MC4 Connectors?

MC4 connectors are water resistant at best, I had some that didn't seal around the wire at all. In the long run if you are looking for waterproof get rid of the MC4 and go to a junction box that seals well. A little water isn't going to hurt anything in the short run and may cause some corrosion in the long run so its best to do what you can to seal out the water but don't worry over it. If nothing else use as small of a connector as you can and then seal connector with marine grade adhesive shrink tube. I replaced the faulty MC4 connectors on 2 lines of my solar panels, hooked them together and called it a day.

Yes, I've been wondering how water "proof" mc4's are? I will be installing a combiner box, but I still need to extend the panel cables to the box. I imagine some tightly wound electrical tape should help. I could always re-do it, once or twice a year, to be safe. no biggie. I'll be inspecting things regularly, anyway.

MC-4 connectors are quick and easy but I wouldn't use them on an RV roof. They don't seal well enough. Use marine grade shrink tubes (the kind with melt glue inside). Heat them until the glue flows out of the ends. West Marine is a good source. I guess maybe you could put a real large one over the outside of an MC-4 but it's easier to use crimp-on butt connectors. Use a shrink tube over each wire connection and then a larger one over the whole cable joint. If you do it this way, be sure to keep track of your polarity. -Mark.

jrnymn7 wrote:
Yes, I've been wondering how water "proof" mc4's are? I will be installing a combiner box, but I still need to extend the panel cables to the box. I imagine some tightly wound electrical tape should help. I could always re-do it, once or twice a year, to be safe. no biggie. I'll be inspecting things regularly, anyway.

Don't waist your money on MC4 for this. Butt connectors will work just fine after all it's just 12 volt and even less than that coming from one solar panel. Forget the electrical tape and use adhesive shrink tube, a kit of shrink tube can be picked up at Harbor Freight for under $9. Make sure its the Marine/adhesive as they have both kinds in a kit.

Thanks, Muddy,

yeah, I already ordered four 5' cables with mc4 on one end only. If they become troublesome, I will do as you suggest, and simply butt the cables together.