MC4 scam buster - what you have all been waiting for

[robbob2112]

Compatability of connectors - lets start with this:
We need both halves of each MC-4 connector to be compatable.
We buy PV panels that come with one half of the connection already present, some of these will plug into another adjacent PV panel ensuring compatability, and some will plug into wiring we are making using PV wire and sourced MC-4 parts.
So to make the wire connections compatable we need to match the manufacturer of the PV panels MC-4's - yet I have no idea if the PV panels use authentic Staubli connection parts or similar parts made by others, or if the PV panels even state such information.
So how do we know the compatability of the connection to the PV panels? Cut them all off the PV panels and use a single source of connector parts, to ensure they must be all compatable?

My PV panels came with a bag attached to each set of connectors. In that bag is the other half of the MC4 connector to match the panel. Won't help if there is an issue and one needs changed, but to start with I am good to go.

Comparing the pins and sockets to the ones from stabuli, temco, and a third brand that wasn't dirt cheap they look pretty much the same. When I have time I will measure them with the digital caliper and micrometer.

I also have some cheap ones that came with the crimper and they look OK, but not as heavy or well made. These should make for a good test set.


Since I have the different sets I intend to use the YR1035 meter to see if there are obvious differences connecting to their mates and the other types.


This is simple data gathering because enquiring minds want to know, not to suggest interconnecting the different brands.

 

[Hedges]

You're talking about measuring dimensions, and resistance.
But wait! There is more!

Contacts have to be compliant. when mated, they undergo deformation. Elastic? or Plastic?

I've used pin sockets that had a spec for range of pin diameters they could mate to, which was greater than their spec for recovery from deformation. Once mated with a large pin, they should be able to repeatedly mate to such size pins but not to smaller pins they could be used with when fresh.

 

[Boron]

Why not just use the internals from good quality terminal blocks then?

Oh you mean those horrible choc blocs. These are sold for 60A duty 10AWG. You must know how bad those screw threads are. In fact most consumer units sold in popular DIY UK stores have weak sloppy brass screws which are prone to stripping threads.

Have you noticed there isnt a double screw clamp version made ie two screws clamping the wire core. So that pic would be twice as long with 8 screws in total.

I saw a vid of a guys RV truck motoring down the highway, on fire coming out of his battery shelf. The inverter he used had Cheap Charlie connections like this and the truck vibrations loosed the screws while it was charging.

Yes, insurance issues, tick boxers not tested (its work in hand if I had had my Lion fire that still has me shell shocked)

Its probably cos I majored in both Electrical and Mechanical Eng that I have this critical view since venturing into the world of high current. BTW if you study the way pre/post war dc high current systems were put together you will see that there is a strong influence of sound mechanical design. I find this approach largely missing or trivialised.

 

[robbob2112]

You're talking about measuring dimensions, and resistance.
But wait! There is more!

Contacts have to be compliant. when mated, they undergo deformation. Elastic? or Plastic?

I've used pin sockets that had a spec for range of pin diameters they could mate to, which was greater than their spec for recovery from deformation. Once mated with a large pin, they should be able to repeatedly mate to such size pins but not to smaller pins they could be used with when fresh.

Not going to dig my hole that deep. All of my MC4 are for 10awg wire. I could repeatedly plug and unplug to see if there is a change in resistance across the connection. How often does a MC4 get cycled? I would guess most not more than a few times in their lives. So, maybe 10 times per pairing.

I don't have a ton to waste so different permutations will wait until I win the lotto.


If I were @Will Prowse I would make up test cables with as many MC4 varieties as he can find then plug them in different combinations in a fire safe area. Then run a constant 10 to 15 amps through them and see what happens.


Might give him something to do with all of his spare power from all those batteries.

 

[Boron]

You see @robbob2112 , what you do in the privacy of your own shed is your business. In the commercial world you have to take your views and practices out to your customer and charge $$$$$. Homebrew opinions are cheap but you cant sell them unless you can back up the product. The alternative can be a very expensive mistake. How ever when you sell and install a system you rely on what it says on the component box and does Cheap Charlie care about his brand reputation? Does your installer carry a paper audit trail to show the provenance of system components? (aerospace practice). I have exposed fake solar cable with 4mm2 marked as 6mm2

I proposed in my OP not as a recommended practice but as a discussion point given the poor reliability and IMHO flawed design of the ubiquitous MC4. I focussed on back to basics, solid well proven concepts. The design needs more work, I would like M4 screws doubled up (making 4 per coupling and would more work on crimping and sleeving. My result would be rock solid not reliant on fine tolerances and still cost less than an MC4. I contend you would never get arc problems and fires. But there's huge Big Corp profits at stake

 

[Hedges]

Wire gauge wouldn't be the issue.

