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PV voltage refers to the open circuit voltage of the series, that is, the positive and negative electrode voltage measured after the battery panels are connected in series. The reasons for low PV voltage may include too few connected boards in series, reverse connection of positive and negative electrodes in some series, loose terminals, poor contact, open circuit in series, etc.
Troubleshooting:
To measure the PV voltage of the string, the DC voltage gear of the multimeter is required. The red lead is connected to the positive pole and the black lead is connected to the negative pole. Read the display reading of the multimeter. If the reading is in the rated input range of the inverter and is a positive number, the PV voltage is normal.

Cause analysis:
Different inverters have different DC voltage input range, so the number of battery panels in series should be configured according to the DC voltage input range of the inverter, and the report of "PV voltage high voltage" is generally caused by too many battery panels in series, which exceeds the DC voltage range of the inverter.
Troubleshooting:
Check the parameters of the inverter and the input range of DC voltage, and then measure the open circuit voltage of the string (open circuit voltage refers to the voltage of the string when the inverter is not connected to the grid).

Cause analysis:
The inverter has the function of detecting the insulation impedance at the DC side. If the insulation impedance at the DC side is detected to be lower than 50K Ω, the inverter will report "PV insulation impedance too low fault". The possible causes include the cable breaking at the DC side, the moisture of the live exposed part, the leakage of the DC module, and the short circuit to the ground at the DC side of the inverter.
Troubleshooting:
Disconnect AC air switch and DC air switch; remove the positive and negative poles of DC measuring string with special MC4 disassembly wrench; ensure reliable grounding of component support With the megohm range of the multimeter, connect the red probe to the positive pole of the string and the black probe to the ground, read the impedance reading of each positive pole to the ground, then connect the red probe to the negative pole of the string, and read the impedance reading of each negative pole to the ground. If it is greater than 50K Ω, the inverter will judge that the insulation of the string is reliable, if it is less than or equal to 50K Ω, the inverter will judge that the insulation of the string is faulty, and the inverter will automatically switch on Protect and stop working, report "PV insulation impedance is too low".

Cause analysis: the mains voltage exceeds the normal grid connected operation voltage range of the inverter, and the grid voltage is too high, which will exceed the grid connected voltage upper limit set by the inverter factory (factory set voltage range 195vac ~ 253vac); generally, it occurs in the family distributed power station, and if the photovoltaic power generation users can not digest it locally, the remaining electricity will be connected to the grid, and the line impedance is too large in the process of connecting to the grid, resulting in the inverter output side power failure If the voltage is too high, the inverter protection will be off grid or load shedding. It is also possible that the voltage fluctuation range of the rural power grid itself is relatively large, and it is easy to exceed the upper limit of the inverter voltage, resulting in load shedding or off grid.
Exclusion method:
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 cable resistivity, the copper wire resistivity is much smaller than the aluminum wire resistivity, generally using copper wire; if the voltage of the rural power grid itself exceeds the grid connection voltage range of the inverter, the upper limit of the grid connection voltage of the inverter can be adjusted appropriately.

Cause analysis:
If the AC side is open, the inverter will not detect the voltage of the utility.
Exclusion method:
Remove the output port of the inverter, and measure the voltage (phase voltage) between the live line and the zero line of the user side of the output port with the AC voltage gear of the multimeter. If there is no 220 V AC, it is judged that there is no problem on the inverter side. It is the external AC side open circuit. It is necessary to check whether the air switch, knife switch, over-voltage and under voltage protector and other safety switches are damaged or open circuit.

Cause analysis:
The problem of power generation is related to many factors, such as weather, temperature, shelter, inverter, component orientation, component inclination, etc.
Investigation method:
Weather: haze, rainy days, cloudy days, bad weather will make the power generation of the system low.
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.
In terms of shielding: first check whether there are shielding objects in the surrounding environment, including nearby trees, power poles, water storage tanks of solar water heaters, drying clothes, bird droppings on the battery panels, and the front row of photovoltaic panels covering the back row. The MPPT tracking of photovoltaic inverter is like a barrel effect, so it is greatly affected by shielding. If one block is blocked, the conversion efficiency of the whole string will change Low, thus affecting the power generation of the system.
Module orientation: modules with different orientations cannot be connected to the same MPPT, which will affect the tracking of the core inverter in the photovoltaic system, thus affecting the power generation of the system.
Module inclination: pay attention to the installation inclination of the module should be the best angle of the local irradiation; different inclination angles, the conversion efficiency of photovoltaic panels are different at the same time, so when the solar irradiance is the strongest (generally 11:00 noon to 2:00 PM), the appropriate inclination angle of the module receives the most solar energy; different inclination angles of the power generation system will produce different peaks, so compare It can be found that the best inclination of the system is not the best inclination, and the power generation of the natural system is low.
PV panel reason: different brands of PV panels can not be connected to the same string and MPPT, especially the damaged PV panel will affect the power generation of the whole string, please replace the damaged string in time.
Inverter reason: if the inverter does not generate power when it reports a fault, the power generation will be affected. The DC open circuit voltage should be set in the appropriate range of the inverter. If the open circuit voltage of the distribution board is not within the MPPT voltage range of the inverter, the power generation efficiency of the inverter will be affected, thus affecting the power generation of the photovoltaic system.
Power grid reason: power grid fluctuation occurs from time to time, and ensuring the quality of power grid is an important condition to ensure the normal power generation of inverter. Therefore, pay attention to the voltage fluctuation and frequency fluctuation of power grid, which will affect the power generation of inverter, and even make the inverter report fault. The nearby high-power capacitive load will also affect the quality of power grid, thus affecting the power generation of inverter.