Could be moisture accumulation in the conduit over the years along with a minor insulation damage.I am tracing a similar intermittent on an Aurora roof mount. Incompatible MC connectors are my first pass at repair, however has also not corrected the issue.Only fails after rain.IRT testing did not reveal any clue, but it is hard to coordinate testing availability with weather conditions.Original installer long gone...-GlennSent from my 'smart'phone, so please excuse typos and spelling errors.------ Original message------From: Dave Tedeyan via RE-wrenchesDate: Wed, Dec 13, 2023 10:52 AMTo: RE-wrenches;Cc: Dave Tedeyan;Subject:[RE-wrenches] SMA TL-22 insulation resistance errorHi All,I am curious to hear if anyone else has run into this:This is the system I posted about a little while ago that had the SolarWorld modules and all the module to module connectors were swollen and melted. One of the inverters was giving an insulation resistance error, and so after seeing the module connectors, I was sure that was the issue. We replaced every single module connector with new MC4's, and then the error came back!My next step was to swap in the junction box which strings go to which inverter to identify whether the issue was on the roof or somewhere between the roof jbox and the inverter. (the issue was isolated to only 1 of 4 strings previously). Turns out the same inverter is faulting, which leads me to believe that there may be an issue with the wires in the DC conduit. Maybe they got damaged by a rough wire pull at the initial installation 7 years ago, and its finally degraded enough to cause a problem. The fault is intermittent, only showing up once every couple weeks or so, so it is difficult to catch it while the fault is active. But my question is, could there also be something wrong with the inverter itself? After spending a lot of time on this one, ideally, I would know that replacing the DC wires will fix it. So I am curious if people have done this, t o still find that the issue was something internal to the inverter.Thanks!-Dave-- Dave Tedeyan, P.E.Owner | Sungineer Solarp: he | him | hisa: 1653 Slaterville Rd. | Ithaca, NY 14850w: www.sungineersolar.comc: (607) 270-0370
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