diff --git a/configurations/home-assistant/configuration.yaml b/configurations/home-assistant/configuration.yaml
index ae2a0c9..ca6ef14 100644
--- a/configurations/home-assistant/configuration.yaml
+++ b/configurations/home-assistant/configuration.yaml
@@ -11,3 +11,77 @@ http:
   use_x_forwarded_for: true
   trusted_proxies:
   - 172.16.0.0/12
+
+# ---- 1. Track a running monthly average of the EPEX day-ahead price ----
+# (Replace sensor.nordpool_kwh_be_eur_3_10_0 with your actual Nord Pool entity ID)
+sensor:
+  - platform: statistics
+    name: "Epex Monthly Average"
+    entity_id: sensor.nordpool_kwh_be_eur_3_10_0
+    state_characteristic: mean
+    max_age:
+      days: 31
+    sampling_size: 9999
+
+# ---- 2. Apply Mega's formula and add the fixed cost components ----
+template:
+  - sensor:
+      - name: "Mega Energy Price"
+        unique_id: mega_energy_price
+        unit_of_measurement: "€/kWh"
+        state: >
+          {% set epex = states('sensor.epex_monthly_average') | float(0) %}
+          {% set excl_vat = epex * 1.085 %}
+          {% set incl_vat = excl_vat * 1.06 %}
+          {{ incl_vat | round(5) }}
+
+      - name: "Mega All-in Price"
+        unique_id: mega_allin_price
+        unit_of_measurement: "€/kWh"
+        state: >
+          {% set energy = states('sensor.mega_energy_price') | float(0) %}
+          {% set green_power = 0.01554 %}
+          {% set distribution = 0.066985 %}
+          {% set excise = 0.0503288 %}
+          {% set energy_contribution = 0.0020417 %}
+          {{ (energy + green_power + distribution + excise + energy_contribution) | round(5) }}
+  - sensor:
+      - name: "Mega Injection Price"
+        unique_id: mega_injection_price
+        unit_of_measurement: "€/kWh"
+        state: >
+          {% set epex_spp = states('sensor.epex_spp_monthly_average') | float(0) %}
+          {% set price = (epex_spp * 0.96) - 1 %}
+          {{ [price, 0] | max | round(5) }}
+
+  - sensor:
+      - name: "Cistern Water Height"
+        unique_id: cistern_water_height
+        unit_of_measurement: "mm"
+        state_class: measurement
+        state: >
+          {% set sensor_offset = 290 %}   {# distance (mm) from sensor to tank bottom #}
+          {% set distance = states('sensor.regenput_sensor_distance') | float(0) %}
+          {% set height = sensor_offset - distance %}
+          {{ [ [height, 0] | max, sensor_offset] | min | round(1) }}
+
+      - name: "Cistern Volume"
+        unique_id: cistern_volume
+        unit_of_measurement: "L"
+        device_class: volume
+        state_class: measurement
+        state: >
+          {% set diameter = 1450 %}  {# mm #}
+          {% set radius = diameter / 2 %}
+          {% set height = states('sensor.cistern_water_height') | float(0) %}
+          {% set volume_mm3 = 3.14159265 * (radius ** 2) * height %}
+          {{ (volume_cm3 / 1000000) | round(1) }}   {# convert mm³ to liters #}
+
+      - name: "Cistern Fill Percentage"
+        unique_id: cistern_fill_percentage
+        unit_of_measurement: "%"
+        state_class: measurement
+        state: >
+          {% set sensor_offset = 290 %}  {# same as above, = full tank height #}
+          {% set height = states('sensor.cistern_water_height') | float(0) %}
+          {{ (height / sensor_offset * 100) | round(1) }}