[RE-wrenches] PSA: Schuco recall and broader polyamide backsheet defect (2010-2014 era)

Tue May 5 14:47:05 PDT 2026

Interesting.  I installed some of those manufacturers between those dates.
The company I was working for from 2010 to 2019 is no longer in business,
and I lost all my email from there, so don't even have good records of the
customers then, though I probably have all of the permit drawings on some
old hard drive still.  These installs were in Colorado, so a much drier
climate than Vermont, but still, there are wet days...

Zeke

On Tue, May 5, 2026 at 1:25 PM <re-wrenches-request at lists.re-wrenches.org>
wrote:

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> Today's Topics:
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>    1. PSA: Schuco recall and broader polyamide backsheet defect
>       (2010-2014 era) (Nicholas Ponzio)
>    2. Fortress Envy CTs on 200 amp wire (William Miller)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 5 May 2026 12:14:48 -0400
> From: Nicholas Ponzio <nponzio at buildingenergyus.com>
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
> Subject: [RE-wrenches] PSA: Schuco recall and broader polyamide
>         backsheet defect (2010-2014 era)
> Message-ID:
>         <
> CADR8m8juMPgDtzAYoTWoBAjqzar-HGcjhi1_9v1HT4HA8xLrgQ at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Wrenches,
>
> Sharing a finding from this week that I figure plenty of you are running
> into and may not have connected the dots on. I know I hadn't until
> yesterday.
>
> We pulled an old array off a roof in Vermont. Not our installation. Modules
> were Schuco, vintage ~2010. Client asked about reinstalling vs. replacing,
> and that question sent me down a rabbit hole.
>
> It turns out Schuco issued a formal product safety warning in 2022 covering
> modules delivered from 2010 to 2014. The polyamide backsheet from a
> specific supplier can develop chalking and cracking along the internal cell
> connector. When this happens, the panel frame can become electrically live.
> Critical detail: inverter shutdown does NOT eliminate the hazard while the
> panels see sunlight. The manufacturer's own remediation guidance is to
> uninstall and dispose of panels. UK Government issued a formal product
> safety alert (2211-0050).
>
> That alone was news to me. But the bigger story is that this is not a
> Schuco-specific defect. The polyamide backsheet failure mode is
> industry-wide for the 2010 to 2014 era. DuPont's 2019 field reliability
> study estimated 12 GW of field failures from PA backsheet through-cracks.
> Schuco is unusual in that they actually published a recall. Most of the
> other affected manufacturers either went out of business (Solon, Scheuten,
> Conergy, Suntech) or quietly handle replacements case-by-case without
> public notification. Trina, Yingli, early Canadian Solar, Jinko, Renesola
> all show up in field failure literature for this era.
>
> Why I'm posting:
>
> 1. We've installed a few of these brands in that window ourselves. I'm now
> building an outreach list to proactively notify those clients. I'd be
> surprised if I'm the only one in this group with legacy 2010 to 2014
> systems that warrant a second look.
>
> 2. Symptom that prompted me to dig deeper: we've had multiple clients this
> winter reporting intermittent DC ground faults, mostly in cold/wet
> conditions, that clear up in dry weather. Classic signature of insulation
> breakdown in cracked PA backsheets. Insulation resistance drops with
> moisture, recovers when dry. If you're seeing winter-correlated GFDI events
> on legacy systems, this is worth checking before chalking it up to age.
>
> 3. Field protocol matters. Treat suspect arrays as energized regardless of
> inverter state. Insulated gloves, photograph nameplates and serial numbers,
> and document backsheet condition. Visual cues: chalky white residue, fine
> cracks between cells, yellowing, powdery feel when wiped.
>
> 4. For confirmed-recall modules (Schuco MPE in the affected serial range):
> do not reinstall. Manufacturer guidance is to uninstall and dispose. For
> other PA-backsheet modules without a formal recall, treat the decision as
> an engineering judgment call. Visual inspection (chalking, cracking,
> yellowing) plus insulation resistance testing should be your minimum bar
> before considering reuse. My personal bias is heavily against reinstalling
> any 10+ year old PA-backsheet module given the cost of labor vs. the risk
> profile, but that's a business call, not a safety mandate.
>
> References for anyone who wants to dig in further:
>
> - Schuco product warning (2022): solarpowerportal.co.uk article "Sch?co
> issues product warning over potential defect in solar modules"
> - pv-magazine coverage of the expanded warning (Nov 2022)
> - UK Gov product safety alert 2211-0050
> - DuPont 2019 Global Field Reliability Study (12 GW failure estimate)
> - ScienceDirect, Eder et al, "Error analysis of aged modules with cracked
> polyamide backsheets" (2019)
>
> I searched the list archive and didn't see this come up before. If I missed
> an earlier thread, apologies for the duplication. Otherwise, I'm curious
> whether others are seeing the winter ground fault pattern, and how folks
> are handling client communication and remediation scoping on these legacy
> systems.
>
>
>
> --
> Nicholas Ponzio
> Building Energy
> Williston, VT 05495
> http://www.BuildingEnergyVT.com <http://www.buildingenergyvt.com/>

-- 
Zeke Yewdall
PV Engineer
NABCEP #031508-89
zeke at darkforestsolar.com
303-523-3592
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