Use electricity price and CO2 in openHAB without building a custom add-on

Core logic explained early

The price logic is not “forecast only”. It deliberately works in two steps so that official market data wins whenever it exists.

Recommended entry point: summary

There is a dedicated summary path for openHAB. Technically it returns the same compact automation summary as the other integrations, but with a structure that fits directly into HTTP Binding, JSONPATH and rules.

Alternative for your own price logic: openhab/prices

For more advanced setups there is now also a second openHAB path that returns only the price series. It is intended for your own rules, JS scripting, charts or external preprocessing.

What the API actually returns

The openHAB summary path does not return a special openHAB-only structure. It returns a compact automation summary instead. That is exactly the benefit: the same core information stays readable and testable outside openHAB as well.

If you need a real price series for your own calculations instead of the compact summary, use /api/v1/openhab/prices. The summary intentionally stays compact. The price-series path is meant for advanced openHAB logic.

Price series for your own rules: openhab/prices

The extra price-series path deliberately returns prices only, without CO2 fields and without precomputed window logic. That is the point: you decide yourself how to evaluate the slots or combine them with house state, PV, battery or your own thresholds.

https://api.energypriceforecast.eu/api/v1/openhab/prices?country=de&hours=48&mode=mixed&resolution=15m

https://api.energypriceforecast.eu/api/v1/openhab/prices?country=de&hours=48&mode=mixed&resolution=15m&price_mode=retail&plz=10115

Important: in 15m mode, forecast values are not smoothed between hours. The API does not invent intermediate prices. Instead, each forecast hour is simply repeated across four quarter-hour slots.

Base price or total retail price?

The openHAB summary path still deliberately returns base or market prices. The prices path also returns base prices by default, but can optionally return assumption-based retail totals.

Horizon and resolution

The examples use hours=48 and window_hours=4. That is only a starting value, not the full technical ceiling.

Important: source.price.day_ahead_entries and source.price.forecast_entries count slots, not hours. If day-ahead arrives in quarter-hour slots, values such as 97 or 132 can be perfectly plausible. A forecast_entries value of 0 is also possible when the requested horizon is already fully covered by published day-ahead slots.

Quick start for copy-paste

1. Install the HTTP Binding and JSONPATH in openHAB.
2. Create a file named strompreisvorhersage.things and paste in the Thing block below.
3. Create a file named strompreisvorhersage.items and paste in the Item block below.
4. Save the files and reload openHAB. After that, the Items should have values.

Thing file for openHAB

This variant runs without an API key and refreshes the data every 15 minutes.

Thing http:url:strompreisvorhersage "StrompreisVorhersage" [
  baseURL="https://api.energypriceforecast.eu/api/v1/openhab/summary?country=de&hours=48&window_hours=4",
  refresh=900
] {
  Channels:
    Type number : currentPrice "Current price" [ stateTransformation="JSONPATH($.flat.current_price)" ]
    Type number : currentCo2 "Current CO2 intensity" [ stateTransformation="JSONPATH($.flat.current_co2_g_kwh)" ]
    Type string : cheapestWindowStart "Cheapest window start" [ stateTransformation="JSONPATH($.flat.cheapest_window_start)" ]
    Type string : greenestWindowStart "Greenest window start" [ stateTransformation="JSONPATH($.flat.greenest_window_start)" ]
    Type string : isCheapestWindowNow "Best price window active now" [ stateTransformation="JSONPATH($.flat.is_cheapest_window_now)" ]
    Type number : cheapestWindowRemainingMinutes "Best price window remaining minutes" [ stateTransformation="JSONPATH($.flat.cheapest_window_remaining_minutes)" ]
    Type string : nextFullCheapestWindowStart "Next full price window" [ stateTransformation="JSONPATH($.price.next_full_window.start)" ]
}

If you want another market, usually only the country parameter in the URL changes.

Optional with your own API key

For higher limits or later product tiers, you can add a Bearer token to the same request. In openHAB, that can be done directly via the header of the HTTP Thing.

Thing http:url:strompreisvorhersage "StrompreisVorhersage" [
  baseURL="https://api.energypriceforecast.eu/api/v1/openhab/summary?country=de&hours=72&window_hours=4",
  refresh=900,
  headers="Authorization=Bearer YOUR_API_KEY"
] {
  Channels:
    Type number : currentPrice "Current price" [ stateTransformation="JSONPATH($.flat.current_price)" ]
    Type number : currentCo2 "Current CO2 intensity" [ stateTransformation="JSONPATH($.flat.current_co2_g_kwh)" ]
    Type string : apiKeyState "API key state" [ stateTransformation="JSONPATH($.meta.api_key_state)" ]
    Type number : allowedHorizon "Allowed horizon" [ stateTransformation="JSONPATH($.meta.allowed_horizon_hours)" ]
    Type number : usedCallsToday "Used calls today" [ stateTransformation="JSONPATH($.meta.used_calls_today)" ]
}

If you do not have your own key, simply leave out the header. Basic usage still works without a key.

Item file for openHAB

These Items bind the most important channels directly.

Number Strompreis_Aktuell "Current price [%.4f EUR/kWh]" { channel="http:url:strompreisvorhersage:currentPrice" }
Number Strompreis_CO2 "Current CO2 intensity [%.1f gCO2/kWh]" { channel="http:url:strompreisvorhersage:currentCo2" }
String Strompreis_Guenstigstes_Fenster_Start "Cheapest window start [%s]" { channel="http:url:strompreisvorhersage:cheapestWindowStart" }
String Strompreis_Gruenstes_Fenster_Start "Greenest window start [%s]" { channel="http:url:strompreisvorhersage:greenestWindowStart" }
String Strompreis_Bestes_Fenster_Jetzt "Best price window active now [%s]" { channel="http:url:strompreisvorhersage:isCheapestWindowNow" }
Number Strompreis_Bestes_Fenster_Restminuten "Best price window remaining [%.0f min]" { channel="http:url:strompreisvorhersage:cheapestWindowRemainingMinutes" }
String Strompreis_Naechstes_Vollfenster_Start "Next full price window [%s]" { channel="http:url:strompreisvorhersage:nextFullCheapestWindowStart" }

If you also use the meta channels from the API-key example, you can add matching Number or String Items for them as well.

For automations: do not wait only for future start times

For display purposes, cheapest_window_start can be enough. For automations, however, it is usually more important to know whether the mathematically best window is already active. That is exactly what flat.is_cheapest_window_now is for. If that value is true, you do not need to trigger on a future start time.

rule "Allow load in best price window"
when
  Time cron "0 */5 * * * ?"
then
  if (Strompreis_Bestes_Fenster_Jetzt.state.toString == "true") {
    // turn device on or set release flag
  }
end

Pragmatic rule: price.next_full_window.start is good for planning. flat.is_cheapest_window_now is better for the actual runtime decision.

Meta fields worth knowing

Caching and error cases