Use electricity price and CO2 in ioBroker without building a custom adapter

Core logic explained early

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

Recommended endpoint

ioBroker has its own summary path. It returns the compact fields that are usually enough for first automations, plus meta fields for limits and API key status.

Alternative for custom price logic

If you do not want to work with the compact summary, there is also a second ioBroker path that returns only the price series. That path is meant for more advanced users who want to build their own window logic, charts, or pricing rules in JavaScript.

What the API actually returns

The endpoint returns a general automation summary. That is useful for ioBroker because you are not locked into one special adapter and can reuse the same data in scripts, dashboards or custom logic.

If you need a real price series for your own calculations instead of the compact summary, use the separate /api/v1/iobroker/prices path. The summary intentionally stays on compact base-price data. The price-series path also returns base prices by default, but can now optionally return assumption-based retail totals.

Price series for your own scripts: iobroker/prices

The extra price-series path intentionally returns prices only, without CO2 fields and without precomputed window logic. That is exactly the point: you can decide inside ioBroker how you want to compute cheap windows, thresholds, or visualizations.

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

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

Important: in 15m mode, forecast values are not smoothed between two hours. The API does not invent intermediate prices. Instead, it clearly marks that these quarter-hour slots come from one hourly forecast block.

Base price or total retail price?

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

Time horizon and resolution

The example uses hours=48 and window_hours=4. That is a sensible starting point, but not the only possible setup.

Important: source.price.day_ahead_entries and source.price.forecast_entries count slots, not hours. That is why values such as 97 day-ahead and 0 forecast can be perfectly valid.

Quick start for copy and paste

1. Open the JavaScript adapter in ioBroker Admin.
2. Create a new JavaScript script.
3. Paste the complete block below and save it.
4. Run it once manually or wait briefly. New states should appear under 0_userdata.0.energypriceforecast.

Ready-to-use script for the JavaScript adapter

The script fetches data immediately at startup and then every 30 minutes by default. That is a sensible default for many setups: day-ahead data does not change constantly, but the current slot, active windows and forecast context still move forward. If you do not have an API key, just leave API_KEY empty.

const axios = require("axios");

const COUNTRY = "de";
const API_KEY = "";
const API_URL = "https://api.energypriceforecast.eu/api/v1/iobroker/summary?country=" + COUNTRY + "&hours=48&window_hours=4";
const ROOT = "0_userdata.0.energypriceforecast";
const POLL_MS = 30 * 60 * 1000;

const STATE_DEFINITIONS = [
  [".current_price", 0, { name: "Current price", type: "number", role: "value", unit: "EUR/kWh", read: true, write: false }],
  [".current_co2_g_kwh", 0, { name: "Current CO2 intensity", type: "number", role: "value", unit: "gCO2/kWh", read: true, write: false }],
  [".cheapest_window_start", "", { name: "Cheapest window start", type: "string", role: "text", read: true, write: false }],
  [".greenest_window_start", "", { name: "Greenest window start", type: "string", role: "text", read: true, write: false }],
  [".is_cheapest_window_now", false, { name: "Best price window active now", type: "boolean", role: "indicator", read: true, write: false }],
  [".cheapest_window_remaining_minutes", 0, { name: "Best price window remaining minutes", type: "number", role: "value.interval", unit: "min", read: true, write: false }],
  [".next_full_cheapest_window_start", "", { name: "Next full price window", type: "string", role: "text", read: true, write: false }],
  [".is_greenest_window_now", false, { name: "Best CO2 window active now", type: "boolean", role: "indicator", read: true, write: false }],
  [".api_key_state", "missing", { name: "API key state", type: "string", role: "text", read: true, write: false }],
  [".allowed_horizon_hours", 0, { name: "Allowed horizon", type: "number", role: "value", unit: "h", read: true, write: false }],
  [".used_horizon_hours", 0, { name: "Used horizon", type: "number", role: "value", unit: "h", read: true, write: false }],
  [".rate_limit_daily", 0, { name: "Daily limit", type: "number", role: "value", read: true, write: false }],
  [".used_calls_today", 0, { name: "Used calls today", type: "number", role: "value", read: true, write: false }],
  [".last_update", "", { name: "Last update", type: "string", role: "text", read: true, write: false }],
  [".last_error", "", { name: "Last error", type: "string", role: "text", read: true, write: false }]
];

