormal parameters of the power grid.
(3) Inverter failure: for instance, damage to the grid monitoring module of the inverter, control circuit failure, etc., which will cause the inverter to misjudge the grid abnormality.
3. Handling methods
(1) contacting the power company: if the grid abnormality is detected by the inverter, it should contact the power company in time and understand the situation of the failure in the grid to coordinate with the power company for handling.
(2) Check the connection between the PV power generation system and the power grid: Check whether the connection line between the PV power generation system and the power grid is loose, poor contact, etc., and repair it promptly if there is any problem.
(3) Check the inverter: if you suspect that the inverter is faulty, you should contact professional technicians for overhaul in time.
F. Leakage current abnormality
1. Fault phenomenon
Abnormal leakage current detected by the PV inverter may lead to the shutdown of an inverter or triggering of the leakage protection device, influencing system safety.
- Possible causes
(2) Inverter inner failure: such as the destruction of the insulation monitoring module of the inverter and leakage of the power module. All these will lead to the abnormality of leakage current.
(3) Damages in cables: such as damage on the cable of the PV power generation system, insulation ageing, etc., which will further lead to increased leakage current.
3. Treatment method
(1) PV module grounding check: Check the looseness and poor contact of the PV module grounding line, and deal with it in time;
(2) Inverter internal check: If it is considered to be an internal failure of the inverter, it shall be overhauled in time by relevant professional technicians.
3) Check the cable: whether the cable of the PV power generation system is damaged or insulation aging, etc.; if there is any problem, it should be replaced in time.
G. Abnormal Insulation Impedance
1. Fault Phenomenon
The abnormal insulation impedance of PV inverter detecting may result in the shutdown of the inverter or triggering of insulation protection devices to endanger the safety of the systems.
2. Possible Cause(s)
(1) Poor insulation of PV modules: such as damage to the insulation layer of PV modules, moisture, etc., which will lead to a drop in insulation impedance.
(2) Inverter internal faults: such as damage to the insulation monitoring module of the inverter, poor insulation of the power module, etc., which will lead to abnormal insulation impedance.
(3) Poor insulation of cables: e.g., damage to the insulation layer of the cables of the PV power generation system, moisture, etc., which will lead to a drop in insulation impedance.
3. Treatment method
(1) Check the insulation of PV modules: Check whether the insulation layer of PV modules is damaged, damp, etc., and repair or replace it promptly if there is any problem.
(2) Check the inverter internal: If you suspect the inverter internal failure, you should contact professional technicians for overhaul in time.
(3) Check cable insulation: check whether the cable insulation of PV power generation system is damaged, damp, etc., and replace it promptly if there is any problem.
H. Abnormal PV voltage
1. Fault phenomenon
The PV inverter detects the abnormality of PV voltage, such as the voltage is too high, too low, or fluctuating, which may lead to inverter shutdown or output power drop.
2. Possible causes
(1) PV module failure: such as PV module damage, short circuit, open circuit, etc., which will lead to abnormal PV voltage.
(2) MPPT tracking failure of the inverter: If the MPPT tracking algorithm of the inverter fails, it is unable to track the maximum power point of the PV module accurately, leading to abnormal PV voltage.
(3) Influence of environmental factors: If the temperature, light intensity and other environmental factors change greatly, it will affect the output voltage of PV modules, thus causing abnormal PV voltage.
3. Treatment method
(1) PV module check: Check if the PV module is damaged, short-circuited, or open-circuited, and repair or replace it in time if there is any problem.
(2) MPPT tracking of inverter check: If the MPPT tracking algorithm of the inverter is faulty, try to upgrade the software version of the inverter or replace the inverter with one with better performance.
(3) Consider environmental factors: If environmental factors change significantly, you can take appropriate measures, such as adjusting the mounting angle of the PV modules, increasing heat dissipation equipment, etc., to minimize their impact on the output voltage of the PV modules.
I. No utility link
1. Fault phenomenon
The PV inverter is unable to detect the utility connection, which may cause the system unable to work normally or fail to send power to the grid.
2.Possible causes
(1) Grid failure: such as substation failure of the power company, line failure, etc., which will lead to interruption of utility power.
(2) Problems in connecting the photovoltaic power generation system with the grid: such as loose connection lines, and poor contact between the PV power generation system and the grid, which will cause the inability of the inverter to detect utility power connection.
(3) Failure of the inverter itself: such as damage to the grid monitoring module of the inverter, control circuit failure of the inverter, etc., as a result of which the inverter fails to detect the utility connection.
3. Handling method
(1) Contact the power company: If the inverter cannot detect the utility connection, you should first contact the power company to learn about the grid failure and cooperate with the power company to deal with it.
(2) Check the connection of the PV power generation system and the power grid: Whether the connection line between the photovoltaic power generation system and the power grid is loose, poorly contacted, and so on. Solve the problems timely if there exists one.
(3) Check the inverter: In cases of suspected inverter fault, overhaul should be conducted with the help of professionals in time.
J. AC voltage out of range
1. Fault phenomenon
The PV inverter detects that the AC voltage is out of the set range, which may cause the inverter to shut down or the output power to drop.
2. Possible causes
(1) Grid voltage fluctuation: e.g. power company's substation failure, line failure, etc., will lead to grid voltage fluctuation, thus making AC voltage out of the setting range of the inverter.
(2) Problems of connection between PV power generation system and grid: such as excessive impedance and poor contact of the connection line between PV power generation system and grid, which will lead to abnormal AC voltage.
(3) Inverter failure: damage to the voltage regulation module of the inverter, such as failure of the control circuit, etc., resulting in that the inverter fails to regulate the output voltage normally so as to make the AC voltage out of the setting range.
3. Handling methods
(1) Contact the power company: If the inverter detects that the AC voltage is out of range, it should contact the power company in time to learn about the grid failure and cooperate with the power company to deal with it.
(2) Inspect the connection between the photovoltaic power generation system and the power grid; check whether the connecting line between the photovoltaic power generation system and the power grid has too much impedance, poor contact, and so on; repair in time if there is something wrong.
(3) Inspection of inverter: For suspected failures of the inverter, it should be overhauled by contacting professional technical personnel in due time.
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