SMK or MC4

Lion, excellent questions, which unfortunately don't have a black and white answer, nor a short answer.

None of the wires altE offers are tinned. Likewise, the cables coming off your solar panels also are not tinned. This is an age old dilemma for boaters, tinned wire is definitely best for boats, but no one I know of makes tinned wire with the solar connectors, and to correctly make them yourself requires a very expensive tool.

Most boaters we deal with in your situation buy the SMK pre-crimped wire like this, http://www.altestore.com/store/Cables-Wiring/Wiring-For-Solar-Panels/100-SMK-Connector-Cable-10-AWG/p10449/ twice as long as you need to go for your first connection and cut it in 2, one piece for plus and one for minus. For example, if you are using a combiner box, you would use this wire to the combiner box, and then provide your own tinned wire for the rest of the system.The advantage of using professionally crimped connectors vs tinned wire you crimp yourself is worth using a length of non-tinned wire for the outside connection that will be most exposed to the elements.

Unless you have other components that I don't know about that are MC4, I don't see any reason to convert over to MC4, just keep with SMK. Or are you wiring them in parallel with an MC4 coupler like this, http://www.altestore.com/store/Cables-Wiring/Wiring-For-Solar-Panels/MC2MC4-Branch-Coupler-1-Male-to-2-Female-Ends/p7163/? If so, the answer to whether MC4 and SMK are compatible is also a little controversial. Yes they will work together, but some are concerned about long term connectivity, will they eventually not make a solid connection. I've got a foot in both camps for that one. Again, most people just connect them together with no problem. If you are concerned about it, you can use an adapter set like this, http://www.altestore.com/store/Cables-Wiring/Wiring-For-Solar-Panels/SMK-to-MC4-Array-Adapter-Set-MF-Pair/p10616/ .

Sorry, as I said, no short clear answer available. You can give us a call and we can discuss pros and cons with you to help you decide.

Amy
Solar Queen (and boater)
altE Store

Hi Amy,

Thanks for your detailed response which was very helpful for my understanding.

I did find some interesting additional information on the internet, - so it must be true... ;-) but I'm an engineer and it sounds sufficiently credible that you might be interested. (Item in "quotes" below.)

In conclusion, I plan to use available #10 marine grade cable professionally fitted with MC4 plugs at each end, cut than in two as per your suggestion and then connect it to the SMK panels via an altE SMK to MC4 Array Adapter Set. Hopefully the standard SMK leads on the panels will be long enough to allow the serial connection between two panels.

Quote:
"Cross-mating any connector, regardless of the brands involved, is not a UL approved connection. It does not matter that both connectors may have independent UL approvals, as they were tested to their own, specific individual tolerances and specifications.
I have seen numerous connections failing due to cross mating issues. The issue is that the metallurgical chemistry of the contacts are going to be different unless they are from the same manufacturer. Over time, the difference in chemical composition causes oxidation and other issues that can lead to temperature rise and other problems.
Another issue is that, companies don't generally release tolerances for their products. This results in possible gaps in the contacts when cross mating, which leads to arcing, and ultimately connector failure."

I've seen that quote before, which is why I have one foot in that camp. My other foot is in the other camp of being a boater, and making due with what you have available. I think you've come up with a good solution.

BTW, I just wired up the outside horn on our schooner yesterday with heat shrink butt connectors, then wrapped the whole outside wire harness onto the rigging in high quality electrical tape to prevent UV exposure and accidental catching on something while under way. To Tom M's point, we used a dab of dielectric grease in the connector just for good luck.

Amy
Schooner Queen
altE Store