Analysis:

PV voltage low means the string’s voltage is low,may cause being wrong positive, negative connection, loose connection, or no connection of the panels.

Investigation:

Need to set multimeter to voltage, use the red pen to connect to positive electrode, use the black pen to connect to negative electrode, read the multimeter, if the voltage is in voltage range and it is positive, we can say the PV voltage is normal.

Analysis:

Different inverters have different DC input voltage range, so the connected solar panels would be set based on input DC voltage, basically “PV high voltage ” is caused by connection of too many panels.

Investigation:

Check the inverter’s setting, DC input voltage range, then check the string’s open circuit voltage.

Analysis:

inverter has a function which can test DCinsulation resistance, check if the DC side is lower than 50kΩ, it will give analarm as “PV insulation low” may be cause by damaged DC cable, wet exposed cable, DC components electricityleakage, inverter DC side short circled on the ground

Investigation:

disconnect AC air breaker and DC air breaker.

Use MC spanner to dissemble DC side positive andnegative electrode.

Make sure the racks have ground connection(Essential)

(Use the multimeter set to resistance, use the red pen to test positive electrode, black pen to test the ground connection, read each way’s positive to ground’s resistance) (then use the red pen to connect to negative electrode and read the resistance between negative electrode and ground, if it is larger than 50kΩ then may think the inverter can judge thestring’s insulation, if the number is less or equal to 50kΩ, then the inverter’s insulation is down, the inverter will automatically to self protection and stop working, give the error as “low insulation resistance”).

Analysis: 

grid voltage is exceeding inverter voltage range,normally is exceeding the highest setting voltage(factory setting is from195Vac-253Vac)

For General residential power plants, once the clients cannot use all the solar energy, the rest will be put to grid, as the resistance is very high, that may cause the output side of inverter, high voltage will lead to inverter offline.

Investigation:

 use large input cable, as the larger cable is the smaller resistance.

Inverter is closer to grid, shorter cables and less resistance.

Change the resistance rate, copper has less resistance rate than aluminum, so generally use copper cable.

If the inverter is connected to agriculture grid which has higher voltage than inverter’s voltage limit, you can slightly adjust the voltage limit.