Replacing MC4 solar connector without crimping or cutting wire

[gordon2]

Here I describe how I replaced a broken MC4 Solar Panel connector without cutting the wire or crimping. This technique is not the recommended method, will likely void any warranty, and will only work if the wire and pin are undamaged.

Although MC4 connectors are standardized, there is enough variation due to manufacturing tolerances so that one brand does not always work well with another. That was the case for me, when I tried to use a Renogy MC4 connector with a different brand of pre-made cable extension. The connectors were very difficult to connect or disconnect, even with the MC4 tool. The result was that I broke off one of the locking tabs.


So I replaced the broken connector and also replaced the connectors on the pre-made cable with matching Renogy MC4 connectors using this technique which leaves the original wire crimp and wire length unchanged.

For a description of the different parts of the connectors see the exploded views at https://en.wikipedia.org/wiki/MC4_connector

1. Unscrew the end cap, slide it and the strain relief and compression sleeve up the wire a ways to get it out of the way.


Inside the connector there is a metal locking ring that holds the pin in place.


Using a fine blade cutting wheel, carefully start to cut through the plastic at the base of the end cap’s male threads on the main connector.


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Cut the plastic to just shy of the metal locking ring all the way around until you can separate the threaded portion.


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I used a Dremel with the Dremel EZ-Lock cutting kit.



(see next message)

[gordon2]

(Continued from prior message)
Once the threaded portion is cut off, carefully open the locking ring where it is split, and remove it.




At this point the pin is free and can be removed from the connector.

Slid the original strain relief, compression sleeve and end-cap off and replace with the same parts from the new connector in the same order and orientation.



Insert the pin into the new connector until you hear a click and it locks.


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Slide the strain relief and compression sleeve in place.



Screw on the end-cap and tighten using the MC4 tool. Watch the wire as you use the MC4 tool to tighten the end-cap so the wire does not twist.

[gordon2]

Good as new!

[David B.]

Thank you Gordon for the detailed pictures and well explaination of the repair. I hope I’ll be able to remember where to find this info in the future if needed.
Dave & Paula

[gordon2]

Originally Posted by David B.

... I hope I’ll be able to remember where to find this info in the future if needed.
Dave & Paula

I made my own cables to start with using online guides. So the reassembly part of my post is the same regardless, except that I did not need to crimp the wires. You can find info on proper crimp techniques and tools online also. A good crimp tool is very much preferred.

There are a number of online how-tos for installing MC4 connectors on bare wires so just google when you get ready. He is a decent video for one example:

https://www.youtube.com/watch?v=oHpYEhgO_gE