[Bug]: Sofar - HYD 15KTL-3PH (LSE-3-USB) ExceptionResponse at register 0x9020 during battery setup

[Rocketjumper018]

Describe the bug

After updating past version 2026.07.1, the solax_modbus integration fails to set up sensors for my Sofar inverter.

Integration Version

2026.08.2

Homeassistant core version

2026.8.2

Inverter brand

Sofar

Plugin used

plugin_sofar.py

Serial prefix

SP1ES1

Connection Method

LSE-3-USB adapter - Modbus TCP over Port 8899

Detailed Error Log

Error while setting up solax_modbus platform for sensor: Sofar: multi-function single-register write was rejected by device 1 at register 0x9020: ExceptionResponse(dev_id=1, function_code=144, exception_code=3)
Traceback (most recent call last):
File "/usr/src/homeassistant/homeassistant/helpers/entity_platform.py", line 499, in _async_setup_platform
await asyncio.shield(awaitable)
File "/config/custom_components/solax_modbus/sensor.py", line 210, in async_setup_entry
if not await battery_config.select_battery(hub, batt_nr, batt_pack_nr):
File "/config/custom_components/solax_modbus/plugin_sofar.py", line 4128, in select_battery
await hub.async_write_registers_single(unit=hub._modbus_addr, address=self.bms_inquire_address, payload=payload)
File "/config/custom_components/solax_modbus/init.py", line 1564, in async_write_registers_single
return await self._async_transport_write(...)
File "/config/custom_components/solax_modbus/init.py", line 1479, in _async_transport_write
return self._validate_write_response(...)
File "/config/custom_components/solax_modbus/init.py", line 1378, in _validate_write_response
raise HomeAssistantError(f"{self._name}: {operation} was rejected by device {unit} at register 0x{address:x}: {response}")
homeassistant.exceptions.HomeAssistantError: Sofar: multi-function single-register write was rejected by device 1 at register 0x9020: ExceptionResponse(dev_id=1, function_code=144, exception_code=3)

Additional context

• Battery Setup: Pylontech Force H2 (BMS V1)
• Connection Type: Modbus TCP over Ethernet (LSE-3-USB adapter / Port 8899)
• Modbus Address: 1 (default)
• Rollback Test: Downgrading to version 2026.07.1 resolves the issue completely and sensors set up as expected.
• Notes: The error occurs during the battery selection routine (select_battery) when writing to register 0x9020.