MC4 connectors a massive scandal

[Mattb4]

The old saying KISS If it aint there it cant go wrong.

In short, dont use MC4s on panels. Use solid crimp butt splice cable connections. Think of it - panels are supposed to be in place for decades? If you have to replace one its a significant effort, so cutting and replacing a cable splice (done with proper tools of course) is surely a no brainer. Stick to <48Vdc its inherently safe but uses more cable - safety vs bean counters.

...

In my use I frequently rearrange and adapt my panels setups so having a plug in means of working with them is very handy. From a safety perspective the MC4's are better than forcing people to work around a possible hot wire(s) from sun exposed panel(s). A better plug and socket that used a twist lock method rather than the locking tabs would be good.

 

[Boron]

In my use I frequently rearrange and adapt my panels setups so having a plug in means of working with them is very handy. From a safety perspective the MC4's are better than forcing people to work around a possible hot wire(s) from sun exposed panel(s). A better plug and socket that used a twist lock method rather than the locking tabs would be good.

An Anderson plug and socket if you must - favoured by RV crowd? IMHO dont touch the XT160 type favoured by RC kids for Lipo packs, scooter, drones etc.

Below rated for 175A - I believe there is a version called "spark free" which has a guard ring to catch the disconnect spark but IMHO live disconnect not recommended except in emergency. There are some handles you can attach to the holes to assist manual disconnect effort. Cant do that with an MC4 - use cable cutters.

 

[Mattb4]

An Anderson plug and socket if you must - favoured by RV crowd? IMHO dont touch the XT160 type favoured by RC kids for Lipo packs, scooter, drones etc.

Below rated for 175A - I believe there is a version called "spark free" which has a guard ring to catch the disconnect spark but IMHO live disconnect not recommended except in emergency. There are some handles you can attach to the holes to assist manual disconnect effort. Cant do that with an MC4 - use cable cutters.

Combining both Pos and Neg into one plug would make it difficult to wire panels in series and parallel. However for the run cables to SCC I have often thought that a combined 2 wire (with ground) solar rated feeder wire would be good.

I have not seen the type of connectors that RC devices use.

 

[robbob2112]

Anderson connectors are not water tight. They make caps and boots so you can wrap up the kiddies, but in weather water would get in and corroded things.

The RC device connectors are the XT30, XT60, XT90, or just the low amp powerpole connectors. They use them on the pack from the rent-a-scooter things. Yellow with a point to one side.

Connection for wires is a round solder cup on the real ones. There are soooo many fake it would be difficult to make sure they were all real.

Fake ones have the same connection problem as real and fake MC4 connectors.

Same problem, none are intended for wet rain and would either corroded or short out on panels. So you would have to wrap every connector in rubber tape.

Dispite the issues either a permenant connection or MC4 is the best for the job in solar.

 

[ksmithaz1]

Had my first failure of a MC4 connector and it was a pain to find. Mostly because symptoms were odd in that most of the time the array produced. But ever now and than it seem to be erratic . I was not sure if the PowMr AIO was to blame . But the last few days I was getting a beep alarm during the day followed by another beep a few seconds later and noticed on the screen that production was zero for a few seconds. By spending a lot of time watching things I noticed the icon for solar connection disappearing on the first beep and reappearing on the second. Thus an intermittent connection. Dang it time to check everything out.

So I went through tightening screws at breakers and disconnecting MC4's one by one an trying to see if anything was obvious. On one of the panels MC4 I noticed there was moisture inside the body of the MC4. it was hard to see if this was the issue but out of caution I cut it off and replaced it with a new Staubli brand one. Pulling it apart showed all kinds of corrosion and a badly done factory crimp jump. (This cable was bought way back in my solar journey before I started making my own cables.) Hope this fixes my issue but it does encourage me to replace more of the old MC4's.

