---
title: "15-Minute Day-Ahead Market & Forecast Quality | alitiq"
description: "Why the shift to 15-minute contracts doesn't automatically mean better forecasts for renewable energy trading."
url: https://alitiq.com/en/blog/quarterly-market-forecasting
language: en
alternates:
  en: https://alitiq.com/en/blog/quarterly-market-forecasting
  de: https://alitiq.com/de/blog/viertelstunden-markt-prognose
---

[Back to Blog](https://alitiq.com/en/blog)

Energy Trading

Forecasting

Solar

Wind

Markets

# The 1/4-Hourly Day-Ahead Market & The Illusion of Better Forecasting

September 30, 2025

Daniel Gröger

![The 1/4-Hourly Day-Ahead Market & The Illusion of Better Forecasting](https://alitiq.com/images/blog/day-ahead-viertelstuendlicher-fahrplan.webp)

For those not deeply in the energy industry: Electricity from 🌬️ wind and ☀️ solar PV power plants is often traded in the short-term on the EEX – the European Energy Exchange. Think of it like a stock exchange, but for energy.

## The Shift to 15-Minute Intervals

📊 Traditionally, short-term contracts were traded in 15-minute intervals (intraday), while the day-ahead market worked with hourly intervals. Now, the shift is happening: the day-ahead market is moving to 15-minute contracts.

✅ **Advantage:** This makes balancing easier in theory.

⚠️ **But beware:** It doesn't mean forecasts suddenly become more accurate.

## Why Forecasts Don't Automatically Improve

Why? Because numerical weather prediction (NWP) models struggle to capture sub-hourly cloud development 🌥️, even in the short term. For very short horizons, we can use satellite images 🛰️ to improve solar forecasts (something we're working on at Alitiq with Ventus Technologies in the NowcastAI project).

👉 But for day-ahead forecasts, such real-time data isn't available. The expectation that balancing becomes much easier might therefore be an illusion.

## The Technical Reality

I illustrated this using forecasts from the DWD ICON-D2 model. It produces 15-minute forecasts – but here's the catch:

- The model integrates weather equations over 1–2 minutes
- Results are aggregated into quarter-hourly steps
- This introduces "noise" 🌪️ – forecasts might capture the overall trend (e.g., decreasing afternoon solar production), but often not at the right time or location

### Hourly vs. 1/4-Hourly Market Schedule

![Hourly Day-Ahead Market Schedule](https://alitiq.com/images/blog/day-ahead-stuendlicher-fahrplan.webp)

Hourly Day-Ahead Market Schedule

*Figure 1: Actual solar irradiance vs. 1h day-ahead market schedule*

![1/4-Hourly Day-Ahead Market Schedule](https://alitiq.com/images/blog/day-ahead-viertelstuendlicher-fahrplan.webp)

1/4-Hourly Day-Ahead Market Schedule

*Figure 2: The expectation - Actual solar irradiance vs. 1/4-hourly day-ahead market schedule*

### Forecast Accuracy Comparison

![1/4-Hourly Day-Ahead Forecast](https://alitiq.com/images/blog/day-ahead-viertelstunden-prognose.webp)

1/4-Hourly Day-Ahead Forecast

*Figure 3: Actual solar irradiance vs. 1/4-hourly day-ahead forecast from ICON-D2*

## The Bottom Line

📉 Metrics actually look worse when comparing native quarter-hourly forecasts. Interestingly, accuracy improves if you just calculate hourly averages.

💡 **Bottom line:** "Skill is all you need." In forecasting, skill means one forecast performs better than another. What we really need now is skill in sub-hourly forecasting – not just finer time intervals.

* * *

*At alitiq, we're working on advanced forecasting solutions that address these challenges, combining multiple data sources and AI-driven approaches to deliver truly accurate short-term predictions for the energy market.*

### Ready to Transform Your Business?

Discover how alitiq's forecasting intelligence can optimize your operations.

[Contact Us](https://outlook.office.com/bookwithme/user/a4a08a92ad764515bccc3a29740b96ff%40alitiq.com?anonymous&ismsaljsauthenabled=true)