connectors are single-contact electrical connectors commonly used for
connecting solar panels. MC4s allow strings of panels to be easily constructed
by pushing the connectors from adjacent panels together by hand, but require a
tool to disconnect them to ensure they do not accidentally disconnect when the
cables are pulled. The MC4 and compatible products are universal in the solar
market today, equipping almost all solar panels produced since about 2011.
Originally rated for 600 V, newer versions are rated at 1500 V, which allows
longer strings to be created.