I have 6 strings, two are used panels, 8 x CS250's. One of the strings had erratic output, you could see on the graphs 5 lines with the same dips and curves, and one that just dropped out every so often or went low. I pulled one panel at a time until I found it. Set it to one side. Diodes checked out OK. Bought a small MPPT, tested for a day, same problem. Replaced the MC4's problem went away. No visible signs of a problem, panel is back in the string, all 6 outputs float in sync. Have I mentioned MC4 is junk, from the contacts to the housing?

 

[kolek]

You're grabbing one conductor in the middle of a series string that has 400V to 600V between the ends.
You rely on no other point being grounded at the same time.

Nope. The series string is interrupted in 2 places. The terminals that I'm working on, and another separate place. There's no potential between the connectors I'm working on because the solar array has another disconnected MC4 connector which I open prior to doing the work.

 

[kolek]

I have had 100's of MC4 connector failures on my Commercial site.

David I really appreciate this information. I feel vindicated for switching out the the main MC4 connectors on my array. What bugs me about MC4 connectors is there is no "clamping" or even solder between the two terminals, it's just 1 tube slid into another. It's not "oxygen free" like a good crimp. Over time, I would expect to see oxidation forming on the surfaces of the connectors, gradually worsing the connection over time. I get that it's more convenient than regular bolted ring terminals when you want to disconnect, but how often are you disconnecting your solar array? And is the added convenience of MC4 worth a fire hazard? Just my 2 cents.

 

[kolek]

Have I mentioned MC4 is junk, from the contacts to the housing?

Wholeheartedly agree with this point. At least the junk MC4 connectors I'm seeing, no way those things are going to last 25 years.

 

[ShirBlackspots]

The old saying KISS If it aint there it cant go wrong.

In short, dont use MC4s on panels. Use solid crimp butt splice cable connections. Think of it - panels are supposed to be in place for decades? If you have to replace one its a significant effort, so cutting and replacing a cable splice (done with proper tools of course) is surely a no brainer. Stick to <48Vdc its inherently safe but uses more cable - safety vs bean counters.

I cant comment on High voltage systems, 400 - 1000V dc systems there must be NEC regs for cable splices - the whole concept scares the hell out of me and I would not go anywhere near such an installation - but Im old school. I far rather see multiple marshalling hubs with field inverters making an ac micro grid. We know how to handle outdoor ac power.

Higher voltages are better because of lower amps. 12V systems put out massive amounts of amperage.

a 5000W load on 48V is 104.167A, vs 416.667A on 12V

 

[ksmithaz1]

"We" have been making watertight high current contacts for years. Unfortunately they tend to be $30 each. The MC4 design was engineered for the contacts to be as inexpensive as possible, and the housing was an afterthought. I don't give a crap about who makes it, the design is bad. I've been considering alternatives since I installed my gear.

 

[kolek]

416.667A on 12V

Plus the fact that 666 appears in that number makes it even more scary than the 416.667 amps.

 

[Boron]

Anderson connectors are not water tight. They make caps and boots so you can wrap up the kiddies, but in weather water would get in and corroded things.

Good stuff - Im in favour of drilling some 1mm holes in the Anderson plastic bodies to access the connection area (and another in the wire part for good measure - may not be needed?). The idea is that when you have made your connection, get a simple grease gun charged with Si grease and pump it down the hole, like you are charging a bearing - see it squirt out the ends - an oily rag method. That should keep the water out indefinitely IMHO - assuming you are not going to be meddling with it much if at all. If it has to be pulled apart often for maintenance etc then - back to the drawing board - maybe a crude bolting together of ring terminals and sealed up with heat shrink - IDK?

What do you think guys

 

[Boron]

Higher voltages are better because of lower amps. 12V systems put out massive amounts of amperage.

a 5000W load on 48V is 104.167A, vs 416.667A on 12V

Hmm no sh8t Sherlock! I believe in 24V systems (lots of generic auto gear around to support his level). Just use std Solar cable 10AWG good for 60A + and it can run up to 90C (keep the kids away). Use 2 strings instead of one for 100 Amax. Its not rocket science, just costs a bit more cable. Design your runs to be maintainable if needed. I would use a proper field but splice with a loop of extra cable in the rare event a disconnect is needed (cut out and new splice). Not an MC4 in sight. Maybe a grease packed Anderson, local IP 65 junction boxes. Use cable bootlace crimps to feed full sized brass terminal blocks. Old school stuff.

