diff --git a/homeassistant/components/mill/climate.py b/homeassistant/components/mill/climate.py
index 54791eac92f..e4ffbcba23e 100644
--- a/homeassistant/components/mill/climate.py
+++ b/homeassistant/components/mill/climate.py
@@ -24,7 +24,10 @@ from homeassistant.const import (
 from homeassistant.core import HomeAssistant, ServiceCall, callback
 from homeassistant.helpers import config_validation as cv
 from homeassistant.helpers.device_registry import CONNECTION_NETWORK_MAC, DeviceInfo
-from homeassistant.helpers.entity_platform import AddEntitiesCallback
+from homeassistant.helpers.entity_platform import (
+    AddEntitiesCallback,
+    async_get_current_platform,
+)
 from homeassistant.helpers.update_coordinator import CoordinatorEntity
 
 from .const import (
@@ -53,12 +56,6 @@ SET_ROOM_TEMP_SCHEMA = vol.Schema(
         vol.Optional(ATTR_SLEEP_TEMP): cv.positive_int,
     }
 )
-LIMIT_HEATING_POWER_SCHEMA = vol.Schema(
-    {
-        vol.Required(ATTR_ENTITY_ID): cv.entity_id,
-        vol.Required(ATTR_MAX_HEATING_POWER): vol.Range(min=0, max=2000),
-    }
-)
 
 
 async def async_setup_entry(
@@ -93,23 +90,19 @@ async def async_setup_entry(
         DOMAIN, SERVICE_SET_ROOM_TEMP, set_room_temp, schema=SET_ROOM_TEMP_SCHEMA
     )
 
-    async def max_heating_power(service: ServiceCall) -> None:
+    async def max_heating_power(entity: MillHeater, service: ServiceCall) -> None:
         """Limit heating power."""
-        entity_id = service.data.get(ATTR_ENTITY_ID)
-        heating_power = service.data.get(ATTR_MAX_HEATING_POWER)
-        for entity in entities:
-            if entity.entity_id == entity_id:
-                await mill_data_coordinator.mill_data_connection.max_heating_power(
-                    entity.heater_id, heating_power
-                )
-                return
-        raise ValueError(f"Entity id {entity_id} not found")
+        await mill_data_coordinator.mill_data_connection.max_heating_power(
+            entity.heater_id, service.data[ATTR_MAX_HEATING_POWER]
+        )
 
-    hass.services.async_register(
-        DOMAIN,
+    async_get_current_platform().async_register_entity_service(
         SERVICE_MAX_HEATING_POWER,
-        max_heating_power,
-        schema=LIMIT_HEATING_POWER_SCHEMA,
+        schema={
+            vol.Required(ATTR_ENTITY_ID): cv.entity_id,
+            vol.Required(ATTR_MAX_HEATING_POWER): vol.Range(min=0, max=2000),
+        },
+        func=max_heating_power,
     )
 
 
diff --git a/homeassistant/components/mill/coordinator.py b/homeassistant/components/mill/coordinator.py
index a83d28fc031..f5e2b1ba6dd 100644
--- a/homeassistant/components/mill/coordinator.py
+++ b/homeassistant/components/mill/coordinator.py
@@ -72,6 +72,7 @@ class MillDataUpdateCoordinator(DataUpdateCoordinator):
                 hourly_data = (
                     await self.mill_data_connection.fetch_historic_energy_usage(dev_id)
                 )
+                hourly_data = dict(sorted(hourly_data.items(), key=lambda x: x[0]))
                 _sum = 0.0
                 last_stats_time = None
             else:
@@ -84,15 +85,18 @@ class MillDataUpdateCoordinator(DataUpdateCoordinator):
                                 last_stats[statistic_id][0]["start"]
                             )
                         ).days
-                        + 1,
+                        + 2,
                     )
                 )
                 if not hourly_data:
                     return
+                hourly_data = dict(sorted(hourly_data.items(), key=lambda x: x[0]))
+                start_time = next(iter(hourly_data))
+
                 stats = await get_instance(self.hass).async_add_executor_job(
                     statistics_during_period,
                     self.hass,
-                    next(iter(hourly_data)),
+                    start_time,
                     None,
                     {statistic_id},
                     "hour",
diff --git a/homeassistant/components/mill/manifest.json b/homeassistant/components/mill/manifest.json
index 05ec456162d..8dd1424e2ba 100644
--- a/homeassistant/components/mill/manifest.json
+++ b/homeassistant/components/mill/manifest.json
@@ -7,5 +7,5 @@
   "documentation": "https://www.home-assistant.io/integrations/mill",
   "iot_class": "local_polling",
   "loggers": ["mill", "mill_local"],
-  "requirements": ["millheater==0.12.0", "mill-local==0.3.0"]
+  "requirements": ["millheater==0.12.1", "mill-local==0.3.0"]
 }
diff --git a/requirements_all.txt b/requirements_all.txt
index 671cd6b1f78..806b1604d10 100644
--- a/requirements_all.txt
+++ b/requirements_all.txt
@@ -1373,7 +1373,7 @@ microBeesPy==0.3.2
 mill-local==0.3.0
 
 # homeassistant.components.mill
-millheater==0.12.0
+millheater==0.12.1
 
 # homeassistant.components.minio
 minio==7.1.12
diff --git a/requirements_test_all.txt b/requirements_test_all.txt
index 10ed0c5618a..d67da8efe6b 100644
--- a/requirements_test_all.txt
+++ b/requirements_test_all.txt
@@ -1142,7 +1142,7 @@ microBeesPy==0.3.2
 mill-local==0.3.0
 
 # homeassistant.components.mill
-millheater==0.12.0
+millheater==0.12.1
 
 # homeassistant.components.minio
 minio==7.1.12