Plan energy use in Homey with prices and grid CO₂

Install it in four steps

1. Open the Homey Test page.
2. Accept the Test-channel notice and install the app on your compatible Homey.
3. Add the Price & CO₂ Forecast device and follow the guided setup.
4. Select its Flow cards to switch, charge, heat or notify at the right time.

How the forecast is built

The price logic is not “forecast only”. It deliberately works in two stages so real market data always wins as soon as it exists.

Advanced alternative: HomeyScript and raw API access

Most users should install the native app above. For custom scripts, Homey still gets its own summary path whose structure and naming are tuned for HomeyScript and Advanced Flow.

Alternative: full price series for custom logic

If you want to compare prices yourself, calculate thresholds or select custom time windows instead of only using ready-made signals, use the Homey price series.

mode=mixed uses official day-ahead prices as soon as they are available and only fills the remaining horizon with forecast values. Real quarter-hour prices stay quarter-hourly; hourly forecasts are returned as four equal quarter-hour slots.

const API_KEY = '';
const url = 'https://api.energypriceforecast.eu/api/v1/homey/prices?country=de&hours=48&mode=mixed&resolution=15m';

const response = await fetch(url, {
  headers: API_KEY.trim() ? { Authorization: `Bearer ${API_KEY.trim()}` } : {},
});
if (!response.ok) throw new Error(`HTTP ${response.status}`);

const data = await response.json();
const next12Hours = data.entries.slice(0, 48);
const prices = next12Hours.map(slot => Number(slot.value)).filter(Number.isFinite);
if (prices.length === 0) throw new Error('No valid prices received');
return Math.min(...prices);

This example returns the lowest base price in the next twelve hours as a Number. Values are market prices without taxes and grid fees by default.

What the API actually returns

The Homey endpoint returns a compact automation view. That matters because in Homey you usually do not want to start with a full raw time series but with a few clear values for flows.

Time horizon and resolution

The examples use hours=48 and window_hours=4. That is a sensible starting point, but not the full product limit.

How to use it in Advanced Flow

1. Install HomeyScript.
2. In Advanced Flow, add a time trigger, for example every 15 minutes.
3. Then add a HomeyScript card with return type Number, Yes/No or Text.
4. Paste one of the copy-paste blocks below.
5. Use the result tag in the next flow step.

Homey explicitly describes HomeyScript as a way to access website APIs. The examples below use exactly that with the Homey summary endpoint.

Example 1: return the current price as Number

Use this if you want to build threshold-based or comparison logic.

const API_KEY = '';
const url = 'https://api.energypriceforecast.eu/api/v1/homey/summary?country=de&hours=48&window_hours=4';

const response = await fetch(url, {
  headers: API_KEY.trim()
    ? { Authorization: `Bearer ${API_KEY.trim()}` }
    : {},
});

if (!response.ok) {
  throw new Error(`HTTP ${response.status}`);
}

const data = await response.json();
const price = Number(data.flat?.current_price);
if (!Number.isFinite(price)) throw new Error('No current price received');
return price;

Example 2: is the best price window active right now?

For real automations this is often more useful than only knowing the next start time.

const API_KEY = '';
const url = 'https://api.energypriceforecast.eu/api/v1/homey/summary?country=de&hours=48&window_hours=4';

const response = await fetch(url, {
  headers: API_KEY.trim()
    ? { Authorization: `Bearer ${API_KEY.trim()}` }
    : {},
});

if (!response.ok) {
  throw new Error(`HTTP ${response.status}`);
}

const data = await response.json();
return data.flat?.is_cheapest_window_now === true;

Example 3: return the next full start as Text

Useful for planning, dashboards or notifications.

const API_KEY = '';
const url = 'https://api.energypriceforecast.eu/api/v1/homey/summary?country=de&hours=48&window_hours=4';

const response = await fetch(url, {
  headers: API_KEY.trim()
    ? { Authorization: `Bearer ${API_KEY.trim()}` }
    : {},
});

if (!response.ok) {
  throw new Error(`HTTP ${response.status}`);
}

const data = await response.json();
return String(data.price?.next_full_window?.start || '');

Optional with API key

If you want to test more than the free horizon, place the key directly in the script. The API currently expects a Bearer header.

const API_KEY = 'YOUR_API_KEY';
const url = 'https://api.energypriceforecast.eu/api/v1/homey/summary?country=de&hours=120&window_hours=4';

In the end, the authoritative value is not just what you ask for in the URL, but what the server actually allows in meta.allowed_horizon_hours.

Typical Homey use cases

Important meta fields for debugging