 

[JRH]

Anderson connectors are not water tight. They make caps and boots so you can wrap up the kiddies, but in weather water would get in and corroded things.

I am not disagreeing with your overall concepts , but the Andersons are a pretty good quick connect if installed properly ..the rest of your examples I have no opinion on… but 8m sure they have their place in the world

I have used andersons for decades , for many reasons ,many times from boats to snow plows to my solar wire runs from the panels to the equipment location I am using them on and the 4 new arrays new ones I am building now…

There are se real kinds but I’m speaking of the standard Anderson ,stout , 2 pole push in connector about 2” wide and long…I get them from PowerWx …

They make a great stable connection and easy quick connect ….

They were NEVER meant to be water proof ( but reasonably water resistant if installed correctly) ..

If they are just hooked up and dangling in the rain or wheel splatter of a salt truck or boat trailer , sure they will get messed up… incorrect installs is a giant cause of many good components in life..maybe the biggest problem there is in DIY …

I have rubber caps and boots for mine of two designs but only use the end cover types for electric safty..not so much for water protection as the connections are always terminated and live in a waterproof junction box ..with a gasketed door ..it never has any water inside …other than ambient humidity.

They alway should be installed in a decently protected environment . If done that way it will probably exceed it “disconnect cycle life” before it ever fails due to water or anything else.

The ones on my last snow plow lasted the full 10 years of service on my truck ( then I sold it) I used no special install tricks except make the mating connection inside the truck engine compartment up high…
protected from the water and salt crap…

I have never seen a properly made up and maintained one corrode ( if the lugs were crimped properly , and heat shrinked properly …and mounted in a safe place

As far as corrosion the contacts that mate to connect are self cleaning with a special textured silver finish over the copper connectors when connected or disconnected ..there is alway a fresh new clean surface area path if you look down inside the fitting after a few uses.

Someone has to doing something wrong to have corroded or flooded out Anderson in a reasonably typical environment…. If you didn’t want to have a quick connect or disconnect feature it would be silly to even use them…

Any one considering them should always remember ( unless somthing has recently changed)
the SB 175/series are the only anderson connector that can “reduce or step up” the wire size between 6ga and 1/0 awg on the same fitting.

Thst is a huge help when joining two size wires for different needs or long runs…

( for example ) you order the 175 6ga side and it will mate properly with the 175 2ga side or 1/0 or 4 ga or whatever side . Each side has different ferrels but will still mate together ..

.I use a 6 ga set up from my combiner box that steps up to a long 1/0 pv run ,( yes ,far to large) then steps down to 2 ga to hook up the wire to the Victron 150/100 on that particular array.

The outvsides are identical but the insides are made for locking in different internal ferrels ..the regular ones only accommodate one size wire for both sides of the connection..

There are no perfect connection I have found , just different ones for different purposes…

I don’t have any but it seems they make a 3 pole version for people wanting 3 wires on each run…

I love mine…they will certainly out live me and my gear…

J.

 

[JRH]

Good stuff - Im in favour of drilling some 1mm holes in the Anderson plastic bodies to access the connection area (and another in the wire part for good measure - may not be needed?). The idea is that when you have made your connection, get a simple grease gun charged with Si grease and pump it down the hole, like you are charging a bearing - see it squirt out the ends - an oily rag method. That should keep the water out indefinitely IMHO - assuming you are not going to be meddling with it much if at all. If it has to be pulled apart often for maintenance etc then - back to the drawing board - maybe a crude bolting together of ring terminals and sealed up with heat shrink - IDK?

What do you think guys

It isnt nessacery if properly mounted and the grease would certainly hinder gripping that rascal to be separated if you wernt careful… I spray mine now and then inside and carefully with a little WD but I don’t need to…they’ve just work… the6 never seem to quit…
I’m just abit OCD about maintence stuff… ..

J.

