diff --git a/homeassistant/components/sofar/diagnostics.py b/homeassistant/components/sofar/diagnostics.py
new file mode 100644
index 000000000000..8a4b2044aacf
--- /dev/null
+++ b/homeassistant/components/sofar/diagnostics.py
@@ -0,0 +1,35 @@
+"""Diagnostics support for Sofar."""
+
+from typing import Any
+
+from homeassistant.components.diagnostics import async_redact_data
+from homeassistant.core import HomeAssistant
+
+from .coordinator import SofarConfigEntry
+
+TO_REDACT = {"serial_number"}
+
+_SERIAL_NUMBER_REGISTERS = range(0x0445, 0x044C)
+
+
+async def async_get_config_entry_diagnostics(
+    hass: HomeAssistant, entry: SofarConfigEntry
+) -> dict[str, Any]:
+    """Return diagnostics for a config entry."""
+    device = entry.runtime_data.readings.device
+    raw = await device.async_read_raw()
+    if (holding := raw.get("holding")) is not None:
+        for address in _SERIAL_NUMBER_REGISTERS:
+            holding.pop(address, None)
+
+    return async_redact_data(
+        {
+            "model": device.model,
+            "inverter_type": device.inverter_type,
+            "serial_number": device.serial_number,
+            "readings_components": device.readings_components,
+            "settings_components": device.settings_components,
+            "raw": raw,
+        },
+        TO_REDACT,
+    )
diff --git a/homeassistant/components/sofar/quality_scale.yaml b/homeassistant/components/sofar/quality_scale.yaml
index dc2bd37d87bd..004c68be592e 100644
--- a/homeassistant/components/sofar/quality_scale.yaml
+++ b/homeassistant/components/sofar/quality_scale.yaml
@@ -49,7 +49,7 @@ rules:
 
   # Gold
   devices: done
-  diagnostics: todo
+  diagnostics: done
   discovery-update-info:
     status: exempt
     comment: Modbus TCP gateways have no discovery protocol to update network info from.
diff --git a/tests/components/sofar/snapshots/test_diagnostics.ambr b/tests/components/sofar/snapshots/test_diagnostics.ambr
new file mode 100644
index 000000000000..e8c1ff9856b1
--- /dev/null
+++ b/tests/components/sofar/snapshots/test_diagnostics.ambr
@@ -0,0 +1,151 @@
+# serializer version: 1
+# name: test_diagnostics
+  dict({
+    'inverter_type': 1537,
+    'model': '4.4 KTLX-G3',
+    'raw': dict({
+      'holding': dict({
+        '1028': 2,
+        '1029': 0,
+        '1030': 0,
+        '1031': 0,
+        '1032': 0,
+        '1033': 0,
+        '1034': 0,
+        '1035': 0,
+        '1036': 0,
+        '1037': 0,
+        '1038': 0,
+        '1039': 0,
+        '1040': 0,
+        '1041': 0,
+        '1042': 0,
+        '1043': 0,
+        '1044': 0,
+        '1045': 0,
+        '1046': 0,
+        '1047': 0,
+        '1048': 0,
+        '1049': 0,
+        '1050': 0,
+        '1051': 0,
+        '1052': 0,
+        '1053': 0,
+        '1054': 0,
+        '1055': 0,
+        '1056': 0,
+        '1057': 0,
+        '1068': 0,
+        '1069': 0,
+        '1070': 0,
+        '1071': 0,
+        '1072': 0,
+        '1073': 0,
+        '1100': 0,
+        '1101': 22065,
+        '1102': 12336,
+        '1103': 22066,
+        '1104': 12848,
+        '1105': 0,
+        '1106': 0,
+        '1156': 5000,
+        '1157': 0,
+        '1158': 0,
+        '1159': 0,
+        '1160': 0,
+        '1161': 0,
+        '1162': 0,
+        '1163': 0,
+        '1164': 0,
+        '1165': 0,
+        '1166': 0,
+        '1167': 0,
+        '1168': 0,
+        '1169': 0,
+        '1170': 0,
+        '1171': 0,
+        '1172': 0,
+        '1173': 0,
+        '1174': 0,
+        '1175': 0,
+        '1176': 0,
+        '1177': 0,
+        '1178': 0,
+        '1179': 0,
+        '1180': 0,
+        '1181': 0,
+        '1182': 0,
+        '1183': 0,
+        '1184': 0,
+        '1185': 0,
+        '1186': 0,
+        '1187': 0,
+        '1188': 0,
+        '1189': 0,
+        '1190': 0,
+        '1191': 0,
+        '1192': 0,
+        '1193': 0,
+        '1194': 0,
+        '1195': 0,
+        '1196': 0,
+        '1197': 0,
+        '1198': 0,
+        '1199': 0,
+        '1200': 0,
+        '1201': 0,
+        '1202': 0,
+        '1203': 0,
+        '1204': 0,
+        '1205': 0,
+        '1206': 0,
+        '1207': 0,
+        '1208': 0,
+        '1209': 0,
+        '1210': 0,
+        '1211': 0,
+        '1212': 0,
+        '1412': 0,
+        '1413': 0,
+        '1414': 250,
+        '1415': 0,
+        '1416': 0,
+        '1417': 180,
+        '1476': 43,
+        '1668': 0,
+        '1669': 1000,
+        '1670': 0,
+        '1671': 150,
+        '1672': 0,
+        '1673': 0,
+        '1674': 0,
+        '1675': 0,
+        '1676': 0,
+        '1677': 0,
+        '1678': 0,
+        '1679': 0,
+        '1680': 0,
+        '1681': 0,
+        '1682': 0,
+        '1683': 0,
+        '4131': 0,
+        '4132': 0,
+        '4356': 0,
+        '4357': 0,
+        '4358': 0,
+      }),
+    }),
+    'readings_components': list([
+      'state',
+      'grid',
+      'pv_1_2',
+      'energy',
+    ]),
+    'serial_number': '**REDACTED**',
+    'settings_components': list([
+      'feed_in',
+      'remote',
+      'active_power_control',
+    ]),
+  })
+# ---
diff --git a/tests/components/sofar/test_diagnostics.py b/tests/components/sofar/test_diagnostics.py
new file mode 100644
index 000000000000..cd2a4f2e71ea
--- /dev/null
+++ b/tests/components/sofar/test_diagnostics.py
@@ -0,0 +1,35 @@
+"""Test the Sofar Inverter Modbus diagnostics."""
+
+from syrupy.assertion import SnapshotAssertion
+
+from homeassistant.core import HomeAssistant
+
+from tests.common import MockConfigEntry
+from tests.components.diagnostics import get_diagnostics_for_config_entry
+from tests.typing import ClientSessionGenerator
+
+
+async def test_diagnostics(
+    hass: HomeAssistant,
+    hass_client: ClientSessionGenerator,
+    init_integration: MockConfigEntry,
+    snapshot: SnapshotAssertion,
+) -> None:
+    """Test generating diagnostics for a config entry."""
+    diag = await get_diagnostics_for_config_entry(hass, hass_client, init_integration)
+
+    assert diag == snapshot
+
+
+async def test_diagnostics_redacts_serial_number(
+    hass: HomeAssistant,
+    hass_client: ClientSessionGenerator,
+    init_integration: MockConfigEntry,
+) -> None:
+    """Test the serial number is redacted, both as a field and as raw ASCII."""
+    diag = await get_diagnostics_for_config_entry(hass, hass_client, init_integration)
+
+    assert diag["serial_number"] == "**REDACTED**"
+    holding = diag["raw"]["holding"]
+    for address in range(0x0445, 0x044C):
+        assert str(address) not in holding