From hour to quarter hour: A new era on the EPEX SPOT exchange

From Kurt Kretschmer

From June 11, 2025, the European power exchange EPEX SPOT will be facing a groundbreaking change. The day-ahead auction, which has both the largest trading volume and is the central case study for European electricity pricing, will be expanded: in future, market participants will not only be able to trade in hourly blocks, but also in quarter-hourly products.

However, the actual change in the auction mechanism is much more far-reaching. The adjustment of the clearing price in Single Day-Ahead Coupling (SDAC): In future, the market price will be determined on a 15-minute basis – the so-called Market Time Unit (MTU). This means that the clearing price will no longer be calculated on an hourly basis, but for each individual quarter-hour segment.

What is behind SDAC and why is this change so important?

SDAC forms the backbone of the European internal electricity market. It ensures that supply and demand from different bidding zones are brought together efficiently – taking into account the available cross-border transport capacities. This results in an optimal day-ahead price for each bidding zone, which maximizes overall economic welfare.

Map: Single day-ahead coupling (SDAC)

A look back shows the immense importance of these market mechanisms: In June 2024, an IT problem at EPEX SPOT led to a partial decoupling of the day-ahead market. The result? Germany became an “electricity island” and the price in the German-Luxembourg bidding zone exploded to over EUR 2,300/MWh – while it would have remained below EUR 100 with functioning market coupling.

Chart: Exchange electricity prices and trading volumes | Energy-Charts

Why the switch to 15-minute products?

The switch to a 15-minute MTU is a logical step in the harmonization of the European electricity market. The balancing energy price and intraday prices are already calculated at quarter-hour intervals. The day-ahead market will now follow in order to coordinate all market segments even better.

The advantages of this change:

• Cost reduction: More efficient allocation of grid capacities and procurement of balancing energy.
• Reduction of inefficiencies: Smaller time intervals lead to more accurate pricing.
• A more stable and fairer market: More precise price determination promotes more efficient electricity trading in Europe.

What does that mean for all of us?

This innovation is much more than a technical adjustment – it is a milestone on the way to a more efficient and sustainable energy market for consumers, companies and society.

What impact will the changeover have on the German market in particular?

In part 2 of our series, energy market experts Dr. Christof Petrick and Kurt Kretschmer analyze the new opportunities, challenges and market shifts that the 15-minute products bring with them, especially for Germany. Stay tuned!