STATE_DEFINITIONS.forEach(([suffix, initialValue, definition]) => {
  createState(ROOT + suffix, initialValue, definition);
});

function setTextState(suffix, value) {
  setState(ROOT + suffix, value == null ? "" : String(value), true);
}

function setNumberState(suffix, value, digits) {
  if (!Number.isFinite(value)) {
    return;
  }

  const normalized = typeof digits === "number" ? Number(value.toFixed(digits)) : Number(value);
  setState(ROOT + suffix, normalized, true);
}

function setBooleanState(suffix, value) {
  if (typeof value !== "boolean") {
    return;
  }

  setState(ROOT + suffix, value, true);
}

async function updateEnergyPriceForecast() {
  const headers = {};

  if (API_KEY.trim()) {
    headers.Authorization = "Bearer " + API_KEY.trim();
  }

  try {
    const response = await axios.get(API_URL, {
      timeout: 10000,
      headers
    });

    const data = response.data || {};
    const flat = data.flat || {};
    const meta = data.meta || {};

    setNumberState(".current_price", flat.current_price, 4);
    setNumberState(".current_co2_g_kwh", flat.current_co2_g_kwh, 1);
    setTextState(".cheapest_window_start", flat.cheapest_window_start);
    setTextState(".greenest_window_start", flat.greenest_window_start);
    setBooleanState(".is_cheapest_window_now", flat.is_cheapest_window_now);
    setNumberState(".cheapest_window_remaining_minutes", flat.cheapest_window_remaining_minutes);
    setTextState(".next_full_cheapest_window_start", data.price && data.price.next_full_window ? data.price.next_full_window.start : null);
    setBooleanState(".is_greenest_window_now", flat.is_greenest_window_now);
    setTextState(".api_key_state", meta.api_key_state || (API_KEY.trim() ? "unknown" : "missing"));
    setNumberState(".allowed_horizon_hours", meta.allowed_horizon_hours);
    setNumberState(".used_horizon_hours", meta.used_horizon_hours);
    setNumberState(".rate_limit_daily", meta.rate_limit_daily);
    setNumberState(".used_calls_today", meta.used_calls_today);
    setTextState(".last_update", data.generated_at);
    setTextState(".last_error", "");
  } catch (error) {
    const statusCode = error && error.response ? error.response.status : null;
    const errorData = error && error.response ? error.response.data || {} : {};
    const errorMeta = errorData.meta || {};

    setTextState(".api_key_state", errorMeta.api_key_state || (API_KEY.trim() ? "error" : "missing"));

    if (statusCode === 401) {
      setTextState(".last_error", "401: API key missing, invalid, or disabled.");
    } else if (statusCode === 403) {
      setTextState(".last_error", "403: Access is not allowed for this route, market, or contract state.");
    } else if (statusCode === 429) {
      setTextState(".last_error", "429: Daily limit reached.");
    } else {
      setTextState(".last_error", "Request failed.");
    }

    console.error("EnergyPriceForecast error:", statusCode, error && error.message ? error.message : error);
  }
}

updateEnergyPriceForecast();
setInterval(updateEnergyPriceForecast, POLL_MS);

If you want another market, normally only COUNTRY changes. For Denmark, always use dk1 or dk2. If you intentionally want more frequent polling, change POLL_MS yourself. The default is deliberately conservative.

Where to put the API key

The key goes directly into the API_KEY variable. If you have received a test key, you can also raise the requested horizon in the URL, for example to 120 hours.

const API_KEY = "YOUR_TEST_KEY";
const API_URL = "https://api.energypriceforecast.eu/api/v1/iobroker/summary?country=de&hours=120&window_hours=4";

Important: the final authority is not only the URL, but meta.allowed_horizon_hours. That field tells you what your current access is actually allowed to use server-side.

For automations: separate "run now" from "plan later"

A common mistake is to look only at cheapest_window_start. That is enough for display, but often too rough for real control. With is_cheapest_window_now, you can directly detect whether the best price window is already active. With next_full_cheapest_window_start, you can plan the next full future window.

on({ id: ROOT + ".is_cheapest_window_now", change: "any" }, obj => {
  if (obj.state.val === true) {
    log("Best price window is active now.");
    // enable the wallbox or start EV charging
  }
});

Pragmatically speaking: for EV charging, heat pumps, or batteries, a boolean for "now" is more robust than comparing one future timestamp.

Which states the script creates

Errors and limits