We may get PV panels that were mated to each other, then disconnected.
We could mate to RSD or an extension wire. If new connector has smaller male pin, it may have insufficient contact force on stretched female socket.

 

[cs1234]

We could mate to RSD or an extension wire.

Dang! You're right.

With RSD requirements and Microinverters being so prevalent, what brand of MC4 connectors are on the common brands of those? The MC4 connectors all have to work perfectly with Enphase Microinverters, SolarEdge Optimizers, Tigo RSD devices, etc..

 

[Bananaman321]

My PV panels came with a bag attached to each set of connectors. In that bag is the other half of the MC4 connector to match the panel. Won't help if there is an issue and one needs changed, but to start with I am good to go.

Comparing the pins and sockets to the ones from stabuli, temco, and a third brand that wasn't dirt cheap they look pretty much the same. When I have time I will measure them with the digital caliper and micrometer.

I also have some cheap ones that came with the crimper and they look OK, but not as heavy or well made. These should make for a good test set.


Since I have the different sets I intend to use the YR1035 meter to see if there are obvious differences connecting to their mates and the other types.


This is simple data gathering because enquiring minds want to know, not to suggest interconnecting the different brands.

I never realized this was such an issue I always chalked it up to contaminated connections and user error.

I guess I'll have to double down on reading that negative feedback before I add to cart on my next Amazon order.

I'm still an avid supporter of proprietary connectors with all black wire unbounded goof up polarity somewhere.

 

[Will Prowse]

Not going to dig my hole that deep. All of my MC4 are for 10awg wire. I could repeatedly plug and unplug to see if there is a change in resistance across the connection. How often does a MC4 get cycled? I would guess most not more than a few times in their lives. So, maybe 10 times per pairing.

I don't have a ton to waste so different permutations will wait until I win the lotto.


If I were @Will Prowse I would make up test cables with as many MC4 varieties as he can find then plug them in different combinations in a fire safe area. Then run a constant 10 to 15 amps through them and see what happens.


Might give him something to do with all of his spare power from all those batteries.

I have wanted to do this for a while but there are quite literally hundreds of them.

My current recommendation is that you have to use identical MC4s together only. And then when you connect an array to an MPPT, butt splice connectors and marine grade heat shrink. That way there is no chance of issues at all. This does require cutting off the MC4 at the end of the string. But I've been doing this and I have had no melted MC4s. I have melted many MC4s

 

[Will Prowse]

Hi Guys - this is not a clickbait rubbish. Its my genuine attempt to overcome the serious MC4 problem - a demountable connection system that doesnt burn out on you.

So here is my Mk1 version
Solid brass mechanical straight coupling using 2 pairs of hex grub screws. The cable is standard 6mm2 solar TUV (10AWG). I hope the poor quality pix are self explanatory.
You could use a rubber tube (UV res) as a simple cover and squirt some Si grease in to keep water out. Or you can use a heatshrink sleeve if you dont expect to have to demount it (by stripping the sleeve - less convenient maybe.
Rated for 50A as per cable. Cost <$1. No crimping tool needed as the grub screw points and copper sleeve grip the strands tightly.

What do you think? Armchairs - do your worst

BTW I have no commercial interest - the design is offered as GNU for the benefit of Solar Members and saving on roof fires.

I think a thick walled butt splice connector is better. A true termination, which is a mechanical gas-free joint, is better than screws.

 

[robbob2112]

You see @robbob2112 , what you do in the privacy of your own shed is your business. In the commercial world you have to take your views and practices out to your customer and charge $$$$$. Homebrew opinions are cheap but you cant sell them unless you can back up the product. The alternative can be a very expensive mistake. How ever when you sell and install a system you rely on what it says on the component box and does Cheap Charlie care about his brand reputation? Does your installer carry a paper audit trail to show the provenance of system components? (aerospace practice). I have exposed fake solar cable with 4mm2 marked as 6mm2

I proposed in my OP not as a recommended practice but as a discussion point given the poor reliability and IMHO flawed design of the ubiquitous MC4. I focussed on back to basics, solid well proven concepts. The design needs more work, I would like M4 screws doubled up (making 4 per coupling and would more work on crimping and sleeving. My result would be rock solid not reliant on fine tolerances and still cost less than an MC4. I contend you would never get arc problems and fires. But there's huge Big Corp profits at stake

Not arguing with you that there is a better way.

