Home Assistant Czech Energy Spot Prices

Home Assistant integration that provides current Czech electricity spot prices based on OTE.

You can select an energy unit between kWh and MWh when configuring the integration. OTE prices are in EUR, but you can also select to use CZK (Czech Koruna) as a currency for displayed prices (based on ČNB rate for given day).

Important note

OTE (Czech market operator) uses hourly prices indexed from 1, so 1 (first hour of a day) means 0:00 - 1:00. It does NOT mean 1:00 - 2:00 as one might expect. Please keep this in mind when comparing prices reported by this integration with other sources (OTE, your electricity provider/distributor).

Installation

1. Copy custom_components/cz_energy_spot_prices directory into your custom_components in your configuration directory.
2. Restart Home Assistant
3. Open Settings -> Devices & Services -> Integration
4. Search for "Czech Energy Spot Prices" and click the search result
5. Configure Currency and Unit of energy
6. Submit

Sensors

Common attributes

At

timestamp when the cheapest hour starts

Hour

hour with the cheapest electricity (2 means that cheapest electricity is from 2:00 till 3:00 in timezone you've configured in Home Assistant)

Start

timestamp when consecutive block of cheapest hours starts, only available when the block is in the future

Start hour

hour when consecutive block of cheapest hours starts, only available when the block is in the future

End

timestamp when consecutive block of cheapest hours ends, only available when the block is in the future

End hour

hour when consecutive block of cheapest hours ends, only available when the block is in the future

Min

minimal price in the block, only available when the block is in the future

Max

maximal price in the block, only available when the block is in the future

Mean

average (mean) price in the block, only available when the block is in the future

Displaying a chart

If you want you display a chart with current day (or two days if it's after noon), you can install apexcharts-card card for Home Assistant and then use following config for it:

type: custom:apexcharts-card
header:
  show: true
  show_states: true
  colorize_states: true
graph_span: 2d
span:
  start: day
now:
  show: true
  label: Now
series:
  - entity: sensor.current_spot_electricity_price
    float_precision: 2
    type: column # or "line" if you prefer
    show:
      in_header: raw
    data_generator: |
      return Object.entries(entity.attributes).map(([date, value], index) => {
        return [new Date(date).getTime(), value];
      });

Find cheapest hours in selected interval

Add this as a template sensor. Change the intervals on lines 3-5, the sensor will be on when cheapest hour in any of the intervals is active. Or you can replace the last line with {{ min.cheapest_hours }} to display the cheapest hours.

This is useful for example if you want to turn on your water heater in the afternoon and then again during the night.

{# Define your intervals here as tuples (hour starting the interval, hour ending the interval (excluded)) #}
{% set intervals = [
  (0, 8),
  (8, 16),
  (16, 24),
] %}

{# We need to use namespace so we can write into it in inner cycle #}
{% set min = namespace(price=None, dt=None, cheapest_hours=[]) %}
{% set cheapest_hours = [] %}

{% for interval in intervals %}
  {# Reset min price from previous runs #}
  {% set min.price = None %}

  {# Go through all the hours in the interval (end excluded) and find the hour with lowest price #}
  {% for i in range(interval[0], interval[1]) %}
     {# Get datetime of current hour in current interval #}
     {% set hour_dt = now().replace(hour=i, minute=0, second=0, microsecond=0) %}

     {# Get value for that hour #}
     {% set value = states.sensor.current_spot_electricity_hour_order.attributes.get(hour_dt.isoformat()) %}

     {# Skip if not found #}
     {% if value is not defined %}
       {% break %}
     {% endif %}

     {# value is tuple (order, price), we'll use the price #}
     {% set price = value[1] %}

     {# Min price is not set or is higher than price of current hour => store the min price and hour #}
     {% if min.price is none or price < min.price %}
        {% set min.price = price %}
        {% set min.dt = hour_dt %}
     {% endif %}
  {% endfor %}

  {# Store cheapest hour in current interval #}
  {% set min.cheapest_hours = min.cheapest_hours + [min.dt.hour] %}
{% endfor %}

{# use this to get the cheapest hours #}
{# {{ min.cheapest_hours }} #}

{# return True if current hour is in the cheapest hour of any interval #}
{{ now().hour in min.cheapest_hours }}

Example automation for X cheapest hours

alias: Turn on for cheapest X hours
trigger:
  - platform: state
    entity_id:
      - sensor.current_spot_electricity_hour_order
condition: []
action:
  - if:
      - condition: numeric_state
        entity_id: sensor.current_spot_electricity_hour_order
        below: X # Replace with amount of hours you want to have it on
    then:
      - type: turn_on
        entity_id: # Add entity you want to turn on
    else:
      - type: turn_off
        entity_id: # Turn off the entity when cheapest interval ends
    enabled: true
mode: single

License

This integration is under Apache 2.0 License, the same license as Home Assistant itself.