This blueprints uses the nordpool integration and lets you choose howe many hours you will define as expesive, and make a sensor block temperature based on that information.

block_heat.yaml

blueprint:
  name: Block heat
  description: >
    This blueprints uses the nordpool integration and lets you choose howe
    many hours you will define as expesive, and make a sensor block temperature based on that information.

    In order for this blueprint to work, the following elements must be met.
      - Nordpool integration
      - An outdoor sensor that has the actual outdoor temperature
      - A sensor that can manipulate the outdoor temperature, for example https://www.ohmigo.io/product-page/ohmigo-ohm-on-wifi or equivalent
      
      Sometimes you have to wait an hour for the autonation to start, if nothing else, you can manually run it.
      
    **Version: 1.0**
   
  domain: automation
  input:
    grid_area:
      name: Grid Area Sensor
      description: This is your grid area sensor
      selector:
        entity:
          domain:
            - sensor
          integration: nordpool
          multiple: false
    expensive_hours:
      name: Expensive Hours
      description: Numbers of Expensive hours to block
      default: 4
      selector:
        number:
          min: 0
          max: 24
          mode: slider
          step: 1.0
    temperature_sensor:
      name: Temperature Sensor
      description: Here you select your real outside temperature sensor
      selector:
        entity:
          domain:
            - sensor
          device_class:
            - temperature
          multiple: false
    refresh_temperature_delay:
      name: Cheap Hours - Refresh Controllable Temperature Delay Time
      description:
        This will refresh the controllable temperature sensor to mirror the outside
        temperature sensor in the set time period.
      default: 5
      selector:
        number:
          min: 0.0
          max: 10
          step: 0.25
          unit_of_measurement: Minutes
    controll_sensor:
      name: Controllable Sensor
      description: Your controllable sensor *
      selector:
        entity:
          domain:
            - number
          integration: mqtt
          multiple: false
    virtual_temperature:
      name: Virtual Block Temp
      description: Your selected virtual temperature to block your heater
      default: 20
      selector:
        number:
          min: 0.0
          max: 30
          mode: slider
          step: 1.0
          unit_of_measurement: °C

# Variables
variables:
  grid_area: !input grid_area
  expensive_hours: !input expensive_hours
  temperature_sensor: !input temperature_sensor
  refresh_temperature_delay: !input refresh_temperature_delay
  controll_sensor: !input controll_sensor
  virtual_temperature: !input virtual_temperature

# Triggers
trigger:
  - platform: state
    entity_id: !input grid_area
  - platform: homeassistant
    event: start
  - platform: time_pattern
    seconds: 30

# Conditions
action:
  - choose:
      - conditions:
          - condition: template
            value_template: "{{ (state_attr(grid_area,'today')|sort)[24 - expensive_hours|int] < states(grid_area)|float }}" 
        sequence:
          - service: number.set_value
            entity_id: !input controll_sensor
            data:
              value: !input virtual_temperature
      - conditions:
          - condition: template
            value_template: "{{ (state_attr(grid_area,'today')|sort)[24 - expensive_hours|int] > states(grid_area)|float }}" 
        sequence:
          - alias: "Refresh the controllable temperature sensor"
            repeat:
              until: "{{ (state_attr(grid_area,'today')|sort)[24 - expensive_hours|int] < states(grid_area)|float }}" 
              sequence:
                - service: number.set_value
                  entity_id: !input controll_sensor
                  data:
                    value: "{{ states(temperature_sensor)|float(0) }}"
                - alias: "Refresh time before setting the controllable temperature again"
                  delay:
                    minutes: !input refresh_temperature_delay