MC4 Connectors - I think they are bad

[kp_utah]

So, I had another post going months ago, but it was about finding the issue. I am pretty sure now my issue is the MC4 connectors...

To review from before, I was having issues with no voltage registering on my charge controller. I am almost postive its a short of some sort between my junction box on the roof to the panels, which are connected with MC4 connectors. I get full voltage from both of my 100 W renogy panels if I take off the Y-connectors and measure at the pigtails of each panel.

My only hesitation, at times, if I put the connections all back, then sometimes i get full voltage all the way into the charge controller. So, i think its fine, but its not. then I go on a trip, it works for 1-2 days, then fails again. I get on the roof, unhook the mc4 connectors, measure, and it works now, then i put them all back together, and it works again. So.... My only conclusion is that me moving around the wires, disconnecting, reconnecting, moves them around enough to fix (temporarily) the bad connection.

I am guessing its the MC4 connectors, or the connection of the pigtail into the panels. I would really prefer to NOT take off the panels, as they are fastened with those Z brackets (yes I know that as a mistake).

So, my next quest is to remove the MC4 connectors. However, now the pigtails will not reach the junction box. So, I have 2 choices, create a new junction box, or somehow combine the wires on the roof outside of a junction box. I assume that is a bad idea and not recommended. Any thoughts? Or should I rip up the panels, and get to where they connect into the panels and attempt to wire from that point to my existing junction box. I don't even know if that is possible with these renogy panels. I can't see under it now, to tell.

Thoughts??? Would a butt splice work in the elements? How do I do join the 3 wires outside a junction box and in the weather? Or is that a bad idea?

[kp_utah]

well... success. I replaced my MC4's. I cut them off and routed things directly to a junction box on the roof. Problem solved. I have all 21-22 volts now. Perhaps I could have looked for authentic MC4 connectors and replaced my old ones w new ones. I already had a junction box on the roof since my 5th wheel came pre-wired already to the roof.

[wyocowboy00]

I found when putting together my solar system that it is easy to not get the connectors pushed all the way (and locked) into the MP4. Then when you put the MP4s together (plugged into each other), it pushes the connectors back and causes a bad connection. On my solar installation I had one of the leads from the roof to the controller wide open. It turned out to be a connector on a plug (about right in the middle of the wire run) that had not been seated corrected and got pushed out the back of the plug. You may have a connector that is just barely making contact.

[MEXICOWANDERER]

What is wrong with Weather Pak? Never had one fail.

[time2roll]

Hard to determine exactly where the issue is. Instead of fiddling to make it work, need to fiddle with it to make it fail. Much easier to find the poor connection.

Since the panels are Renogy I would trust their parallel connectors. Also the connector on the feed wire is suspect.

[kp_utah]

So mine would be an open circuit then. not a short circuit.

So, even the MC4 directly from Renogy have the red rings:

https://www.amazon.com/gp/product/B00Q5W30FY

[mike-s]

Nice marketing picture. Multi-Contact (the MC in MC4) does all they can to keep the market to themselves. Contrary to what their graphic implies, there are other quality connectors using the same form factor. Amphenol makes the H4. Canadian Solar makes the T4. SMK makes the PV-03. There are probably some decent Chinese ones, but finding which ones is likely a **** shoot.

Best to keep to connectors from the same manufacturer if near the limit (~40A/600V). Don't bet that your panels use real MC4s, either.

[time2roll]

The above is just a random image from google

I got mine at solarblvd.com and they seem to be authentic. Solarline is the brand posted.

https://www.solarblvd.com/products/female-solarline-2-locking-8211-fits-mc4-cable-on-module/

[corvettekent]

time2roll wrote:
Do the connectors seem legit?

Very interesting, I just check my MC4 connectors, they all have red O rings even my USA make panels.

[MrWizard]

"Open circuit" aka bad connection

No power going where it is suppose to go is an open circuit

A short circuit leads to something melting and burning

[kp_utah]

wow. no, they have the red ring. Interesting!! Sounds like counter-fits. I don't recall where I got them. I wonder if I have a lose fit inside. I have done a fair amount of tugging on these, trying to move them around and get them to where I could work on them.

[time2roll]

Do the connectors seem legit?

[kp_utah]

I have a morningstar TriStar-PWM-45.

[hedge]

What controller do you have, any chance you could just wire the panels in series?

If you want to stay with parallel then I think you'll need to come up with some sort of junction box. I made my box to accept mc4 connectors but lots of ways to do it.