[RE-wrenches] Cable sizing for high current modules? NEC interpretation/guidance?

Fri Nov 10 08:25:47 PST 2023

It was explained to me, the compounds Amphenol used in this large batch of connector housings were bad/incorrect.

We started seeing failures on these modules as quickly as 6 months of being in service.

Bryan Norkunas
PV-Cables

Get Outlook for Android<https://aka.ms/AAb9ysg>
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From: RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> on behalf of Jay via RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Friday, November 10, 2023 7:39:43 AM
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Cc: Jay <jay.peltz at gmail.com>
Subject: Re: [RE-wrenches] Cable sizing for high current modules? NEC interpretation/guidance?

I’ve wondered what other variables are at work given that mostly these connectors work as they should.

I’d like to see them come with plugs covering the openings. This would keep dirt, salt air, moisture, etc  out until they are connected.

As to if there were lots of failures with SW modules then I wonder if whoever built the whips had poor quality control. Might be they were not seated properly or dirty or the crimp they used wasn’t calibrated correctly or they were stored in a salt environment creating corrosion or something like that.

I looked up the specs last night on the mc4 and it’s like 30+ amps depending on the wire, pretty impressive

Jay

On Nov 10, 2023, at 5:53 AM, Dave Tedeyan via RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:

Mine was a roof mount. We had very few SolarWorld projects. In fact, this might be our only one.

On Fri, Nov 10, 2023, 8:10 AM Chris Schaefer via RE-wrenches <re-wrenches at lists.re-wrenches.org<mailto:re-wrenches at lists.re-wrenches.org>> wrote:
I'd be curious to know of the connector failures y'all have experienced, were the majority of these roof mounts?
Just wondering if with better air flow like that of a pole/ground mount, if that helped to minimize connector failure.

Christopher

On Fri, Nov 10, 2023 at 1:21 AM Bill Battagin via RE-wrenches <re-wrenches at lists.re-wrenches.org<mailto:re-wrenches at lists.re-wrenches.org>> wrote:

Ray,

            Exactly the same thing happened for me on a ground mount system, 3500 feet elevation the the Sierras so open cooler air, fully engaged MC4 factory connectors PV to PV connectors with SW285's, not passing current, melted.  No attempt to contact SW just made up new connectors.

            My calculation is with anything that is no doubt made up by the bazillion with a machine (connectors, light bulbs, pencils, chicken nuggets, etc) you're going to get some duds.  In 20+ years of installing PVs with factory made-up connectors, I've only seen this happen 2-3 times.  Installing in the mountains we no doubt use ground mount much more often than most installs in urban areas which would make a hot, melted connector possibly more of an issue a couple inches above a comp or wood roof.  We've never seen any connectors fail beyond the melted/deformed but still "contained" stage .

            Back when SW was first transitioning from one connector to another, I remember them saying they (I think it was UTX and MC or was it UTX and Amphenol?) were compatible.  We NEVER mixed connectors despite their claim.

Bill

Feather River Solar Electric
4291 Nelson St. (Shipping)
5575 Genesee Rd. (USPS, UPS)
Taylorsville, CA  95983
530-284-7849, 258-1641(cell)
CA. C10 Lic # 874049
Solar Powered since 1982
Home of the Sunny Side Up

On 11/9/2023 4:31 PM, Ray Walters via RE-wrenches wrote:

I'm trying to find a pic to post, but they were MC4 connectors, not the UTX.

Ray

On 11/9/2023 4:57 PM, Brian Mehalic wrote:
Are they the Amohenol UTX connectors? SW had a recall on them, sounds like about the right timeframe.

<https://pv-magazine-usa.com/2017/03/29/solarworld-recalls-amphenol-connectors-sold-with-pv-modules/>
[X]
BREAKING: SolarWorld recalls PV modules with Amphenol connectors<https://pv-magazine-usa.com/2017/03/29/solarworld-recalls-amphenol-connectors-sold-with-pv-modules/>
pv-magazine-usa.com<https://pv-magazine-usa.com/2017/03/29/solarworld-recalls-amphenol-connectors-sold-with-pv-modules/>

Brian

On Nov 9, 2023, at 4:47 PM, Ray Walters via RE-wrenches <re-wrenches at lists.re-wrenches.org><mailto:re-wrenches at lists.re-wrenches.org> wrote:

12 Ga wire is not going to catch on fire, but the MC connectors might.  I just went back on a 7 yr old Solarworld install, and had a bad series MC connector (module to module).  It got quite crispy, deforming and bubbling the plastic on both sides of the connection.  It was still passing current; I didn't get a chance to measure the volt drop.  It was completely plugged in, so not an installation issue.

This was not one of our connectors made up in the field, these were Solarworld factory connectors on both sides, same model modules.  That also means no mismatch of "MC4" connector type.

10+ amps continuous, moist environment, 30F+  hotter than ambient temp, all are tough on connectors.  I predict more connector failures as module current ratings increase.

Ray Walters
Remote Solar

On 11/9/2023 3:02 PM, Glenn Burt via RE-wrenches wrote:

Good luck trying to convince your customer that their house caught on fire because of a manufacturers flaw, and you have no responsibility for it…

It may be an out to shift the blame, but it only makes everybody get some on them…

From: RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org><mailto:re-wrenches-bounces at lists.re-wrenches.org> On Behalf Of William Miller via RE-wrenches
Sent: Wednesday, November 08, 2023 12:14 PM
To: RE-wrenches <re-wrenches at lists.re-wrenches.org><mailto:re-wrenches at lists.re-wrenches.org>
Cc: William Miller <william at millersolar.com><mailto:william at millersolar.com>
Subject: Re: [RE-wrenches] Cable sizing for high current modules? NEC interpretation/guidance?

George:

Appliance manufacturers have their own requirements that are not the same as the NEC requirements.  As long as you are not modifying the manufactured assembly you are not responsible for compliance of that appliance.  By appliance, I mean the solar module, microinverter, etc.

William Miller

Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com<http://www.millersolar.com/>

CA Lic. 773985

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org<mailto:re-wrenches-bounces at lists.re-wrenches.org>] On Behalf Of George McClellan via RE-wrenches
Sent: Wednesday, November 8, 2023 9:06 AM
To: RE-wrenches
Cc: George McClellan
Subject: [RE-wrenches] Cable sizing for high current modules? NEC interpretation/guidance?

Team;

With the move to larger cells, some modules have an Isc that is pushing the limits of 12 AWG wire.  If I apply the rule of 156% (or 125% solar derate*125% continuous load derate) to an 18 Amp Isc module this will exceed the 25A that a 12 AWG wire can carry.  I understand that the homeruns will need to be a larger AWG (10 ga), but do the solar module cables (from junction box to MC4) also need to be larger?  Any guidance or reference material would be greatly appreciated.

Thx,

George McClellan | Senior Technical Sales Manager | REC Americas LLC

330 James Way Ste 150 | Pismo Beach, CA 93449 | USA

Cell phone +1 805 704 3226 | Fax +1 805 357 6104

www.recgroup.com<http://www.recgroup.com/> | george.mcclellan at recgroup.com<mailto:shannon.kent at recgroup.com>

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