Sae Vs Mc4 Solar Wiring Connectors

I've been doing a lot of research on options for adding external solar power. I realize there is no one right way and many will have different thoughts. That given, if I were buying today (I'm not. My trailer won't be ready until June.) I would buy the Renogy 200 watt suitcase system which includes a 20 amp controller connected to the back of the panels.

But regardless of a specific system, it still comes down to running wire and how long. I've read and heard that MC4s are a real pain, especially to unplug. I've heard them referred to as arthritis unfriendly. Hence, my thought of using SAE connectors instead. I've also read that energy loss is less a function of the connectors and more about distance and gauge of wire.

My thought is to have a short (less than 2ft) wire coming from the controller on the panels as well as coming off the 12V male plug that connects to the trailer. In between I can run different lengths of wire to plug and play in order to try and not run wire any longer than necessary. As long as I keep the SAE connector wires to 10ft, I can run either option with all 10 AWG wire. My thought and hope is to not ever go longer than 25ft-30ft total.

Given all of the above, I'm leaning to going the SAE route. Does anybody have any experience with this that could add some feedback?

Thanks.

 

Hi John,

I cannot speak with any authority regarding your choice of connectors/plugs. I can say, as someone who likes to park in the shade, I am often placing my solar panel at the limit of my wire's reach (20-25'). If I were going to buy another panel I would definitely aim for something lighter and less bulky than what I have (sort of a suit-case, fold-in-half type deal), with ease of use and transport being of value when on vacation.

Cheers,
--Ken

 

Thanks Ken. I have spent forever analyzing the pros and cons of all the choices involved, from panels to controllers to connectors to wire gauge, to how long an extension to run. Often, the benefit of one choice is at the detriment to another part of the equation. Unfortunately I don't think there is ever a perfect answer since it's impossible to know the exact future conditions you will find yourself in.

All that said, I agree with you in that I prefer a folding suitcase setup rather than one larger panel. Size and portability being my preference to lower cost.

 

I had the same concerns about the MC4 connectors but have been using them for 6+ years now without a problem. Yep, they're occasionally a bit finicky to get apart (and my fingers are definitely getting old) but not enough to make me wish I has something different.
I do agree with you regarding the suitcase panel - I wish I had one and will probably upgrade at some point. When we got our 550 the suitcase choices were too expensive for my taste so I bought an inexpensive panel that would fit in our small TV. My advice is to get as much wattage as you can.

 

Thank you for the feedback.

200 watts will provide appx 10.5 amps in best conditions. It probably borders on the largest I'd want. The trailer itself uses a 15 amp fuse on the 12V outlet lines. But I also prefer 200 watts to anything smaller because in any conditions the larger wattage will charge quicker (twice as fast as a 100 watt system). Since it is a portable system I intend to babysit it anytime it is in use and much prefer a small, one time, added cost to have the faster charging panels.

 

I don’t think SAE is rated for outdoor use? Would animal pee, an errant cup of coffee, or a little drizzle when you’re away from camp short the system?

Another connector to look at: Anderson Powerpole PP30 (for 10ga) (link)
Another: Marinco 2-wire (link)

 

Thanks Seth. That’s a good question. I’ll have to check on the outdoor rating. I’ve seen references to the Anderson connectors but don’t know much about them. I would like to keep it simple as far as original setup, and the ongoing trip setups.

 

Just in case you need more to think about - you might consider not purchasing the solar controller with the panel and locating a controller in the trailer. Sounds like you have a trailer on order with a June delivery? You might want to add the CTEK charge controller option. The CTEK also manages charging the battery when connected to the tow vehicle and gives a much better charge than just charging from the vehicle alternator.

I retrofitted my trailer with one and use a SO cord with a Marinco connector on one end to fit the trailer and MC4 connector on the other end to fit the panel. I also have a 100 watt Renogy suitcase panel and have found that I can neatly store the cable in the panel when folded without having to undo the MC4 connectors. I find the suitcase panel to be of very high quality, but it is also a little heavy and bulky. I picked up a cheaper thin flexible panel that I just store under the mattress and it seems to work well if you can get it propped up at the right angle. The same cord works since both panels came with MC4 connectors. At some point I need to try using both panels together to get 200 watts of charging.

 

Thanks Henry.

I've thought waaay too much about all the options. My head starts hurting and I have to stop thinking and start drinking to sooth the pain. ;-)

I've considered a trailer mounted MPPT controller. Would it be better? Yes. Would it be more work and more money? Yes again. Given the current pricing structure, the Renogy 200 watt suitcase with PWM controller is pretty hard to beat. Once I get the wiring figured out I'll give it a go and get some real world results. There's a good chance it will meet my needs as is. If not, I can still add the MPPT controller and just mount it to a board to be placed either in the galley or even propped up on the ground when charging. 200 watts on a good day should charge at 10.5 amps/hr which should be anywhere from 1-3 hours of babysitting the gear. I'd be pretty content with that.

