Auto-detect Modbus inverter serial number from device registers

README.md

@@ -120,6 +120,7 @@ Home Assistant only allows one `iot_class` value in the manifest. SolisConnect i
 **Inverter Serial**: (Required)
 
 - Enter your inverter's serial number. This is now **mandatory** for generating unique entity IDs and ensuring configuration stability.
+- On Modbus hybrid inverters, once connectivity is confirmed the integration reads the serial directly from the device and silently corrects a mistyped value (grid/string models don't expose this register, so the typed value is used as-is). On SolisCloud, the serial is optional and auto-resolved when your plant has exactly one inverter.
 
 **Poll Interval**:
 

custom_components/solisconnect/config_flow.py

@@ -45,7 +45,7 @@
 )
 from .data.enums import InverterType
 from .data.solis_config import CONNECTION_METHOD, SOLIS_INVERTERS, InverterConfig, inverter_options_from_config
-from .helpers import hmi_version_supports_v2
+from .helpers import extract_serial_number, hmi_version_supports_v2
 
 _LOGGER = logging.getLogger(__name__)
 
@@ -616,6 +616,26 @@ async def _validate_config(self, user_input):
                             )
                             user_input["has_v2"] = detected_has_v2
 
+                # Auto-detect the inverter serial from the device (registers 33004-33019,
+                # ASCII) rather than trusting only what the installer typed. Grid/string
+                # models don't expose this range, so skip there. A failed/garbage read must
+                # never block setup; the user's typed serial survives untouched.
+                if inverter_config.type not in [InverterType.GRID, InverterType.STRING]:
+                    try:
+                        serial_registers = await modbus_controller.async_read_input_register(33004, 16)
+                    except Exception as serial_error:
+                        _LOGGER.debug("Serial number read failed during setup; leaving serial as configured: %s", serial_error)
+                    else:
+                        if serial_registers:
+                            detected_serial = extract_serial_number(serial_registers).strip().upper()
+                            if detected_serial and detected_serial != (user_input.get(CONF_INVERTER_SERIAL) or "").strip().upper():
+                                _LOGGER.info(
+                                    "Detected inverter serial %s from device; overriding configured serial %s",
+                                    detected_serial,
+                                    user_input.get(CONF_INVERTER_SERIAL),
+                                )
+                                user_input[CONF_INVERTER_SERIAL] = detected_serial
+
                 return True, None
             except Exception as e:
                 _LOGGER.warning(f"Connection failed attempt {attempt + 1}/5: {str(e)}")

tests/test_cloud_integration.py

@@ -418,9 +418,17 @@ async def test_dual_flow_cloud_model_overrides_wrong_modbus_model(hass: HomeAssi
     from custom_components.solisconnect.config_flow import CONN_TYPE_BOTH
     from custom_components.solisconnect.const import CONN_TYPE_TCP, PROTO_BOTH_FAILOVER
 
+    async def fake_read_input_register(register, count):
+        if register == 33004:
+            return None  # no serial data; the Modbus serial stays "sn999" as typed
+        return [1]
+
     with (
         patch("custom_components.solisconnect.modbus_controller.ModbusController.connect", return_value=True),
-        patch("custom_components.solisconnect.modbus_controller.ModbusController.async_read_input_register", return_value=[1]),
+        patch(
+            "custom_components.solisconnect.modbus_controller.ModbusController.async_read_input_register",
+            side_effect=fake_read_input_register,
+        ),
         patch(
             "custom_components.solisconnect.cloud.api_client.SolisCloudApiClient.async_inverter_list",
             new=AsyncMock(return_value=[{"id": "1", "sn": "sn999", "productModel": "3102"}]),

tests/test_config_flow.py

@@ -8,6 +8,12 @@
 from custom_components.solisconnect.const import CONN_TYPE_TCP, DOMAIN
 
 
+def _encode_serial_registers(serial: str) -> list[int]:
+    """Inverse of helpers.extract_serial_number: pack an ASCII serial into 16-bit words."""
+    padded = serial if len(serial) % 2 == 0 else serial + "\x00"
+    return [(ord(padded[i]) << 8) | ord(padded[i + 1]) for i in range(0, len(padded), 2)]
+
+
 @pytest.fixture(autouse=True)
 def auto_enable_custom_integrations(enable_custom_integrations):
     yield
@@ -81,6 +87,8 @@ async def test_flow_user_hmi_version_overrides_has_v2(hass: HomeAssistant):
     async def fake_read_input_register(register, count):
         if register == 33002:
             return [0x4AFF]  # below the V2 threshold
+        if register == 33004:
+            return None  # no serial data available; must not corrupt the typed serial
         return [1]
 
     with (
@@ -113,6 +121,7 @@ async def fake_read_input_register(register, count):
 
         assert result["type"] == data_entry_flow.FlowResultType.CREATE_ENTRY
         assert result["data"]["has_v2"] is False
+        assert result["data"]["inverter_serial"] == "SN124"  # no serial detected; typed value survives
 
