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A new era in European energy markets: The introduction of 15-minute trading
The European Union’s Single Day-Ahead Coupling (SDAC) mechanism has reached an important milestone: from 1 October 2025, 15-minute time-based trading (Market Time Unit, MTU) was introduced across all bidding zones and cross-border interconnections in the European electricity market. This new system replaces the previous hourly time slots and also extends to the intraday market (Single Intraday Coupling, SIDC), including full integration of Greece’s bidding zones.
The introduction of the 15-minute MTU represents a key landmark in the development of the European energy market: it can better integrate renewable, weather-dependent generation, allow more dynamic pricing, and open new horizons for flexible consumption and energy storage. From a technical standpoint, the transition went smoothly; the coming period will show how it reshapes market operations and mindsets.
For a long time, the European electricity market considered hourly trading sufficient. Consumption patterns – lighting, heating, industrial demand – followed a slower rhythm, which the hourly system reflected well. On the supply side, generation variability was typically manageable on a case-by-case basis, without the need for quarter-hourly time resolution. However, the rapid growth of solar PV radically changed this situation. Today, cloud cover can cause significant output fluctuations within minutes – changes that can no longer be managed effectively on an hourly basis. As a result, the expansion of solar generation increased the need for a 15-minute trading unit.
At the same time, the latest demand-side trends are also reshaping electricity trading. Electrification means a growing share of heating demand is connected more directly to electricity markets through heat pumps, which exhibit noticeable load variations even within very short time windows. Another challenge is the spread of electric vehicles: charging often requires high power over a short interval, and the market must adapt in near real time.
These processes – which emerged over the past 5–10 years and are expected to accelerate and become dominant in the coming decades – have highlighted the need for more dynamic pricing and finer time resolution. The 15-minute trading unit introduced on October 1, 2025, thus represents not just a technical reform but a response to the changing patterns in production and consumption.
The transition is particularly important in one respect: by applying the 15-minute MTU in the SDAC1 and SIDC systems, the market can respond more quickly to variable and often less predictable generation, such as wind and solar. According to an article published on September 30 by Montel, a Europe-based energy news portal and think tank, the transition – carried out with the participation of thirty transmission system operators (TSOs) – went smoothly in the 27 SDAC and 25 SIDC countries shown in Figure 1. As of December 2025, Great Britain, Switzerland, Cyprus, Malta, some of the Western Balkans, Ukraine, Moldova and Türkiye remained outside the SDAC/SIDC European market-coupling framework.
Figure 1: SDAC (left) and SIDC (right) member countries as of late 2025, Source: ENTSO-E
According to Pierre Milon, Head of Market Coupling and Integration at Epex Spot in Paris, which conducts day-ahead auctions in eleven European countries, their company received a significant number of 15-minute products. Many market participants and data analysts expressed satisfaction with the surprisingly smooth transition.
However, some voices stressed the need for caution. As several traders pointed out, greater time resolution can increase the risk of errors and contribute to market volatility during the transition phase, as illustrated in Figure 2. One trader also noted that their company had been using the 15-minute intervals in the intraday market, but the prices in the day-ahead auction differed significantly from their expectations: instead of around 160 euros/megawatt-hour (MWh), they were only around 116.57 euros/MWh.
Montel’s analyses also suggest that the quarter-hourly trading leads to greater price volatility, which aligns with prior expectations. This is not necessarily a disadvantage: more dynamic pricing creates opportunities for energy management and storage. By exploiting price differences, battery storage facilities can complete multiple charge-and-discharge cycles per day, improving their return on investment and contributing to system flexibility. Volatility, therefore, is both a risk and a new opportunity for the market.
Moreover, the shorter time scale allows more granular alignment of generation and trading schedules, which can reduce balancing costs over the long run. However, this comes with technical challenges: the Euphemia auction algorithm must perform more complex calculations, so results are published a few minutes later than before. Market tools adapted quickly to handle quarter-hourly bids, but the physical reality – power plants and systems designed for hourly operation – will adapt more gradually.
Figure 2: Price differences between hourly and quarter-hourly intraday trading on HUPX on 1 October, 2025, Source: HUPX Labs
In summary, the 15-minute trading system fundamentally changes the market’s ability to support flexibility. It allows participants to adapt effectively to fluctuations in renewable generation. The volatility that accompanies the new system also triggers a longer-term learning process in the market, requiring new strategies and operating practices.
In the consumer segment, benefits will accrue most directly to digitally connected consumers – those with smart meters, smart-grid solutions, electric vehicles, or heat pumps. For them, the quarter-hourly time scale can create added value. These benefits, however, will materialise most clearly in countries where regulations allow time-of-use pricing and retail tariffs reflect real-time market prices.
This post is a reprint of an article written by our colleague, which was originally published on December 19, 2025, in the online journal CEEnergy News.
