Error/Warning '36' [INV overvoltage or overcurrent] appears simultaneously on different inverters

[iomax]

Probably something to look into ... Premise: 2 inverters (HM-350 with a panel facing ESE, and HM-400 with a panel facing WSW), as mentioned several times and for the reasons explained In, still running on firmware version 24.11.7.

Occasionally — and when I say occasionally, I really mean very occasionally — I get an error (or maybe I should call it a warning?) '36' [INV overvoltage or overcurrent]. Now, by itself this might or might not be unusual, but the strange thing is that this error/warning, which should theoretically indicate an anomaly specific to a single inverter, is actually reported on both inverters — often, maybe even always, at the same time.

Unfortunately, neither the 2s DTU polling interval nor the 5s MQTT publishing rate is enough to catch any anomaly or odd behavior ( and we can completely rule out cloud-edge or similar, since this also happens under 100% clear-sky, full-sun conditions ) on either the DC or AC side.

What seems really strange or peculiar is the fact that it (often?) happens simultaneously on both inverters, despite the panels facing opposite directions: one ESE, the other WSW

[Marc9485]

Ich hatte das gleiche Problem an einem Wechselrichter. Als ich nach der "Test-Phase" alle AC-Leitungen in 2,5mm² geändert und die Wechselrichter direkt an der UV angeschlossen hatte war das Problem beseitigt.

[iomax]

Sorry for the late reply. Maybe it's not the case here. The AC-side connection of the inverter has already been done with 3x2.5mm² cable, directly and dedicated to the main panel, since the initial installation, about three years ago.

[gitisgreat2023]

I agree with @Marc9485, most probably a wiring issue. Very frustrating to chase them, but just loosen and tighten all DC and AC connections again (check the blank areas are large enough, strip more if necessary), from the inverters to the main panel. Are these inverters on separate phases? If so I guess it might be the neutral line, or earth. When it gets warmer or cooler, sees some vibration, then it happens, maybe once a month, that's why you don't see a direct correlation with the weather conditions.