What are the differences in a T4 connector and a MC4?

[howardwheeler]

I've never hooked up solar panels before and now face two different connectors: T4 and MC4. Is one better than the other or more suitable for particular applications? And most important, do they plug into one another, in other words, can you have a mixed system where, for example, a T4 connector on a panel must mate to a MC4 connection on an extension cable?

[howardwheeler]

I had to parallel because the open circuit voltage on my panels was around 47 volts, and it is possible for me to be in near zero weather, which made the cold compensated voltage around 51.3 volts per panel. Total would exceed the 150 volt rating of my Morningstar MPPT controller. They said that could fry the controller. So I paralleled three sets of 8 gauge wires to my controller. I think my panels are considered 36 volt panels, not 24 volt. Thanks.

[mike-s]

Almot wrote:
I recall, they are installing 3*315W in parallel. So - yeah, about tens of amps 🙂

Words like "and" mean things. MC4s are only rated for 20A, and a 315W panel (24V) is going to put out about 10A, so he wouldn't parallel 3 such panels through one connector, he'd have 3 runs to the controller. But with 24 volt panels, he'd need to be running an MPPT controller to get 12 V out. So why would he parallel the panels in the first place? It would make more sense to run them in series, and have ~100V @ ~ 10A into the controller.

Almot wrote:
Yes, Amphenol headquarters are in the US. TUV protocol (of their H4 testing) is by Germans.

Uh, what? TUV is the German equivalent of Underwriter's Labs (UL). It's not a protocol, and it's not affiliated with Amphenol in any way, other than that Amphenol may use their services, just as the Swiss Staubli might use UL services for products they want to sell in the US.

Almot wrote:
As said, no tools are required for disconnecting MC4 and its clones.

A tool most certainly is required for disconnecting them. Since 2008, the NEC requires it, so that's how all the current connector manufacturers make them.

Your responses show a lack of understanding about solar systems.

[Almot]

It's not like you are in tropical rainstorms area. Coil the pigtails and/or long MC4 extension and hide connectors under the panels.

[howardwheeler]

Should I follow MEX's advise and put electric grease in the connectors? I thought they were o-ring tight. I can surely do it if it is advisable. I really don't want to get back up on my roof any more than absolutely necessary.

[Almot]

mike-s wrote:
For a large fixed system putting hundreds of volts and tens of amps through them, sure - stick to one brand.

I recall, they are installing 3*315W in parallel. So - yeah, about tens of amps 🙂

Brand and monopoly aside, MC4 clones from questionable sources like Ebay are very often hit and miss. From a biggie like CS it should be TAD better.

In the worst case, you can get a crimper and replace T4 with MC4 if any issues arise. Hide them under the panels, they will last longer. If Mex were reading this, he would've probably told to smear it all with dielectric grease or Lanolin. In humid environment I would do this.

Yes, Amphenol headquarters are in the US. TUV protocol (of their H4 testing) is by Germans.

As said, no tools are required for disconnecting MC4 and its clones. Not "very" easy after it's been sitting for more than year, collecting dust and salt deposits, but doable - with bare fingers. I would not replace T4 with a connection directly to panel unless this could be done without soldering. It's better to keep it detach-able. I would not replace T4 with Anderson, unless frequent disconnecting is in plans, like using them in a portable setup. Definitely would not replace T4 with SAE.

[Tom_M1]

howardwheeler wrote:
I've never hooked up solar panels before and now face two different connectors: T4 and MC4. Is one better than the other or more suitable for particular applications? And most important, do they plug into one another, in other words, can you have a mixed system where, for example, a T4 connector on a panel must mate to a MC4 connection on an extension cable?

If you are doing a rooftop permanent install you would not need connectors. Most panels have a junction box on the back which would give you access to a terminal strip. Remove the pigtail wires and hook direct to the terminal strip.

I have two panels that I can remove and set in the sun. I cut the MC4 connectors off and replaced them with Anderson Powerpole SB50 connectors.

[shelbyfv]

I was concerned about using the MC4 connectors until I tried them. They are easy enough to unplug w/o the tool.

[mike-s]

It's common to use 2 contact SAE connectors (they're like the common 4 wire flat trailer connectors). You can find them with 12 ga wire, which should be good for a couple of 100W panels, albeit with some loss. It's pretty common to find them pre-installed on RVs as part of a "solar ready" package. But, they're usually just wired straight to the battery, and the portable panels are expected to have their own controller.

[brulaz]

Since we're talking about solar panel connectors, is there something out there that's designed to be connected/disconnected more frequently?

The mc4s (or equiv) don't seem to be designed for it. I've got the tool to disconnect but still ...

Thinking about a portable solar system. Perhaps just regular 120VAC connectors? Or something a bit more waterproof?

[mike-s]

MC4 is a proprietary connector made by the company Multi-Contact (now Staubli). T4/H4 and others use the same form factor. Because the MC4 is proprietary, there is no industry spec that all the variants are built to which guarantees compatibility and interoperability. They're all based off the original MC4. But Multi-Contact does what they can to keep the market to themselves, including dire warnings that the earth will be riven asunder and death and destruction will result if they're interconnected with competitors products.

I wouldn't worry about T4/H4/MC4 FUD at all for an RV scale system. For a large fixed system putting hundreds of volts and tens of amps through them, sure - stick to one brand. But if you're putting a few panels on an RV, and they come with "MC4" type connectors already installed, I wouldn't worry about finding connectors from the same manufacturer to complete the system. They're all made to be interoperable, despite the dire warnings.

Not sure why Almot thinks Amphenol is German - their original name was American Phenol, and they're US (they do manufacture worldwide). Staubli is Swiss. T4s are made by Tlian, a Chinese subsidiary of Canada Solar.

[Almot]

Yep, "comparable" 🙂

T4 must be the product of CS Chinese partners. There is also H4 by Amphenol company in Germany, and if you check Ebay, you'll also find "PV4 MC4" from nameless and countless Chinese factories. Unlike MC4, none of those is UL approved, and neither is mating MC4 with others. Though Amphenol took pains to test according TUV standards and submitted reports saying that H4 are fully compatible with MC4.

I guess you can plug it in.
"Better"? Who knows... Wouldn't bet my life on it.

Edit - PS:
it's always a good idea to tuck the connectors under the panel, away from rain and UV, be it original or "comparable".

[BFL13]

Data sheet says MC4 or "MC4 comparable."

https://d1819pwkf4ncw.cloudfront.net/files/documents/datasheetquartechcs6x-pen-259377.pdf

[howardwheeler]

As a look alike, do they plug into one another? I have Canadian Solar panels with T4 connectors coming and have all my cables with MC4 connectors that I got from Unlimited Solar.

[Almot]

howardwheeler wrote:

Is one better than the other or more suitable for particular applications?

I doubt than one is really "better" than another. MC4 is older and is an industry standard, UL approved. T4 is a look-alike from Canadian Solar subsidiary.