Module has one brand of MC4-type connector, my extension cable has another. Can I plug them together?

Plain explanation

There is no single international design standard for PV connectors, so 'MC4-type' plugs from different makers can differ inside even if they look the same. Stäubli, the maker of the original MC4, says cross-mating is not recommended and may lead to severe, costly damage, and cites IEC 60364-7-712:2017: male and female connectors shall be of the same type from the same manufacturer. The UK industry body BEAMA warns that mixing look-alike connectors can cause poor contact pressure, higher resistance, overheating, arcing or fire. Fit matching connectors with the maker's crimp tool, and check your national code.

Steps from the source

1. Identify the connector make and type on the module (label/datasheet)
2. Use the same make and type on the mating cable
3. Crimp with the connector maker's specified tool
4. Check your national code for PV connector rules

"Cross-connections and cross-mating components are not recommended and may lead to severe, costly damage."

Word for word from the source.

Source

Where installers ask this

• All MC4 connectors are not the same (r/diySolar)
• reddit.com/r/solar/comments/1t5wek7/problem_with_mc4_type_connectors_that_were/

General guidance based on the manufacturer's manual or the named source. Always follow the current manual for your exact model and your national code. DC and AC electrical work is for qualified installers only. Not affiliated with or endorsed by any brand named; trademarks belong to their owners.