 
 @pytest.mark.asyncio
@@ -122,6 +131,8 @@ async def test_flow_user_hmi_read_failure_keeps_user_choice(hass: HomeAssistant)
     async def fake_read_input_register(register, count):
         if register == 33002:
             raise TimeoutError("no response")
+        if register == 33004:
+            return None
         return [1]
 
     with (
@@ -154,6 +165,92 @@ async def fake_read_input_register(register, count):
 
         assert result["type"] == data_entry_flow.FlowResultType.CREATE_ENTRY
         assert result["data"]["has_v2"] is False
+        assert result["data"]["inverter_serial"] == "SN125"
+
+
+@pytest.mark.asyncio
+async def test_flow_user_device_serial_overrides_typed_serial(hass: HomeAssistant):
+    """A serial read from device registers 33004-33019 overrides a mistyped form value."""
+    device_serial_registers = _encode_serial_registers("1234567890123456")
+
+    async def fake_read_input_register(register, count):
+        if register == 33004:
+            return device_serial_registers
+        return [1]
+
+    with (
+        patch("custom_components.solisconnect.modbus_controller.ModbusController.connect", return_value=True),
+        patch(
+            "custom_components.solisconnect.modbus_controller.ModbusController.async_read_input_register",
+            side_effect=fake_read_input_register,
+        ),
+        patch("custom_components.solisconnect.async_setup_entry", return_value=True),
+    ):
+        result = await hass.config_entries.flow.async_init(DOMAIN, context={"source": config_entries.SOURCE_USER})
+        result = await hass.config_entries.flow.async_configure(result["flow_id"], user_input={"connection_type": CONN_TYPE_TCP})
+
+        config_input = {
+            "host": "1.2.3.4",
+            "port": 502,
+            "slave": 1,
+            "model": "S6-EH1P",
+            "connection": "S2_WL_ST",
+            "has_v2": True,
+            "has_pv": True,
+            "has_ac_coupling": False,
+            "has_parallel": False,
+            "has_battery": True,
+            "has_hv_battery": False,
+            "has_generator": False,
+            "inverter_serial": "wrongserial",
+        }
+        result = await hass.config_entries.flow.async_configure(result["flow_id"], user_input=config_input)
+
+        assert result["type"] == data_entry_flow.FlowResultType.CREATE_ENTRY
+        assert result["data"]["inverter_serial"] == "1234567890123456"
+
+
+@pytest.mark.asyncio
+async def test_flow_user_grid_model_skips_serial_detection(hass: HomeAssistant):
+    """Grid/string inverters don't expose the serial-number register range; detection must be skipped."""
+    registers_read = []
+
+    async def fake_read_input_register(register, count):
+        registers_read.append(register)
+        return [1]
+
+    with (
+        patch("custom_components.solisconnect.modbus_controller.ModbusController.connect", return_value=True),
+        patch(
+            "custom_components.solisconnect.modbus_controller.ModbusController.async_read_input_register",
+            side_effect=fake_read_input_register,
+        ),
+        patch("custom_components.solisconnect.async_setup_entry", return_value=True),
+    ):
+        result = await hass.config_entries.flow.async_init(DOMAIN, context={"source": config_entries.SOURCE_USER})
+        result = await hass.config_entries.flow.async_configure(result["flow_id"], user_input={"connection_type": CONN_TYPE_TCP})
+
+        config_input = {
+            "host": "1.2.3.4",
+            "port": 502,
+            "slave": 1,
+            "model": "S6-GR1P",
+            "connection": "S2_WL_ST",
+            "has_v2": True,
+            "has_pv": True,
+            "has_ac_coupling": False,
+            "has_parallel": False,
+            "has_battery": True,
+            "has_hv_battery": False,
+            "has_generator": False,
+            "inverter_serial": "sn126",
+        }
+        result = await hass.config_entries.flow.async_configure(result["flow_id"], user_input=config_input)
+
+        assert result["type"] == data_entry_flow.FlowResultType.CREATE_ENTRY
+        assert result["data"]["inverter_serial"] == "SN126"
+        assert 33004 not in registers_read  # serial detection is hybrid-only; grid/string lacks this register range
+        assert 33002 in registers_read  # HMI-version detection is not gated by inverter type
 
 
 @pytest.mark.asyncio