 

[robbob2112]

I have some SB175 connectors with a backside water boot and it is mounted under my front bumper with a rubber plug. It stays water tight. Has been there for a good number of years and never has more than a drop of water inside it. The mating side has some 1/0 heavy duty jumper cables that are 20' long. Bought it around 20 years ago. I mainly used it to jump start other vehicles, but on the rare occasion I could just plug it in and jump the truck without ever raising the hood.

This was back in the bad old days before the NOCO jump starters were common. It looks like the day I put it on except faded some. I bought it as a kit to just install and it was expensive at the time and more so now.

Now - I wouldn't use the SB50 or the powerpole connectors for solar without wrapping in rubber tape because they are constant use and have no means to keep the water out while connected.

I have seen some knock-off "upgrades" recently that also had rubber o-rings for the wires and seals on the connectors. They cost as much as an Anderson and look to be built as well. Those I would consider trusting with solar wires, but seems a waste at only 20amps or less. If the claims are real they are every bit as good as anderson and are rated for direct water spray from all sides. Wish I could find a link.

I just looked and there is a thin coating of grease on the pins that mate and the only place that is missing is where the pins slide on each other.



On a side note - the truck battery has been giving me problems with not holding a charge - group 24 standard FLA battery. So I checked it and added 8 cups of RODI water (I know, it isn't distilled, but it is the next thing to it, zero PPM and de-ionized) to the cells, at least two were all but dry. Teach me to think "maintenance free" means I can ignore it. It isn't but about 4 years old so I wonder if it is ruined or not.



I have only done a few of the original style MC4 connectors at this point and they and less than 3 months old so I can't speak to the longevity of them. They seem like they should hold up pretty well.

So - I noted 3 styles above - are all three compatible with each other or will they not even mate the shells?

 

[JRH]

I have some SB175 connectors with a backside water boot and it is mounted under my front bumper with a rubber plug. It stays water tight. Has been there for a good number of years and never has more than a drop of water inside it. The mating side has some 1/0 heavy duty jumper cables that are 20' long. Bought it around 20 years ago. I mainly used it to jump start other vehicles, but on the rare occasion I could just plug it in and jump the truck without ever raising the hood.

This was back in the bad old days before the NOCO jump starters were common. It looks like the day I put it on except faded some. I bought it as a kit to just install and it was expensive at the time and more so now.

Now - I wouldn't use the SB50 or the powerpole connectors for solar without wrapping in rubber tape because they are constant use and have no means to keep the water out while connected.

I have seen some knock-off "upgrades" recently that also had rubber o-rings for the wires and seals on the connectors. They cost as much as an Anderson and look to be built as well. Those I would consider trusting with solar wires, but seems a waste at only 20amps or less. If the claims are real they are every bit as good as anderson and are rated for direct water spray from all sides. Wish I could find a link.

I just looked and there is a thin coating of grease on the pins that mate and the only place that is missing is where the pins slide on each other.



On a side note - the truck battery has been giving me problems with not holding a charge - group 24 standard FLA battery. So I checked it and added 8 cups of RODI water (I know, it isn't distilled, but it is the next thing to it, zero PPM and de-ionized) to the cells, at least two were all but dry. Teach me to think "maintenance free" means I can ignore it. It isn't but about 4 years old so I wonder if it is ruined or not.



I have only done a few of the original style MC4 connectors at this point and they and less than 3 months old so I can't speak to the longevity of them. They seem like they should hold up pretty well.

So - I noted 3 styles above - are all three compatible with each other or will they not even mate the shells?

Yep…long time ago …I rigged my connects on my 250 inside the engine compartment by knocking one of the vertical plastic grill bars on the front and the the connecter from the plow would slide thru and mate the other side over behind the trucks fuse box… unless I ran off in a river , it stayed very dry.
I did somthing simalar to the grave/ salt spreader I kept on the back…during the winter…

Btw, I never made a dime pushing snow or salting roads , if you subtract the price of the truck that I totally destroyed over a 10 year period with rust and front end damage…

I hear you can , but I sure didn’t …

But those Andersons …them little guys were still ready to roll as the wrecker towed my truck away to scrap…

 

[Suijkerbuijk]

Personal i think about the mc4 is what for volt and ampère you use.
For people that only use 22volt to 40 volt panels on a 12/24 volt battery systeem.
This will do the job just fine so long your ampère are low .
So for a normal user case on a boat , car or small RV .
It will be fine.

