HYD 3600-ES (Firmware G410): Reproducible ID15/ID26 trips on abrupt load disconnect during battery discharge

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Hi all,

I’ve been running a custom Modbus monitor on my HYD 3600-ES (Firmware G410, 2022 unit, 2× AMASS GTX5000, 10.24 kWh) for about three weeks now — polling every 3–10 s over the LSW-3/Solarman-V5 stick, including the raw fault registers (0x0201–0x0205).

I’ve found a reproducible pattern: whenever a common household load of ~2000–2500 W (oven, kettle, irrigation pump) switches off abruptly while the battery is supplying a correspondingly high discharge current (typically −2000 to −2550 W), the inverter trips ID15 (HwAcOC) or ID26 (SwBusOVP) within seconds — confirmed via the raw fault bits (fault1 bit 14 / fault2 bit 9).

Typical sequence: load ~2700–2800 W, battery discharge ~−2000 to −2500 W, grid voltage unremarkable (238–246 V) → trip → recovery in <10 s.

On 08/08 I logged five such trips within 53 minutes (3× ID26, 2× ID15), all triggered by the same oven, with grid voltage staying normal throughout — so I can rule out a grid-side cause.

Has anyone else seen this? Any experience with whether firmware newer than V410 improves the control loop’s response to fast load steps? I’m considering reporting this to Sofar directly but wanted to check here first whether this is a known behavior.

Thanks!

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Does this have anything to do with Home Assistant?

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Fair point — I’m not using the HA integration directly (custom Python/pymodbus monitor), but the underlying mechanism is the same Modbus TCP access that the HA modbus integration uses on this inverter family, and the fault registers I’m reading (0x0201-0x0205) are the same ones people here use to build binary_sensors for fault states. Posted here because this seemed like the most relevant Sofar HYD community with Modbus expertise — happy to move if there’s a better place.