15-Minute and Hourly Electricity Price Resolution

Electricity prices in Europe aren’t strictly “one price per hour” anymore. Many day-ahead markets now publish prices in 15-minute intervals (quarter-hourly). In Europe’s coupled day-ahead market (SDAC), the move to 15-minute trading intervals took effect for delivery day 1 October 2025.

WattSmart supports both views so you can choose what’s practical: 15-minute precision when you care about exact timing, and a calmer hourly view when you just want to plan your day.

How price resolution works

15-minute resolution
Shows a separate price for each 15-minute interval - up to 96 intervals per day. This is the most detailed view of day-ahead prices.

Hourly resolution
Shows one price per hour - 24 points per day. In WattSmart, the hourly price is the average of the four 15-minute intervals within that hour, giving you a simpler “at-a-glance” view.

When 15-minute prices actually help

Most people don’t plan their life in 15-minute blocks - and that’s fine. The 15-minute view is mainly useful for timing inside the hour, for example:

  • Quick choices: “Boil the kettle now or in 20 minutes?”
  • Avoiding a spike: an hour can look “okay” on average but include one expensive 15-minute interval.
  • Choosing a start time: if you can start a task at 18:15 instead of 18:00, the 15-minute detail can help you pick the cheaper moment.

When hourly prices are better

Hourly resolution is often the best default for everyday planning:

  • easier to scan and compare
  • less “noise” when prices change frequently
  • great for finding the cheapest hours for typical routines (laundry, dishwasher, water heating)

Why WattSmart includes both

15-minute pricing reflects how markets can publish prices today - but hourly planning is still how most people think. WattSmart lets you switch between precision and simplicity without changing the underlying day-ahead data.

How WattSmart shows the “current” interval

Whether you use hourly or quarter-hourly prices, WattSmart highlights the current hour / current 15-minute slot in the table and on the chart — so you instantly see what you’re paying right now and where it sits in the day.

Related feature: Real-Time Price Monitoring.