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When should the washer, EV or heat pump run? This workflow turns day-ahead prices, carbon intensity and the German power mix into a visual daily plan.

What the page shows

  • An accessibly labelled 24-hour power clock.
  • Price curve for today and tomorrow, negative hours and a live marker.
  • Power mix and carbon, a 7×24 heatmap and best consecutive windows.
  • Example calculations for five devices with an adjustable surcharge.

How the workflow works

  1. Start: The Schedule Trigger runs hourly at minute 10. A webhook also provides an immediate manual test run.
  2. Fetch: Four HTTP nodes request aWATTar prices, renewable signal, carbon intensity and the public Energy-Charts power mix in parallel.
  3. Merge: The Merge node waits for all four responses and passes them together to the Code node.
  4. Normalise: The code aggregates quarter-hours into hours, assigns every point to Europe/Berlin and handles daylight-saving changes.
  5. Plan: It finds the cheapest and lowest-carbon consecutive windows from one to four hours, builds the 7×24 heatmap and calculates five appliance examples.
  6. Publish: The last HTTP node sends validated JSON to strom-ingest.php with a secret X-Strom-Token.
  7. Store safely: PHP validates the token, ranges and array sizes, atomically replaces the live file and creates the social poster. The page then reads only that static JSON file.

Use the workflow yourself

Download the JSON, import it into n8n and replace the example URL and YOUR-SECRET-TOKEN in “Publish planner”. The target server needs strom-ingest.php and the same server-side token. Test once through the webhook before activating the hourly schedule.

Wholesale price is not your bill

The value is the net DE-LU day-ahead wholesale price. Taxes, grid fees, levies, VAT and supplier margin are excluded. The slider adds 17 ct/kWh as an example only. No savings are guaranteed and this is not advice to switch supplier.

Data: aWATTar; Energy-Charts.info / Fraunhofer ISE; Bundesnetzagentur | SMARD.de (CC BY 4.0). The site is not affiliated with these providers.

Download the n8n workflow as JSON or see more experiments in the n8n collection.

When does your washer run – and when should it run?

Originally published at daniele-michelin.com. More guides, free checks (SPF, TLS, headers) and an error-message lexicon: daniele-michelin.com/en/.