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?

[shelbyfv]

I don't understand this about needing a tool either. It could be an "issue with the writing" or it could just be wrong.

[MEXICOWANDERER]

I used Weather Paks in 1990 on the 4 Kyocera 51 watt panels on Quicksilver. Space Shuttle Endeavor/Discovery surplus refit wire from Lockheed. It's like brand new 27-years later. I literally "filled" the connection boxes with dielectric silicone grease then forced grease into all the panel seams. Reminds me - I need to replace the green fishnet coconut deflector on the roof.

[Almot]

mike-s wrote:
A tool most certainly is required for disconnecting them. Since 2008, the NEC requires it

Is it really that difficult to understand what people mean? A "complete disconnect" ... from reality 🙂

[Almot]

Mex, there is a decent o-ring already in place in original MC4. Can't say about clones - a better clone will likely have it too.

[MEXICOWANDERER]

First I slip on the silicone o-ring.

I solder the Weather Pack pins onto the wire. Coat the pins in silicone grease and grease the o-ring. So when things are assembled, every bit of metal is overlaid with silicone grease.

If I want to get carried away, I slop on heavy duty silicone spray lube over the joined connector pair.

I'm lazy. As far as I'm concerned "repair work" means 7-year old work is like it happened "yesterday". But I use the convenient and politically correct excuse that lazily performed work that "fails too soon"is environmentally unconscionable landfill fodder. Waste of resources. Contributes to Global Climate Motormouth.

[mike-s]

Almot wrote:
TUV is an international testing and certification body. No remarks on affiliation have been made.

Hard to say.

Almot wrote:
There is also H4 by Amphenol company in Germany...
TUV protocol (of their H4 testing) is by Germans.

That last statement isn't in understandable English, so it's not clear what was meant. It was your response when it was pointed out that Amphenol wasn't German as you claimed, and seemed to be some kind of support for that claim. That's an issue with the writing, not the reading.

[howardwheeler]

Got it. Thanks. I'm in the next couple of days going to be assembling everything except hooking up the panels. All wiring is run, but the panels won't be picked up till tomorrow when my friend gets them in Massachusetts. I'm in Texas, so the panels will be brought down in around a week and I should wrap it all up. I much appreciate all the advice and tips. I think I'm in the closing segment of this project.

[Almot]

I would think - yes, down the hole. You don't want much grease on the outside, will make handling it difficult. Mex is in tropics, much more harsh environment.

[howardwheeler]

So Mex, I should coat the MC4 to T4 electrical connections with silicone grease. Since you can't actually get at the metal conductors themselves, I guess I would smear some down the holes and when pressed together it should cost the connection. Correct?

[MEXICOWANDERER]

I use Weather Pak® connectors. They are submersible. Easy to disconnect. Weather Pak can use three pin sizes, 22-18 ga. 16-14 ga. or 12-10 gauge. Black. UV proof nylon. Incredible strength against accidental pull-apart. To disconnect, no tools needed. Use a finger under the tab and pull. Silicone grease makes this even easier.

The ONLY connectors that I consider to not need silicone grease, use GOLD plating. Copper, bronze, brass, tin and silver plating all tarnish meaning oxidize. When things become coated with oxide resistance goes up. And with these materials oxidation keeps thickening. I have seen tinned wire and tinned terminals turn black. Tin oxide.

[Almot]

mike-s wrote:
{TUV} it's not affiliated with Amphenol in any way, other than that Amphenol may use their services,

They may, and they did use it. TUV is an international testing and certification body. No remarks on affiliation have been made.

You responses show a lack of reading/comprehension skills 🙂

Tools are hardly necessary to disconnect MC4. Haven't hear of anybody being unable to do this without tools. "Required" by NEC - don't know, don't care. This is my system. Just squeeze the sides to disconnect. Easy when new and clean, more difficult after being exposed to elements.

[Almot]

mike-s wrote:
You never said which panels or controller,

He's been at it for a while. You would've known if read his previous threads. Parallel-serious has also been discussed.

[shelbyfv]

mike-s wrote:

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.

I guess I don't understand either. I squeeze the little tits with thumb and forefinger of one hand, pull the thing apart with the other. I have the little tool but I didn't know I was required to use it.

[mike-s]

You never said which panels or controller, but given the controller limitations, sounds like you did it right.

Seems you're using 72 cell panels. Yeah, those can go over 50V open circuit per when you go below freezing. If you're using full power, they'd normally run at around 37V/9A.

They're considered 24 volt panels. There are also 60 cell panels, which are considered 20 volts, but are sometimes called 24 volt ones just to distinguish them from 12 V panels. It's confusing.

36 cell = "12 volt" = ~22.5 Voc
60 cell = "20 or 24 volt" = ~37.5 Voc
72 cell = "24 volt" = ~45 Voc