A: A: Possible causes:
1. If the DC connector is not inserted firmly, the contact resistance of the conductive part of the male and female head is too high, and the current will generate heat and cause ablation and melting;
2. Although the DC connectors of different brands can be inserted normally, the size and tolerance of the connectors will have large deviations, the contact resistance of male and female heads is too large, and the IP protection level is reduced;
3. The male and female head metal pins and pins are not standardized, only a part of the wire core is crimped, or the length of the wire core is not enough, or the wire core is not firmly pressed, or the wire core is wrapped with insulation layer;
4. Part of the project design is not considered properly, and there are some redundant PV panels. The current flowing through the joint exceeds its rated current after the excess PV panels are connected;
5. The construction process is not standardized. After the series connection, the positive and negative poles are reversed, and connected to inverter without polarity detection

Solutions:
1. Improve the electrical safety awareness of the construction personnel, do not pull out the connector during the operation, and fully lock the connector when installation;
2. Strengthen the skill training of construction personnel, use professional tools to improve the quality of male and female pin and pin core crimping;
3. The male and female connectors must use the original connector provided by INVT, and do not mix different brands of connectors;
4. If there are redundant PV panels that need to be connected to other series, it is recommended to consult the technical personnel of the inverter manufacturer first;
5. Before connecting the PV panel strings to the inverter, it is necessary to use a multimeter to measure whether the polarity is correct, whether the open circuit voltage is normal, whether the positive and negative poles are short circuited to the ground, and then connect the inverter if there is no problem;