Having worked on military aircraft I've seen many of them. The ubiquitous Cannon plugs on nearly all the gear I touched. Solid copper pins, rubber plugs, EMI shielded with waterproof backshells providing strain relief.

Not wanting to spend $600 per connection or needing that sort of setup I will evaluate what is available and just use quality.

My install is my own and doesn't matter to anyone but me.

I think for your design needs a lot of work to be viable. A pointy or flat bottomed screw either one will damage the wires. With your barrel you need to push the wire smoothly from both sides without damage.

The split-bolt @Hedges posted is an example. The thing you mentioned as a busbar if flattened. The larger version all have a lower plate that raises smoothly to push the wires together. Then you wrap them in friction tape.

Not ideal for smaller wires or fine stranded wire though.

 

[robbob2112]

I have wanted to do this for a while but there are quite literally hundreds of them.

My current recommendation is that you have to use identical MC4s together only. And then when you connect an array to an MPPT, butt splice connectors and marine grade heat shrink. That way there is no chance of issues at all. This does require cutting off the MC4 at the end of the string. But I've been doing this and I have had no melted MC4s. I have melted many MC4s

Pick 10 common types and do it up. The most common 3 and then random stuff.

 

[seneysolar]

To simplify things. Before mixing brands i take a bare pin and socket and slide it in the panels respective factory installed mc4. If its not a tight/snug fit its no good. There should be some decent tension sliding the pins in.

Now, i dont buy the cheap crap on Amazon but i have found most MC4 interchange just fine. Its impossible to stick with 1 brand, theres too many panel manufacturers using whatever.
***The installer (you) needs to determine compatibility at each connection***

If you buy cheap crap and use it blindly, please post pictures in the "up in smoke" section. We all love pictures of melted stuff

 

[Bananaman321]

Pick 10 common types and do it up. The most common 3 and then random stuff.

I think the real test is mixing the brands because it's impossible not to. A lot of the IMO's and some of the inverters have the connectors on the device some roles of pv wire come with connectors installed. It is a lot to ask of people purchasing new products and cutting the connector off because it is a different brand.

Next it will be an electrical outlet conspiracy and some knucklehead will want me to brand match household plugs or garden hose connectors.

Absolutely NOT that's why they are built to a standard if you can prove that a part does not meet the standard than that's the information I'm interested in I don't care if it is made in US, UK, India, China or BFE.

If your going to test connectors you need to test compatibility as well,they should be tested in resistance, tested to failure in amps and tested up to "1" bar in pressure.

Edit: Bottom line is MC4 is not a brand it is a standard that must be met.

Sorry @robbob2112 I got a little carried away don't take to .

 

[Will Prowse]

You can also test the resistance between dissimilar MC4s. Or you can measure the depth of plug to ensure they have good contact. Or use a heat camera.

 

[robbob2112]

You can also test the resistance between dissimilar MC4s. Or you can measure the depth of plug to ensure they have good contact. Or use a heat camera.

I was planning thermal camera

 

[Boron]

I think the real test is mixing the brands because it's impossible not to. A lot of the IMO's and some of the inverters have the connectors on the device some roles of pv wire come with connectors installed. It is a lot to ask of people purchasing new products and cutting the connector off because it is a different brand.

Next it will be an electrical outlet conspiracy and some knucklehead will want me to brand match household plugs or garden hose connectors.

Absolutely NOT that's why they are built to a standard if you can prove that a part does not meet the standard than that's the information I'm interested in I don't care if it is made in US, UK, India, China or BFE.

If your going to test connectors you need to test compatibility as well,they should be tested in resistance, tested to failure in amps and tested up to "1" bar in pressure.

Edit: Bottom line is MC4 is not a brand it is a standard that must be met.

Sorry @robbob2112 I got a little carried away don't take to .

Do some homework https://en.wikipedia.org/wiki/MC4_connector
MC4 is an original Staubli design not a standard. there are 100's of copies and styles flooding the market
Product certifications and the manufacturer's warranty only apply if MC4 connectors are mated to connectors from the same type made by Staubli Electrical Connectors and the instructions in the manual were followed
The MC4 connector is UL rated at 1500 V DC and up to 95 A with the 6AWG PV Cable. MC4-Evo 2 has both UL and IEC certification ratings of 1500 V DC and up to 70 A with 10mm² PV Cable, depending on the conductor size used in pairs.

