WattWhen: Smart Energy DE

Hack your electricity bill. WattWhen visualizes German spot prices and calculates savings for your EV & appliances. Privacy-first & free data. Try it!

Stop overpaying for electricity. See exactly when power is cheap, green, or even free.

WattWhen is the ultimate energy planner for Germany, helping you navigate the "Solar Paradox." While grid fees are fixed, the stock market price of electricity changes every hour—often dropping to zero or going negative when the sun is shining. WattWhen helps you shift your heavy usage to these "Happy Hours" to save money and reduce grid strain.

WHY WATTWHEN? Germany produces record amounts of solar and wind energy. Don't let it go to waste! Whether you have a dynamic electricity tariff (like Tibber or Rabot) or just want to use energy when it's greenest, this app is your daily dashboard.

KEY FEATURES: • Live Spot Market Prices: See Day-Ahead prices from the EPEX SPOT market (sourced via SMARD.de) for Germany & Luxembourg. • Shift & Save Scheduler: Drag-and-drop your appliances (Washing Machine, Dryer, Dishwasher) to see the exact cost difference between running them now vs. later. • EV Charging Planner: Optimize your Electric Vehicle charging windows to hit the lowest possible kWh price. • Balcony Solar Sim: Thinking of buying a "Balkonkraftwerk"? Simulate how an 800W panel would lower your specific daily costs. • CO2 Insights: See when the grid is powered by renewables vs. coal.

DESIGNED FOR PRIVACY • No account required. • No personal data collection. • All calculations happen locally on your device.

DATA SOURCE Market data is provided by the Bundesnetzagentur (SMARD.de) ensuring government-grade accuracy for the DE-LU bidding zone.