Cause Analysis:If the AC side is disconnected, the inverter will not be able to detect the voltage of the mains.
Method of exclusion:Remove the output port of the inverter, and use the AC voltage range of a multimeter to measure whether the voltage (phase voltage) between the live wire and the neutral wire on the user side of the output port is 220V. If there is no AC 220V, it is judged that there is no problem on the inverter side If the external AC side is open circuit, it is necessary to check whether the safety switches such as air switch, knife switch, overvoltage and undervoltage protector are damaged or open circuit.
PV system power generation is low
Cause Analysis:The power generation problem is related to many factors, weather, temperature, shading, inverter, component orientation, component inclination, etc.
Check method:Weather: haze, rainy days, cloudy days, and bad weather will make the power generation of the system low.
In terms of temperature: photovoltaic panels have the best working temperature, so too high or too low temperature will lead to low conversion efficiency of the panels, resulting in low power generation of the photovoltaic system.
Occlusion: Check the surrounding environment for obstructions, including nearby trees, utility poles, storage tanks of solar water heaters, drying clothes, bird droppings on battery panels, front row of photovoltaic panels covering the back row, etc. The MPPT tracking of the inverter is like the barrel effect, so it is greatly affected by occlusion. If a block is occluded, the conversion efficiency of the entire string will be reduced, thereby affecting the power generation of the system.
Component orientation: Components with different orientations cannot be connected to the same MPPT, which will affect the tracking of the core inverter in the photovoltaic system, thereby affecting the power generation of the system.
Module inclination: Note that the installation inclination of the module should be the best angle for the local irradiation; different inclinations have different conversion efficiencies of photovoltaic panels at the same time, so when the solar irradiance is the strongest (generally 11 noon at noon) : 00 to 2:00 pm), the inclination angle of the appropriate module receives the most solar energy; different inclination angle power generation systems will produce different peaks, and by comparison, it can be found that the optimal inclination angle of the system is not the optimal inclination angle. Power generation is low.
Photovoltaic panel reasons: PV panels of different brands cannot be connected to the same string and MPPT. Note that damaged photovoltaic panels will affect the power generation of the entire string. If you encounter damaged strings, please replace them in time.
Inverter reason: The inverter does not generate electricity when it reports a fault, which will affect the power generation. The DC open circuit voltage should be set in the appropriate range of the inverter, and the board is not properly matched. For example, the open circuit voltage of the board is not the MPPT voltage of the inverter. Within the range, it will affect the power generation efficiency of the inverter, thereby affecting the power generation of the photovoltaic system.
Power grid reasons: power grid fluctuations occur from time to time, ensuring the quality of the power grid is an important condition to ensure the normal power generation of the inverter, so pay attention to grid voltage fluctuations, frequency fluctuations, etc., which will affect the power generation of the inverter, and even cause the inverter to report a fault. Nearby high-power capacitive inductive loads will also affect the quality of the power grid, thereby affecting the power generation of the inverter.
The grid voltage is too high
Cause analysis: The mains voltage exceeds the voltage range of the inverter’s normal grid-connected operation. If the grid voltage is too high, it will exceed the inverter’s factory-set grid-connected voltage upper limit (the factory-set voltage range is 195Vac~253Vac); it generally occurs in household distribution. If the photovoltaic power generation users cannot digest the surplus electricity locally, the line impedance is too large during the online process, causing the voltage on the output side of the inverter to be too high, causing the inverter protection to be disconnected from the grid or run at reduced load. It is also possible that the voltage fluctuation range of the rural grid itself is relatively large, and it is easy to exceed the upper limit of the inverter voltage, resulting in load reduction or off-grid.
Method of exclusion:Increase the output cable, the thicker the cable, the lower the impedance; the inverter is installed as close as possible to the grid connection point, the shorter the cable, the lower the impedance; change the resistivity of the cable, the resistivity of copper wire is much smaller than that of aluminum wire, generally Use copper wire; if the voltage of the rural grid itself exceeds the grid-connected voltage range of the inverter, the upper limit of the grid-connected voltage of the inverter can be adjusted appropriately.
Insulation resistance is too low
Cause Analysis:The inverter has the function of detecting the insulation resistance of the DC side. When the insulation resistance of the DC side is detected to be lower than 50kΩ, the inverter will report “PV insulation resistance is too low fault”. The DC components are leaking, and the DC side of the inverter is short-circuited to ground.
Troubleshooting:Disconnect the AC circuit breaker and the DC circuit breaker; use the special MC4 dismantling wrench to remove the positive and negative poles of the DC measurement string; ensure that the component bracket is reliably grounded; Read the measured positive-to-ground impedance reading of each channel, then connect the red test lead to the negative pole of the string, and then read the negative-to-ground impedance reading of each channel. If it is greater than 50kΩ, the inverter judges that the insulation of the string is reliable, less than or equal to 50kΩ, the inverter judges that there is a problem with the insulation of the string, the inverter will automatically protect and stop working and report “PV insulation resistance is too low”.
PV voltage too high
Cause Analysis:Different inverters have different DC voltage input ranges, so the number of solar panels in the string should be configured according to the DC voltage input range of the inverter, and the report “PV voltage high voltage” is generally due to the solar panels of the string. The number is too large, which is caused by exceeding the DC voltage range of the inverter.
Troubleshooting:Check the parameters of the inverter, the input range of the DC voltage, and then measure the open-circuit voltage of the string (the open-circuit voltage refers to the voltage of the string when the inverter is not connected to the grid).
PV voltage too low
PV voltage refers to the open circuit voltage of the string, that is, the positive and negative voltages measured after the solar panels are connected in series. On the contrary, the terminal is loose and the contact is poor, and the string is disconnected.
Troubleshooting:To measure the PV voltage of the string, the DC voltage level of the multimeter is required. The red test lead is connected to the positive electrode, and the black test lead is connected to the negative electrode. Read the displayed reading of the multimeter. If the reading is within the rated input range of the inverter and is a positive number, the PV voltage is normal. .
Cause Analysis:There is no communication between the collector and the inverter; the collector is not powered on: the APP scans the serial number of the inverter; the installation position signal problem; the internal reason of the collector;
Troubleshooting:Check whether the 232 interface DIP switch is turned on; check whether the 232 interface is in contact with the collector; check whether the data communication of the inverter 232 interface is normal;
Scan the serial number of the collector, or manually enter the serial number and check code of the collector; check whether the installation location is blocked by the signal, or the WiFi collector cannot receive the router signal, and the GPRS is installed in the local without the network signal of the internal traffic card operator (Telecom traffic card cannot be used); observe the flashing light of the collector. If the external conditions are no problem, the collector does not have any connection response, which can be considered as an internal fault of the collector.
DC draw arc
Cause Analysis:Arc pulling occurs because the strings form a loop and there is current output, so arcing occurs. The possible reason is that the inverter is working and the strings are directly inserted and removed, or the positive and negative poles between the strings are short-circuited, and the positive and negative poles are reversed. The number of strings connected in series is unbalanced, etc.
Troubleshooting:Before plugging and unplugging strings, check that the inverter has been normally closed before plugging and unplugging. The inverter has current input in the working state, and the operation of plugging and unplugging strings will cause arcing phenomenon; check whether there is a positive or negative short circuit in the strings. Check whether the positive and negative of the strings are reversed, and then connect them to the inverter. When the strings with opposite polarities are connected to the same mppt, it is equivalent to connecting two strings to form a short-circuit arc; The number of solar panels connected in series is inconsistent, and in the same mppt, there will be perfusion between the strings, and arcs will be formed when the strings are inserted and removed.