Integrations

The forecasts can be integrated into evcc to control when your car is charged.

Here's how:

1. Install evcc (see EVCC documentation)
2. Create an API key under API Keys
3. Set your fixed costs and VAT in your profile:
   • Go to Edit profile
   • Enter your fixed costs (in cents per kWh)
   • Enter your VAT rate (in %)

   The price is then calculated using the formula <code class="bg-gray-50 px-2 py-1 rounded text-sm font-mono">(Preis + fixed_cost_cent) * (1 + vat / 100.0)</code>.

4. Add the following code to your EVCC configuration file: (see also EVCC.io documentation)
   evcc.yaml

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   tariffs:
     grid:
       type: template
       template: energyforecast
       token: YOUR_API_TOKEN
       charges: # Additional fixed surcharge per kWh (e.g. 0.05 for 5 cents) (optional)
       tax: # Tax, additional percentage surcharge (e.g. 0.2 for 20%) (optional)
   

5. Restart EVCC and you should be able to see the forecasts in the app.

Before integration, only EPEX Spot day-ahead prices are available.

After integration

ioBroker is an open-source IoT platform that is especially popular in Germany. The JavaScript adapter fetches the forecast and exposes it as data points.

Here's how:

1. Install ioBroker (see ioBroker documentation)
2. Create an API key under API Keys
3. Set your fixed costs and VAT in your profile:
   • Go to Edit profile
   • Enter your fixed costs (in cents per kWh)
   • Enter your VAT rate (in %)
4. Install the JavaScript Adapter in ioBroker
5. Create a new script with the following content:
   javascript

   Copy

   // Create the data points (only needed on the first run)
   createState("javascript.0.energyforecast.data", "[]", { type: "string" });
   createState("javascript.0.energyforecast.price_now", 0, { type: "number", unit: "ct/kWh" });
   createState("javascript.0.energyforecast.cheap_now", false, { type: "boolean" });
   
   // Fetch and cache the forecast (every 6 hours)
   async function fetchForecast() {
     const res = await httpGetAsync("https://www.energyforecast.de/api/v2/forecast?token=YOUR_API_TOKEN");
     setState("javascript.0.energyforecast.data", JSON.stringify(JSON.parse(res.data).data), true);
   }
   
   // Determine the current quarter hour from the cached data (every 15 minutes)
   function evaluate() {
     const slots = JSON.parse(getState("javascript.0.energyforecast.data").val || "[]");
     const now = Date.now();
     const upcoming = slots.filter(s => new Date(s.end).getTime() > now).slice(0, 96);
     if (upcoming.length === 0) return;
   
     const cheapest = [...upcoming]
       .sort((a, b) => a.total_ct_kwh - b.total_ct_kwh)
       .slice(0, 16)
       .map(s => s.start);
   
     setState("javascript.0.energyforecast.price_now", upcoming[0].total_ct_kwh, true);
     setState("javascript.0.energyforecast.cheap_now", cheapest.includes(upcoming[0].start), true);
   }
   
   schedule("0 */6 * * *", async () => { await fetchForecast(); evaluate(); });
   schedule("*/15 * * * *", evaluate);
   fetchForecast().then(evaluate);
   

6. This gives you the data points price_now, cheap_now and data. The forecast is fetched every six hours and evaluated every 15 minutes. Use them in Blockly or JavaScript to switch devices at cheap times.

The flow separates fetching from evaluating: one tick pulls the forecast every six hours and stores it in the flow context, a second one evaluates it every 15 minutes and decides whether to charge right now.

Here's how:

1. Install Node-RED, either standalone or as a Home Assistant add-on.
2. Open the menu at the top right, choose Import, then paste the flow below.
3. Wire the output of the evaluation node to a call service node that switches your wallbox.

[
  {
    "id": "ef_fetch_tick",
    "type": "inject",
    "name": "Every 6 hours",
    "repeat": "21600",
    "once": true,
    "onceDelay": "5",
    "wires": [["ef_fetch"]]
  },
  {
    "id": "ef_fetch",
    "type": "http request",
    "name": "Energyforecast",
    "method": "GET",
    "ret": "obj",
    "url": "https://www.energyforecast.de/api/v2/forecast?token=YOUR_API_TOKEN",
    "wires": [["ef_store"]]
  },
  {
    "id": "ef_store",
    "type": "function",
    "name": "Cache the forecast",
    "func": "flow.set('energyforecast', msg.payload.data);\nreturn null;",
    "outputs": 1,
    "wires": [[]]
  },
  {
    "id": "ef_eval_tick",
    "type": "inject",
    "name": "Every 15 minutes",
    "repeat": "900",
    "wires": [["ef_eval"]]
  },
  {
    "id": "ef_eval",
    "type": "function",
    "name": "Cheapest quarter hours",
    "func": "const size = 16;\nconst slots = flow.get('energyforecast') || [];\nconst now = Date.now();\nconst upcoming = slots.filter(s => new Date(s.end).getTime() > now).slice(0, 96);\nif (upcoming.length === 0) { return null; }\nconst cheapest = [...upcoming].sort((a, b) => a.total_ct_kwh - b.total_ct_kwh).slice(0, size);\nconst cheapNow = cheapest.some(s => s.start === upcoming[0].start);\nmsg.payload = cheapNow ? 'on' : 'off';\nmsg.priceNow = upcoming[0].total_ct_kwh;\nreturn msg;",
    "outputs": 1,
    "wires": [[]]
  }
]

Afterwards msg.payload holds on or off, and msg.priceNow holds the current total price in ct/kWh.

openHAB can query our API directly through the HTTP binding, without any extra add-on.

Thing http:url:energyforecast "Energyforecast" [
    baseURL="https://www.energyforecast.de/api/v2/forecast?token=YOUR_API_TOKEN",
    refresh=21600,
    timeout=30000
] {
    Channels:
        Type string : forecast "Forecast" [ stateTransformation="JSONPATH:$.data" ]
}

String Energyforecast_Forecast  "Forecast"
    { channel="http:url:energyforecast:forecast" }
Number Energyforecast_Price_Now "Current price [%.2f ct/kWh]"
Switch Energyforecast_Cheap_Now "Cheap charging window"

rules.JSRule({
  name: "Energyforecast",
  triggers: [triggers.GenericCronTrigger("0 */15 * * * ?")],
  execute: () => {
    const slots = JSON.parse(items.Energyforecast_Forecast.state || "[]");
    const now = Date.now();
    const upcoming = slots
      .filter(s => new Date(s.end).getTime() > now)
      .slice(0, 96);
    if (upcoming.length === 0) return;

    const cheapest = [...upcoming]
      .sort((a, b) => a.total_ct_kwh - b.total_ct_kwh)
      .slice(0, 16)
      .map(s => s.start);

    items.Energyforecast_Price_Now.postUpdate(upcoming[0].total_ct_kwh);
    items.Energyforecast_Cheap_Now.postUpdate(cheapest.includes(upcoming[0].start) ? "ON" : "OFF");
  }
});

If you know your way around, you can easily retrieve data via the API and use it in your project. The API documentation can be found at Swagger / Open API Documentation

Endpoints

Parameters

Try it quickly

curl "https://www.energyforecast.de/api/v2/forecast?token=YOUR_API_TOKEN"

If you build an integration that could be useful to others, let us know. We appreciate every integration and are happy to help spread the word.