Profiting from change: the shift to 15-minute MTU in the day-ahead market

From 30 September 2025, the day-ahead auction will clear in 15-minute intervals, a structural change to better reflect the volatility of renewable generation. An ongoing question is whether early adopters may see advantages during this transition.  

In this article, we look at a simplified example of the potential profit and loss when trading 1 MW per hour according to the hourly production profile, considering only the outcomes in the imbalance market. We present two examples: a high-solar, low-demand day and a Dunkelflaute day. In both cases, we can observe distinct price patterns, mostly driven by mismatches between the hourly (H) and quarter-hourly (QH) profiles. By acting early on these patterns, traders can limit losses and support grid stability. 

What to expect: DA-IDA1

In the absence of empirical DA data, the first Intraday Auction (IDA1), traded only 3 hours after the DA gate closure but in 15-min resolution, can give us a preview of what could lie ahead. 

This market exhibits the well-known “sawtooth pattern”, where prices generally peak during the initial quarter-hour and drop at the last quarter-hour. During solar ramp-up, IDA1 prices are generally higher than DA in the first two QH and lower in the last two. The reverse tends to occur during the evening ramp-down. 

This behaviour can be explained by the mismatch between hourly generation profiles and actual quarter-hourly output: 

• In the first two QH, the hourly profile tends to overestimate actual generation. As a result, traders hold short positions and are required to buy back, which drives IDA1 prices above DA prices.
• In the last two QH, the hourly profile generally underestimates actual generation. As a result, traders hold long positions and must sell back, leading to ID prices falling below DA prices. 

A practical example: A sunny day  

On a sunny, low-demand day such as Sunday, 17 August 2025, Germany experienced both positive and negative imbalance prices. In this simplified example we assume a trader is trading 1 MW per hour and we consider losses and profits from the Imbalance market only. As shown in table 1, the financial outcome for a trader depends on whether their position aligns with system needs. Overproducing in times of surplus or underproducing in times of scarcity translates into losses. 

Despite the overall result being positive on this sunny, low-demand day, identifying the pattern caused by differences between hourly and quarter-hourly solar profiles could have decreased losses by around €330. 

Is this just about solar?

No, these patterns occur when demand shifts and generation ramps must be matched to the hourly profile. For example, on 11 December 2024, DA prices spiked to €445/MWh due to the Dunkelflaute. Wind output, already low, continued to decrease in the morning, causing the first two quarter-hours to fall below spot prices, similar to a solar ramp-down. Even in this scenario, the sawtooth pattern is clearly observable.

On such days, even small deviations can trigger large imbalance penalties and significant financial losses. On this day, the imbalance price spiked to €5,359/MWh. Trading 1 MW per hour solely on the hourly profile would have resulted in €1,531 loss. Despite wind profiles showing greater variability than solar, the patterns of discrepancies between 15-minute and hourly profiles are still observable, and avoidable. 

Looking ahead: flexibility in the green transition 

As the market evolves to support the green transition and better integrate renewable generation, accurate 15-minute forecasts and flexible trading strategies will become increasingly essential. By identifying systematic patterns between hourly forecasts and actual quarter-hourly generation or demand, traders can strategically reduce imbalance risks and contribute to grid stability. These patterns aren’t limited to the well-known solar ramp sawtooth effect, they also appear during demand shifts and generation ramps. And even as more participants adopt 15-minute strategies and these patterns become less pronounced, the value of flexibility, high-resolution forecasts, and precise 15-minute data will remain critical.