Hi Jason - It certainly appears that there was some sort of surge or short. We've had a few cases where microinverter branch circuit end termination caps were left off or fell off and shorted out during rain storms. You might want to double check that those are all in place. We've also had cases were microinvers themselves developed internal shorts. This third comment is only anecdotal - I've been in touch with a couple of other installers that have had back-fed breaker issues specifically with Eaton brand breakers burning up the bus stabs. Our company has had one unexplained issue where the inverter output breaker bus stabs were burned up with Eaton breakers. I have no idea whether the breakers were faulty or what, but thought I'd just mention it in case there is a pattern.
Best, August Luminalt On Tue, Jan 21, 2020 at 9:10 AM Jason Szumlanski < ja...@floridasolardesigngroup.com> wrote: > (System installed by another contractor...) > > I have been tasked with assisting in the investigation of damage in a > subpanel used to combine inverter output circuits (5 strings of > microinverters). There appears to be no damage to conductors or other > system components. It looks like the damage started at the stabs of the bus > bar where the breakers connect. Picture attached. Here are a few clues: > > - Monitoring indicates that damage occurred overnight a few weeks ago. > That night we had rain as a winter front came through Florida, possibly > lightning. The prior day everything was fine. > - The next morning, only 2 of 5 strings started producing power, but 4 > of 5 strings were reporting data to the Envoy. The two strings that were > reporting but not producing power reported 0Vac and Voc on the DC side of > the microinverters. > - A couple of weeks later, 1 of the 2 strings that was producing power > quit doing so, but continued reporting data. > - Customer discovered damage yesterday. > - About a week before the initial damage apparently manifested itself, > another contractor installed a whole house generator transfer switch on the > line side of the PV interconnection. The generator has never been run > (there is not even a LP fuel source on site yet). I pointed out that the > solar interconnection, which was previously on the supply side, would need > to be moved to the supply side of the generator transfer switch's main > breaker before operation. During the transfer switch installation, the > contractor also switched line 1 and line 2, but that shouldn't > really matter, except for Enphase consumption monitoring, which was messed > up by the swapping of the lines. > > So I'm looking for ideas. I'm wondering if the OCPD would be a likely > place for lightning damage to manifest itself. I can't visually detect any > other damage anywhere else. I can't imagine that the transfer switch > installation would have anything to do with it, but the timing is > interesting. Other than replacing the subpanel and OCPD and firing it back > up (no pun intended), I'm not sure how to approach further investigation. > > Jason Szumlanski > Florida Solar Design Group > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > >
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