To understand why matching different types of connectors can cause this problem, it is important to realize that there is no universal PV connector standard. Each product manufacturer designs and manufactures PV connectors according to its own specifications. The housings from different suppliers are made of different materials. The electrical contacts are made of dissimilar metals; there are no standard product dimensions or tolerances. These differences can cause malfunctions, and some of them can cause fires.

      For a long time, industry experts have been aware of the problems associated with the mating of incompatible PV connectors. Incident investigators and first responders have recorded these failures on site. The test laboratory personnel have studied the failure modes and root causes of the connectors. Trade publications and trainers were inspired by this issue and shared best practices.

      The problem still exists, partly because of misleading advertising. For manufacturers of module or module-level power electronic equipment, their photovoltaic module connectors are usually referred to as "MC-4 compatible" or similar products. Unfortunately, the "compatibility" of the connector is actually meaningless. Of course, you can actually plug two "compatible" connectors together. However, the nationally recognized testing laboratory has not yet evaluated and verified the quality, reliability and safety of this electrical connection.