<div dir="ltr"><div>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... </div><div><br></div><div>Zeke</div><br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Tue, May 5, 2026 at 1:25 PM <<a href="mailto:re-wrenches-request@lists.re-wrenches.org">re-wrenches-request@lists.re-wrenches.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Send RE-wrenches mailing list submissions to<br>
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Today's Topics:<br>
<br>
1. PSA: Schuco recall and broader polyamide backsheet defect<br>
(2010-2014 era) (Nicholas Ponzio)<br>
2. Fortress Envy CTs on 200 amp wire (William Miller)<br>
<br>
<br>
----------------------------------------------------------------------<br>
<br>
Message: 1<br>
Date: Tue, 5 May 2026 12:14:48 -0400<br>
From: Nicholas Ponzio <<a href="mailto:nponzio@buildingenergyus.com" target="_blank">nponzio@buildingenergyus.com</a>><br>
To: RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a>><br>
Subject: [RE-wrenches] PSA: Schuco recall and broader polyamide<br>
backsheet defect (2010-2014 era)<br>
Message-ID:<br>
<<a href="mailto:CADR8m8juMPgDtzAYoTWoBAjqzar-HGcjhi1_9v1HT4HA8xLrgQ@mail.gmail.com" target="_blank">CADR8m8juMPgDtzAYoTWoBAjqzar-HGcjhi1_9v1HT4HA8xLrgQ@mail.gmail.com</a>><br>
Content-Type: text/plain; charset="utf-8"<br>
<br>
Wrenches,<br>
<br>
Sharing a finding from this week that I figure plenty of you are running<br>
into and may not have connected the dots on. I know I hadn't until<br>
yesterday.<br>
<br>
We pulled an old array off a roof in Vermont. Not our installation. Modules<br>
were Schuco, vintage ~2010. Client asked about reinstalling vs. replacing,<br>
and that question sent me down a rabbit hole.<br>
<br>
It turns out Schuco issued a formal product safety warning in 2022 covering<br>
modules delivered from 2010 to 2014. The polyamide backsheet from a<br>
specific supplier can develop chalking and cracking along the internal cell<br>
connector. When this happens, the panel frame can become electrically live.<br>
Critical detail: inverter shutdown does NOT eliminate the hazard while the<br>
panels see sunlight. The manufacturer's own remediation guidance is to<br>
uninstall and dispose of panels. UK Government issued a formal product<br>
safety alert (2211-0050).<br>
<br>
That alone was news to me. But the bigger story is that this is not a<br>
Schuco-specific defect. The polyamide backsheet failure mode is<br>
industry-wide for the 2010 to 2014 era. DuPont's 2019 field reliability<br>
study estimated 12 GW of field failures from PA backsheet through-cracks.<br>
Schuco is unusual in that they actually published a recall. Most of the<br>
other affected manufacturers either went out of business (Solon, Scheuten,<br>
Conergy, Suntech) or quietly handle replacements case-by-case without<br>
public notification. Trina, Yingli, early Canadian Solar, Jinko, Renesola<br>
all show up in field failure literature for this era.<br>
<br>
Why I'm posting:<br>
<br>
1. We've installed a few of these brands in that window ourselves. I'm now<br>
building an outreach list to proactively notify those clients. I'd be<br>
surprised if I'm the only one in this group with legacy 2010 to 2014<br>
systems that warrant a second look.<br>
<br>
2. Symptom that prompted me to dig deeper: we've had multiple clients this<br>
winter reporting intermittent DC ground faults, mostly in cold/wet<br>
conditions, that clear up in dry weather. Classic signature of insulation<br>
breakdown in cracked PA backsheets. Insulation resistance drops with<br>
moisture, recovers when dry. If you're seeing winter-correlated GFDI events<br>
on legacy systems, this is worth checking before chalking it up to age.<br>
<br>
3. Field protocol matters. Treat suspect arrays as energized regardless of<br>
inverter state. Insulated gloves, photograph nameplates and serial numbers,<br>
and document backsheet condition. Visual cues: chalky white residue, fine<br>
cracks between cells, yellowing, powdery feel when wiped.<br>
<br>
4. For confirmed-recall modules (Schuco MPE in the affected serial range):<br>
do not reinstall. Manufacturer guidance is to uninstall and dispose. For<br>
other PA-backsheet modules without a formal recall, treat the decision as<br>
an engineering judgment call. Visual inspection (chalking, cracking,<br>
yellowing) plus insulation resistance testing should be your minimum bar<br>
before considering reuse. My personal bias is heavily against reinstalling<br>
any 10+ year old PA-backsheet module given the cost of labor vs. the risk<br>
profile, but that's a business call, not a safety mandate.<br>
<br>
References for anyone who wants to dig in further:<br>
<br>
- Schuco product warning (2022): <a href="http://solarpowerportal.co.uk" rel="noreferrer" target="_blank">solarpowerportal.co.uk</a> article "Sch?co<br>
issues product warning over potential defect in solar modules"<br>
- pv-magazine coverage of the expanded warning (Nov 2022)<br>
- UK Gov product safety alert 2211-0050<br>
- DuPont 2019 Global Field Reliability Study (12 GW failure estimate)<br>
- ScienceDirect, Eder et al, "Error analysis of aged modules with cracked<br>
polyamide backsheets" (2019)<br>
<br>
I searched the list archive and didn't see this come up before. If I missed<br>
an earlier thread, apologies for the duplication. Otherwise, I'm curious<br>
whether others are seeing the winter ground fault pattern, and how folks<br>
are handling client communication and remediation scoping on these legacy<br>
systems.<br>
<br>
<br>
<br>
--<br>
Nicholas Ponzio<br>
Building Energy<br>
Williston, VT 05495<br>
<a href="http://www.BuildingEnergyVT.com" rel="noreferrer" target="_blank">http://www.BuildingEnergyVT.com</a> <<a href="http://www.buildingenergyvt.com/" rel="noreferrer" target="_blank">http://www.buildingenergyvt.com/</a>></blockquote></div><br><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr">Zeke Yewdall<div>PV Engineer</div><div>NABCEP #031508-89</div><div><a href="mailto:zeke@darkforestsolar.com" target="_blank">zeke@darkforestsolar.com</a></div><div>303-523-3592</div></div></div></div></div></div>