MC4 connector incompatibility?


New member

I'm in the process of hooking up a pair of Grape Solar panels to an extension cable from Renogy. I cannot get the male end of the Renogy to engage with the female end of the Grape cable. The fit is too tight. All other combinations work (Grape male into Renogy female is OK, Renogy male into Renogy female is OK, Grape male into Grape female is OK).

I think I can probably cut one or both of the snap clips off the Renogy male end but that's super hokey.

I haven't yet called the manufacturers as they'll likely say it's the other guy's fault... Any suggestions?

(See pic.)




New member
Quick note, I have called both Grape and Renogy and both said they've never heard of it before. Grape at least suggested getting one of their extension cables to replace the Renogy (obvious and logical), but Renogy tech had no suggestions.


Expedition Leader
I've heard there are issues with counterfeit connectors in the market - perhaps that is the reason. Have you tried putting some dielectric grease compound on it? Might help - worth trying...


I've never had such issues.

Everything MC4 always works with MC4

Some are more snug than others, but they have all, always worked for me.


New member
Hi Folks,

These are the connectors supplied from the manufacturer, but I assume they're not the OEM of the plugs themselves. As it turns out, it was the fit of the clip legs on the male (Renogy) plug into the female receptacle slots (Grape) -- the clip legs were too wide / receptacle slots too narrow. I filed some material off the width of the legs and it's all happy town now. The Renogy legs were ~7.15 - 7.20 mm wide, the Grape slots were about 6.9mm wide (slightly harder to measure the internal width at that small size, so I'm only going to 1dp). Not gonna fit in there! I haven't found a spec for what that dimension should be, but that was the issue.



If you care enough, order a pair of standalone terminals from a quality supplier as if you were going to crimp them yourself.

The mass-market vendors are famous for cheaping out everywhere they (think they) can get away with it.

From online reputation I'm guessing Grape is the culprit.
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