diff --git a/homeassistant/components/solaredge/sensor.py b/homeassistant/components/solaredge/sensor.py
index 479362eb22d6..5a9913a31c65 100644
--- a/homeassistant/components/solaredge/sensor.py
+++ b/homeassistant/components/solaredge/sensor.py
@@ -543,7 +543,8 @@ class SolarEdgeEnergyDetailsSensor(SolarEdgeSensorEntity):
         """Initialize the power flow sensor."""
         super().__init__(sensor_type, data_service)
 
-        self._attr_native_unit_of_measurement = data_service.unit
+        if data_service.unit is not None:
+            self._attr_native_unit_of_measurement = data_service.unit
 
     @property
     @override
@@ -571,7 +572,8 @@ class SolarEdgePowerFlowSensor(SolarEdgeSensorEntity):
         """Initialize the power flow sensor."""
         super().__init__(description, data_service)
 
-        self._attr_native_unit_of_measurement = data_service.unit
+        if data_service.unit is not None:
+            self._attr_native_unit_of_measurement = data_service.unit
 
     @property
     @override
diff --git a/tests/components/solaredge/test_sensor.py b/tests/components/solaredge/test_sensor.py
index 72e9647eebd5..721c40fc6d41 100644
--- a/tests/components/solaredge/test_sensor.py
+++ b/tests/components/solaredge/test_sensor.py
@@ -213,6 +213,24 @@ async def test_energy_details_sensor_unknown_when_no_meters(
     assert state.state == STATE_UNKNOWN
 
 
+@pytest.mark.usefixtures("entity_registry_enabled_by_default")
+async def test_energy_details_sensor_keeps_unit_when_api_fails(
+    recorder_mock: Recorder,
+    hass: HomeAssistant,
+    mock_config_entry: MockConfigEntry,
+    solaredge_api: Mock,
+) -> None:
+    """Test energy detail sensors keep their unit when the initial API call fails."""
+    solaredge_api.get_energy_details.return_value = {}
+
+    await setup_integration(hass, mock_config_entry)
+
+    state = hass.states.get("sensor.solaredge_produced_energy")
+    assert state is not None
+    assert state.state == STATE_UNAVAILABLE
+    assert state.attributes["unit_of_measurement"] == "Wh"
+
+
 @pytest.mark.usefixtures("entity_registry_enabled_by_default")
 async def test_energy_details_filters_meters(
     recorder_mock: Recorder,