Another MC4 failure

[Mattb4]

Just when you think you have everything perfect something comes up. Yesterday afternoon after my battery bank was fully charged I happened to glance at the SCC for array #4 and noticed PV indicating it was nighttime at zero incoming volts. This array consists of 2-200W panels wired in series which are about a year old now. Starting from the SCC to PV breaker and working out I looked for a loose connection . When I wiggled the MC4's between the 2 panels I noticed that my PV voltage was back.

Pulling them apart I noticed the distorted plastic on the male MC4. It had obviously been heating up in that area. Nothing for it but to replace both panels MC4's. The Corresponding female MC of the other series connected panel showed the signs of corrosion. Considering it has not rained here for almost 2 months it was odd that it just happened to fail yesterday but that is how it goes.

New MC4's in place I am back in business. Good idea to have on hand spares and the tools needed to work on them.

 

[SparkyJJO]

Same brand of panels so they should even be the same connectors right?
Man these things seem like such crap. Who designed this... (rhetorical question)

 

[CMDRZOD]

I ended up cutting all my MC4's off and using crimps and heat shrink for my roof mounted arrays. For this exact reason. I have little faith in the longevity of MC4 connections. If they were easily reachable on a ground mount array I might have kept them. Ended up being around 200 crimp and heat shrinks but I trust those connections far more.

I've been an electrician 20 years in March. I've yet to see a properly crimped connection fail in my career.

 

[Lprantner]

Same brand of panels so they should even be the same connectors right?
Man these things seem like such crap. Who designed this... (rhetorical question)

I have 20 SSG 250w panels from SanTan Solar; one set of ten have MC4's that do NOT fit the MC4's on the second set of ten. Go figure.

 

[T-Rex]

More nightmares.... Reading this forum has me concerned about every part of my project. As I have mentioned before, for the first year or so, everything will be outdoors (weather protected of course) so when the fire starts, it'll be easier to put out.

 

[wildbillpdx]

I ended up cutting all my MC4's off and using crimps and heat shrink for my roof mounted arrays. For this exact reason. I have little faith in the longevity of MC4 connections. If they were easily reachable on a ground mount array I might have kept them. Ended up being around 200 crimp and heat shrinks but I trust those connections far more.

I've been an electrician 20 years in March. I've yet to see a properly crimped connection fail in my career.

Mind sharing what crimp connectors you are using?

 

[Chispas]

Cutting off the MC 4 connectors voids the warranty over here, but this is a heads up. On my tiny yurt system I have Weidmuller ( a snap together vesion of the MC 4 that needs no tools) to MC4 & I took ti apart the other day to pack away for the winter & one plug had water in it.

 

[CMDRZOD]

Mind sharing what crimp connectors you are using?

I used these crimps:

M10BCK | DigiKey Electronics

Order today, ships today. M10BCK – Terminal Butt Splice, Inline, Individual Openings Connector Crimp 10-12 AWG from 3M. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

www.digikey.ca

This is the heatshrink I bought:

HDT-0300-48A-BLACK | DigiKey Electronics

Order today, ships today. HDT-0300-48A-BLACK – Heat Shrink Tubing, Flexible 0.300" (7.62mm) 3 to 1 Black 4.00' (1.22m) from 3M. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

www.digikey.ca

Then I purchased this crimper to ensure good connections, 1.5 ton.

https://new.abb.com/products/7TAA131170R0002/bat22-6nv2

The die used with these crimps:

https://empower.abb.com/ecatalog/ec/EN_CA/p/DIE2002

(Picture shows crimp for insulated terminals on that site.)

Hope this helps!

All of my rapid shutdown and panel cables are #12. I have #10 home runs to combiner boxes in attic.

 

[matttelz]

I have 6 100W panels in my setup and I was moving the panels the other day. I noticed on my MPPT controller I was only getting ~180W in full sun, mid-day with mid 60's for temperatures. Did some wiggling of the MC4 connectors and walla, back up to ~500W.

I'm pretty sure MC stands for Mega Crap.
Can't wait to get rid of mine also.

 

[Patdufo1]

I think when I rewire my system, I might try a very large string tape over the whole connection. That way it can’t pull apart and it should be well sealed and still be good for warranty. Have to buy this heat shrink online because the big stuff is very expensive at Home Depot, or maybe Harbor freight

 

[Patdufo1]

I think when I rewire my system, I might try a very large string tape over the whole connection. That way it can’t pull apart and it should be well sealed and still be good for warranty. Have to buy this heat shrink online because the big stuff is very expensive at Home Depot, or maybe Harbor freight

Was supposed to say heat shrink tube

 

[JRH]

More nightmares.... Reading this forum has me concerned about every part of my project. As I have mentioned before, for the first year or so, everything will be outdoors (weather protected of course) so when the fire starts, it'll be easier to put out.

Haaa.. good thought… every part of my whole system is from 30 + ft to 100 ft from my RV dwelling except the 50 amp shore power cord that hooks it to the RV inlet.

The panels are out in the field and all the electronic gear is in an insulated/ heated enclosed aluminum trailer..

If anything ever catches on fire , I probably won’t try to put it out unless it just started in a minor way…

But I don’t want it happening near me when sleeping , whatever the case…

J.

 

[Patdufo1]

I think when I rewire my system, I might try a very large string tape over the whole connection. That way it can’t pull apart and it should be well sealed and still be good for warranty. Have to buy this heat shrink online because the big stuff is very expensive at Home Depot, or maybe Harbor freight

I bought a set of red and black 1 inch diameter heat shrink tapes 4 feet long each from Amazon for like six bucks. I think when I redo my system in the spring, I will put them on.