I know there has been some discussion about getting a maximum charge to the trailer battery. Certainly that would be the ideal situation. But I think for the amount of time I would be charging on the road, getting something over 13 volts to the battery in the field will be adequate. Over the course of a year, it will get charged much more at home where I can always get max charging. It will even, likely, get charged plugging in on the road occasionally. Getting less than max charge on a few charges yearly shouldn't really be an issue. At least I don't think it should, should it?

 

I use the MC4 connectors and have no problem disconnecting them. Yes they are a little hard on the hands but they are going to hurt anyway, haha. If you are going to go with MC4, get the original ones by Stäubli. They are probably the best out there. Some of the cheaper ones may not be compatible. Link to Stäubli info below:
https://ec.staubli.com/AcroFiles/Catalogues/PV_Sol-Main-11014092_(en)_hi.pdf#page=16-17

 

Thanks Tom. I'll check them out.

 

Just noticed this rather old thread. For the record, I switched everything over to SAE connectors to avoid the bad connections from "cigarette lighter" type plugs which suck. You need to keep the polarities straight with the SAEs but other than that I find them excellent, simple and have had no problems at all.

 

CI has stopped using the cigarette lighter styles --- I agree with you, they are terrible. They are using a twist lock style in the newer campers.

I'm sure people will have a fit when I say how I solved my wire problem between the panel and the camper. I didn't want to have to carry another spool of wire. I cut off the ends of an heavy duty extension cord --- the female end, I attached that to the twistlock which goes to the camper. I used the female so it is impossible to accidentally plug it into 110.

The male end I attached on the solar panel itself. Theoretically an idiot you could plug the solar panel itself into 120. That would be quite a show. However, since I am the only idiot using this system,I'm willing to accept the risk. I rely on the ground pin (s) to maintain polarity.

This allows me to use the same power cord I use for shore-power between my solar panel and my trailer...25 feet is enough to find a sunny spot at about any camp site. But theoretically I could run much more if I needed

 

John,
I agree that MC4 connectors have very hard-to-release retention gripping.

The SAE connectors are the same design as the flat 4 trailer wiring hitch connectors although they are only 2 connections wide, not 4. The same considerations apply. If they are firmly fitted together, there should be no serious problem with shorting.

Storage of both the actual electrical connections, female and male types, are subject to corrosion and soiling. This will require cleaning before counting on an excellent resistance-free electrical connection.

The other consideration is the gradual loosening up of the pinch action as they are connected and disconnected repeatedly. If moving sites occurs on an almost daily basis, this is something that will require attention to assure optimum efficiency of the charging system.

Cleaning vinegar and degreaser will clean the metal up as one would do before soldering. If the pinch is insufficient, gentle compression on the female receiving component will offer assurance of a good connection. Naturally, if it is possible to keep SAE connectors together as long as possible there will be less wear and tear to reduce pinch and less exposure to corrosive conditions.

Even though MC4 connectors appear to shield the actual electrical contacts when connected, when disconnected, those contacts are just as susceptible as SAE connectors to salt air, etc. so their plus factors are that they hold together well and their negative factors are that most users find them a challenge to take apart. SAE connectors can get snug to seat fully, which is a good thing as opposed to being sloppy and sliding in easily.

Finally, to prevent sea air and rain from corroding the electrical business ends, a compatible "grease" could be applied that wouldn't attack the rubber or plastic body of the connector but would keep the metal protected.

I have never had problems with my SAE connectors, but I have helped fellow campers to set up and crack down and I hate MC4 connectors.

 

Logically, SAE are as suitable as SAE trailer connectors are.

 

I've used the MC4's at least a couple dozen times recently ( and a whole lot in past years connecting/disconnecting portable solar panels, daily)

and

yes they are a pain,
and can easily bind up if not kept clean enough to feel the "click" that holds the connection tight to rubber o-ring inside to make waterproof.

MC4s seem to be used more on heavier gage wire (lower resistance) than SAE so if you have a long run in dusty or morning dew/rain wet area out over a few days, so the advantage is to MC4.

SAE make a lot of sense to me if you keep them clean and put up daily, and my guess is a bit of vinegar will help dissolve salt or scale buildup from being outside.

Tip; separate type connectors but useful related to how not to get gunked up electrical connections pro-tip; (thank you Craig and Cary for diagnosis, finding this issue while refusing to let me leave on a late hectic Friday after factory owner tour...until lights working good...
and Betsy my apologies for the cold roast too!)

My new 7pin trailer connectors from Curt came without weatherproofing and the junior guy at otherwise outstanding foreign auto shop which updates my 4pin to the 7pin harness to my weird german wiring VW neglected to use them...
thats a "duh" on me for not inspecting better.

- only one trip in slushy road salt was enough to degrade the connections, to raise resistance and blow the battery fuse switch repeatedly even tho the CTEK only draws 6a for vehicle charging on CI house battery...

So keep those Cleaned up every so often too...

 

Dielectric grease is your friend! Protects and conditions…

At a local auto parts store, or online:
https://www.amazon.com/CRC-05109-Technician-Electric-Applicator/dp/B000CCIDAA/