diff --git a/homeassistant/components/osoenergy/sensor.py b/homeassistant/components/osoenergy/sensor.py
index 18859627952..c2b1e75cd70 100644
--- a/homeassistant/components/osoenergy/sensor.py
+++ b/homeassistant/components/osoenergy/sensor.py
@@ -55,7 +55,7 @@ SENSOR_TYPES: dict[str, OSOEnergySensorEntityDescription] = {
         key="optimization_mode",
         translation_key="optimization_mode",
         device_class=SensorDeviceClass.ENUM,
-        options=["off", "oso", "gridcompany", "smartcompany", "advanced"],
+        options=["off", "oso", "gridcompany", "smartcompany", "advanced", "nettleie"],
         value_fn=lambda entity_data: entity_data.state.lower(),
     ),
     "power_load": OSOEnergySensorEntityDescription(
diff --git a/homeassistant/components/osoenergy/strings.json b/homeassistant/components/osoenergy/strings.json
index b463c1d4d3f..4b48f084fb7 100644
--- a/homeassistant/components/osoenergy/strings.json
+++ b/homeassistant/components/osoenergy/strings.json
@@ -58,6 +58,7 @@
         "state": {
           "advanced": "Advanced",
           "gridcompany": "Grid company",
+          "nettleie": "Nettleie",
           "off": "[%key:common::state::off%]",
           "oso": "OSO",
           "smartcompany": "Smart company"