Use hourly prices in Home Assistant

This guide shows how to bring the hourly grid fee into Home Assistant and use it to run an EV charger, heat pump or other device during the cheapest hours of the day. No add-ons are needed, only Home Assistant's built-in RESTful and Template integrations.

What you get

Entity	What it shows
sensor.grid_fee_prices	Fetches the prices once an hour. The prices are stored in its actual attribute.
sensor.grid_fee_price_now	The price for the current hour, in SEK/kW incl. VAT. Use it in dashboards and history graphs.
binary_sensor.grid_fee_cheap_hour	on during the 4 cheapest hours of the day. Use it to start and stop devices.

Plus an example automation that turns an EV charger on and off.

Configuration

Add this to your configuration.yaml, change the product and switch.ev_charger to match your setup, then check the configuration and restart Home Assistant:

configuration.yaml

# Göteborg Energi hourly grid fee in Home Assistant.
# Add to configuration.yaml, check the configuration and restart Home Assistant.

rest:
  - resource: https://api.uat.goteborgenergi.cloud/gridtariff/v0/prices?product=GN6KWST
    scan_interval: 3600 # fetch once an hour
    timeout: 30
    sensor:
      - name: Grid fee prices
        unique_id: goteborg_energi_grid_fee_prices
        # The state is the number of hours with set prices.
        # The prices themselves are stored in the "actual" attribute.
        value_template: "{{ value_json.actual | count }}"
        json_attributes:
          - actual

template:
  - sensor:
      - name: Grid fee price now
        unique_id: goteborg_energi_grid_fee_price_now
        unit_of_measurement: "SEK/kW"
        availability: "{{ state_attr('sensor.grid_fee_prices', 'actual') is not none }}"
        state: >
          {% set ns = namespace(price=none) %}
          {% for hour in state_attr('sensor.grid_fee_prices', 'actual') or [] %}
            {% if as_timestamp(hour.start) <= now().timestamp() < as_timestamp(hour.end) %}
              {% set ns.price = hour.priceIncVat %}
            {% endif %}
          {% endfor %}
          {{ ns.price }}

  - binary_sensor:
      # On during the cheapest hours of the day
      - name: Grid fee cheap hour
        unique_id: goteborg_energi_grid_fee_cheap_hour
        availability: "{{ state_attr('sensor.grid_fee_prices', 'actual') is not none }}"
        state: >
          {% set hours_needed = 4 %}
          {% set today = now().date() | string %}
          {% set ns = namespace(prices=[], now_price=none) %}
          {% for hour in state_attr('sensor.grid_fee_prices', 'actual') or [] %}
            {% if hour.start[:10] == today %}
              {% set ns.prices = ns.prices + [hour.priceIncVat] %}
            {% endif %}
            {% if as_timestamp(hour.start) <= now().timestamp() < as_timestamp(hour.end) %}
              {% set ns.now_price = hour.priceIncVat %}
            {% endif %}
          {% endfor %}
          {% if ns.now_price is none or not ns.prices %}
            false
          {% else %}
            {% set limit = (ns.prices | sort)[[hours_needed, ns.prices | count] | min - 1] %}
            {{ ns.now_price <= limit }}
          {% endif %}

automation:
  - alias: Charge the EV during cheap grid fee hours
    triggers:
      - trigger: state
        entity_id: binary_sensor.grid_fee_cheap_hour
        to: "on"
        id: cheap
      - trigger: state
        entity_id: binary_sensor.grid_fee_cheap_hour
        from: "on"
        id: not_cheap
    actions:
      - choose:
          - conditions:
              - condition: trigger
                id: cheap
            sequence:
              - action: switch.turn_on
                target:
                  entity_id: switch.ev_charger # replace with your charger
        default:
          - action: switch.turn_off
            target:
              entity_id: switch.ev_charger

If you already have rest:, template: or automation: sections, add the entries to them instead of creating new ones. You can also create the automation in the Home Assistant UI instead.

Adjusting it

• Number of hours: change hours_needed in the binary sensor. If several hours have the same price, more hours than that can be marked as cheap.
• Your tariff: replace GN6KWST in the URL with the product of your tariff. Only tariffs with an hourly power fee have hourly prices.
• When prices update: the next day's prices are set by 15:00. Fetching once an hour picks them up in time.

note

The binary sensor picks the cheapest hours among today's hours. If you want to plan across midnight, for example to charge the car overnight, compare the hours from now until the time it needs to be ready instead.