In the photovoltaic power station, the power of a large number of modules must be gathered together to enter the inverter, which must rely on the cable and photovoltaic energy connector. The photovoltaic energy connector is the key part of the interconnection between modules, combiner box, controller and inverter in the photovoltaic power generation system.

By the end of September 2018, China's cumulative installed photovoltaic capacity was about 133gw, ranking first in the world. At present, there are about 530 million sets of connectors in domestic photovoltaic power stations based on the consumption of 4000 sets of 1MW. From the perspective of risk, it means that there are at least 530 million risk points that need the attention of power station owners. However, in the stage of power station design, construction and operation and maintenance, the photovoltaic energy connector is often ignored. The reason is that people do not pay enough attention to it.

Photovoltaic system has been exposed to wind, rain, sun and extreme temperature changes for a long time. Photovoltaic energy connector must be able to adapt to these harsh environments. They should not only be waterproof, high temperature resistant and weather resistant to ultraviolet rays, but also be touch protected, high current carrying capacity and efficient. At the same time, low contact resistance is also an important consideration. All of these must run through the whole life cycle of photovoltaic system, at least 25 years.

(1) Shell insulation material

The application environment of photovoltaic energy connector is generally very harsh, from coastal saline land to plateau desert and other terrain, from hot equator to cold high latitude areas, as well as solar radiation, rain and snow, wind and sand and other perennial erosion. The weatherability, heat resistance, flame retardancy, mechanical properties, insulation properties and other aspects of the shell insulation materials are very good, It can only be used for 25 years to ensure that the copper core inside is insulated from the outside.

(2) Seal

Inside the photovoltaic energy connector are the plug-in copper core and the cable copper core, which have no anti-corrosion function. The connector is required to keep the copper core isolated from the outside world. The on-board connector is also connected with the inverter (or controller), so the sealing function of the inverter should be ensured, so the sealing function of the connector should be very reliable. In addition, the sealing screw should be tightened during installation.

(3) Contact resistance

According to the latest international standard IEC 62852 of photovoltaic energy connector, the increment of contact resistance after male and female plug-in should not be greater than 5 m Ω or the final value should be less than 150% of the initial value. Using high-quality photovoltaic energy connector, the power consumed on the connector is less than one ten thousandth of the total power of the system, and the power consumed by poor quality photovoltaic energy connector is more than 30 times that of high-quality photovoltaic energy connector. The root cause of the failure of the photovoltaic energy connector and the fire: in the case of through flow, the increase of the contact resistance of the photovoltaic energy connector leads to the increase of the temperature rise, which is beyond the temperature range of the plastic shell and metal parts. The contact resistance is mainly related to the material and size of copper core. Different brands of photovoltaic energy connector have different specifications. It is recommended not to mix them.