 

[Mattb4]

What MC4's need is a way to indicate if they are going wonky or bad. Just looking at the durn things, or even feeling for heat, there is not much sign of the evil lurking inside. Fair face hiding foul heart. Maybe some kind of color change should happen as they degrade?

Glossy black-100%
Dull black-80%
Grey-50%
Dull White-0%

Glowing red-Considered a bad sign.

 

[JRH]

What MC4's need is a way to indicate if they are going wonky or bad. Just looking at the durn things, or even feeling for heat, there is not much sign of the evil lurking inside. Fair face hiding foul heart. Maybe some kind of color change should happen as they degrade?

Glossy black-100%
Dull black-80%
Grey-50%
Dull White-0%

Glowing red-Considered a bad sign.

Well shucks…good news ... I’ve already had the kind that warn ya “before” they fail.. they crumble into little pieces in your hand as you try to insert them together…

In all fairness ,I think these staublis that came on the new panels are made much better than what I got 2 years ago and would work well if I could find all Staubli parts to finish out my needs… .. but it’s not easy… and everywhere you call has a different song and dance about the mc4 stuff they sell …” but it’s just as good as Staublie” and cost less….

It appears I have to mix in some other genaric stuff… …So I’m Gona clip em off and save them for another use …

I will do it from scratch like I did the other array…easy , fast , safe and it has worked great…

J.

 

[kolek]

Someone make a case against plain ol' ring terminals. Aside from the fact that you have to cut off the heat shrink if you ever disconnect.

 

[cs1234]

Someone make a case against plain ol' ring terminals. Aside from the fact that you have to cut off the heat shrink if you ever disconnect.

If you're up on a roof, attempting to connect two ring terminals together with a bolt and nut, you are much more likely to drop them, have them roll down the roof, and curse your very existence. If on the ground, you will have to search through the grass. Either way, potentially not fun.

 

[Suijkerbuijk]

Decoding the Variety: Exploring Different Types of Solar Panel Connectors - Renhotec Pro

Solar panel connectors are vital components of any solar array. They enable quick installation, replacement, and maintenance of PV panels.

renhotecpro.com

Type of solar Connector and the power it can handel

 

[kolek]

you're up on a roof, attempting to connect two ring terminals together with a bolt and nut, you are much more likely to drop them, have them roll down the roof, and curse your very existence. If on the ground, you will have to search through the grass. Either way, potentially not fun.

@cs1234 my arch nemesis shows up to wreak my day. lol

Look pal, the problem is you're a cat wearing a necktie. Cat paws aren't shaped right for carrying nuts and bolts, that's why you're droppping them. And anyway, so you might drop a couple. Big deal. Buy and carry a few extra.

@DavidAmon is seeing MC4s in a commercial install starting fires. Which is worse? Dropping a couple nuts or starting a fire?

 

[Suijkerbuijk]

@cs1234 my arch nemesis shows up to wreak my day. lol

Look pal, the problem is you're a cat wearing a necktie. Cat paws aren't shaped right for carrying nuts and bolts, that's why you're droppping them. And anyway, so you might drop a couple. Big deal. Buy and carry a few extra.

@DavidAmon is seeing MC4s in a commercial install starting fires. Which is worse? Dropping a couple nuts or starting a fire?

Maintaining the systeem .
Than you do not have fire.

For the rest mc4 you have to set the under the panel not in the full sun light.
Not under the glas it self but under the frame..
Than solar panel need space from the roof and set it so close than even water can not run under them .

Mc4 connection have iso so it have to handel it.
Pay for real stuf and not cheap junk


Attach files you see brand and connector types.
That are test on the EU .