There's a lot can go wrong with the flawed design (MC3 (3mm pin) started out 1996 rated 30A. MC4 (4mm pin) came out in 2004

 

[Boron]

I think a thick walled butt splice connector is better. A true termination, which is a mechanical gas-free joint, is better than screws.

Agreed 100% plus a proper hydraulic tool and anvil to get a professional crimp (cant do that with mickey mouse pliers)

 

[HRTKD]

For those in the RV community that deploy PV panels on the ground, the MC4 connector is a good way to go. I've had good luck with most of the MC4 connectors on my ground deployed panels, but there's one connector that is booger to disconnect every time. It requires the release tool no matter what. All the rest of them can be done without the tool.

They've been connected/disconnected probably 100 times.

 

[OffGridForGood]

Some items mentioned come with "MC-4 style" connectors - PV panels, Tigo, Splitters, combiner boxes, even some small AIO have built in connections in this type.

Q. How would the average consumer know 'which' type/Mfr the connector is to be able to match it with the apporpriate other half?
@robbob2112 mentioned his unit came with the mating other half of the connector in a bag, but this doesn't seem to be a common thing.

 

[cs1234]

If the MC4 connector isn't an open standard with a certifying / testing group of some sort verifying compatibility between brands, it shouldn't be used industry wide. Having to make sure to mate only like brand connectors is an accident waiting to happen for something consumers are now using themselves on numerous products.

Spoiler: Unacceptable, shame on NEC

 

[HRTKD]

Q. How would the average consumer know 'which' type/Mfr the connector is to be able to match it with the apporpriate other half?

The solar panels I plan to purchase has it explicitly stated in their brochure that the MC4 connectors that they use are Staubli and includes the part Staubli numbers too. It doesn't get any better than that.

 

[Bananaman321]

The solar panels I plan to purchase has it explicitly stated in their brochure that the MC4 connectors that they use are Staubli and includes the part Staubli numbers too. It doesn't get any better than that.

This is my point exactly. I've spent the last hour downloading documents from manufacturers with MC4 connectors on their equipment and not one of which specifying the brand of MC4 connector they are using some just say solar connector.
And not total knockoff manufacturers but and not limited to rebranders such as EG4 Rich solar Aims

At least Victoron sells supposedly compatible connectors they say Victron on them but I'd really doubt they actually manufacture them.

And then there are devices like these and in phase which are designed to connect directly with the solar panels and I can almost guarantee you they're not the the same brand at least 75% of the time.

So at this point I give up as long as the connectors are clean and solid and they connect together then so be it if they burn up I'll replace them at that point.

There was something to take away from this whole experience I lost it in confusion good luck figuring this out.

 

[ThaiTaffy]

This is my point exactly. I've spent the last hour downloading documents from manufacturers with MC4 connectors on their equipment and not one of which specifying the brand of MC4 connector they are using some just say solar connector.
And not total knockoff manufacturers but and not limited to rebranders such as EG4 Rich solar Aims

View attachment 231311At least Victoron sells supposedly compatible connectors they say Victron on them but I'd really doubt they actually manufacture them.

View attachment 231310And then there are devices like these and in phase which are designed to connect directly with the solar panels and I can almost guarantee you they're not the the same brand at least 75% of the time.

So at this point I give up as long as the connectors are clean and solid and they connect together then so be it if they burn up I'll replace them at that point.

There was something to take away from this whole experience I lost it in confusion good luck figuring this out.

That's why your not supposed to mix them mc4 is just a term we use to describe the connector for ease in reality each manufacturer has its own name if they don't, they break Stabuli's trademark.
It's a crapshoot brought on by stabuli really, that's why boron is so adamant on calling all other brands copies though they never seemed to have gotten a patent. Personally I would say use whatever brand is best available as long as it has a UL listing I won't touch stabuli products here as the market is flooded with identical copies also I'm not a fan of the swiss even if they pretend to be a German company

 

[Bananaman321]

That's why your not supposed to mix them mc4 is just a term we use to describe the connector for ease in reality each manufacturer has its own name if they don't, they break Stabuli's trademark.
It's a crapshoot brought on by stabuli really, that's why boron is so adamant on calling all other brands copies though they never seemed to have gotten a patent. Personally I would say use whatever brand is best available as long as it has a UL listing I won't touch stabuli products here as the market is flooded with identical copies also I'm not a fan of the swiss even if they pretend to be a German company

I don't even know how I'm supposed to know if the ones attached to my equipment are UL listed let alone the knockoffs I purchased ha ha ha