What are MC4 Connectors?

MC4 connectors are commonly used for connecting solar panels. MC stands for Multi-Contact, the original manufacturer. 4 stands for the 4 mm diameter contact pins. Earlier MC3 connectors with 3 mm pins were used, but have been discontinued in 2016. It is easy to connect strings of solar panels together by pushing compatible connectors from adjacent panels by hand. But, to avoid accidental disconnection, a tool is required to disconnect them. To avoid the danger of cross-mating, connectors from same type and brand have to be used. While the original versions were rated for 600V, newer versions of MC4 connectors are rated for 1500V, allowing creation of longer series strings of solar panels.

Here is a dismantled view of female and male MC4 connectors with the metallic pins on one side. These connectors have ultra-violet protection and can withstand rain, sun and dust.

This is the MC4 spanner wrench tool for connecting and disconnecting the MC4 solar connector. It has been mentioned that using your fingers or other tools to disconnect them might cause damage. Disconnection should not be attempted in a loaded condition, especially for high voltage installations. Safety gloves have to be used while handling multiple solar panels in strings.