Add missing device class to SAJ energy sensors (#54048)

homeassistant/components/saj/sensor.py

@@ -18,6 +18,7 @@ from homeassistant.const import (
     CONF_PASSWORD,
     CONF_TYPE,
     CONF_USERNAME,
+    DEVICE_CLASS_ENERGY,
     DEVICE_CLASS_POWER,
     DEVICE_CLASS_TEMPERATURE,
     ENERGY_KILO_WATT_HOUR,
@@ -204,6 +205,8 @@ class SAJsensor(SensorEntity):
         """Return the device class the sensor belongs to."""
         if self.unit_of_measurement == POWER_WATT:
             return DEVICE_CLASS_POWER
+        if self.unit_of_measurement == ENERGY_KILO_WATT_HOUR:
+            return DEVICE_CLASS_ENERGY
         if (
             self.unit_of_measurement == TEMP_CELSIUS
             or self._sensor.unit == TEMP_FAHRENHEIT