Photovoltaic connectors, also known as MC connectors, in the photovoltaic system, connectors account for a small percentage, but many links need to be used, such as junction boxes, convergence boxes, modules and inverters between the cable connection are required. Many construction personnel do not know enough about the connector, due to the connector problem caused by power plant failure can be a lot, in July 2016 'solarbankability' released another report "review and analysis of factors affecting photovoltaic power generation" report, in the power plant TOP20 impact factors, connector damage or Loss of power generation due to burnout ranked 2nd.

Caused by photovoltaic connector burnout, in addition to the quality of the connector itself, another very important reason is that the construction is not done, resulting in a false connection of the connector, which triggered the DC side of the pull arc, which in turn caused the fire. Problems caused by the connector are: increased contact resistance, connector heating, shortened life, connector burnout, string power failure, junction box failure, component leakage and other problems, resulting in the system does not work properly, affecting the efficiency of power generation.

A few days ago, a customer said that the working status of a 25KW inverter he made recently was not normal and the power generation was low, and requested an analysis of the reason.

This 25kw inverter has 2 MPPTs, one connected to 2 strings, the other to 3 strings, connected to 320 crystalline silicon modules, the connection method is 18 strings 3 parallel + 16 strings 2 parallel.

The voltage of PV1 is 611.5V, the voltage of PV2 should be around 688V under normal circumstances, but the actual voltage of PV2 is only 315.9V, a difference of nearly 372V, so we consider that there is a problem with the wiring on the module side (a short circuit may have occurred in part), and we need to We need to go to the site to investigate the cause.

After-sales service engineers to the scene found that the inverter terminal has been burned, after careful on-site investigation, it is determined that due to the construction of the irregular crimping (yellow circle inside the joint), the joint is not done, false connection fire triggered arc, resulting in cable burn and inverter terminal burn.

In the entire PV system DC side voltage is usually as high as 600-1000V, once the PV module joints loose, poor contact, it is very easy to cause DC arcing phenomenon. DC pull arc will lead to a sharp increase in temperature of the contact part, the continuous arc will produce a high temperature of 1000-3000 ℃, and accompanied by high temperature carbonization of the surrounding devices. The lesser melted insurance, cable, the heavier burned equipment caused by fire.

Photovoltaic connectors are not standardized crimping is mainly due to the field tools and operating experience gap, resulting in poor crimping quality, the main problem is the cable copper wire bending, part of the copper wire is not crimped into and crimped part of the cable insulation layer.

After the string is done to the PV terminal of the inverter, try to use the original inverter with the PV connector, because this is paired with the PV terminal on the inverter, the correct crimp, then a good match, low contact resistance, low heat generation, while the temperature is lower, more reliable and safe operation.