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The transformation of the Spanish electricity market continues with the implementation of quarter-hourly (QH) settlement, a regulatory change that responds to European directives and aims to improve accuracy in imbalance allocation, optimize renewable integration, and increase the efficiency of the electricity system.
While this transition brings clear advantages in terms of flexibility and transparency, it also poses operational and technological challenges for retailers, producers, and other market players. In this article, we explore the regulatory framework, the impact on market operations, and how QUIXOTIC facilitates adaptation to this new model.
Regulatory Context: From Hourly to Quarter-hourly Settlement
The transition to quarter-hourly settlement in Spain aligns with European regulations, specifically Regulation (EU) 2017/2195, which sets guidelines on the operation of electricity markets in the EU. Within this framework, the reduction of the Imbalance Settlement Period (ISP) to 15 minutes is established, with the goal of improving imbalance management and renewable integration.
At the national level, Red Eléctrica de España (REE) and the Comisión Nacional de los Mercados y la Competencia (CNMC) have led the progressive implementation of this model. The key milestones of this transition are:
- December 2024: Start of imbalance settlement in 15-minute intervals (ISP15).
- March 18, 2025: Implementation of the Market Time Unit (MTU15) in intraday continuous markets and auctions.
- September 30, 2025: Last day of hourly trading in the OMIE day-ahead market.
- October 1, 2025: First delivery of energy traded in quarter-hourly products in the day-ahead market (coupled with the European market).
This new scheme is already used in the settlement of Balancing Service Providers (BSPs) and adjustment markets, but its extension across the entire electricity value chain represents a significant change in market operations. In addition, the changes have been formalized in the CNMC Resolution of March 6, 2025 (BOE-A-2025-5342), which adapts electricity operating procedures to the quarter-hourly model.
What Changes with Quarter-hourly Settlement?
Until now, the Spanish electricity market has operated with hourly resolution, where consumption and generation were measured and settled in 60-minute blocks. With the shift to quarter-hourly settlement:
- More granularity in measurement: Moving from 24 to 96 daily values for each supply point.
- Greater accuracy in imbalance settlement: Intra-hour netting is eliminated, exposing imbalances more clearly.
- Impact on market prices: An increase in price and imbalance volatility is expected, opening new opportunities for demand-side flexibility.
- Changes in energy scheduling: The intraday market has been operating in 15-minute intervals since March 2025, while the day-ahead market will follow from October 2025.
Impact on Energy Retailers
Retailers face both technical and strategic challenges to adapt to this change:
- Increased data volume: The amount of information to be processed in measurement, settlement, and billing quadruples.
- Adjustment in billing models: Migration to QH requires adapting tariff calculations and pricing structures.
- Greater volatility in imbalances: With the elimination of hourly netting, accurate forecasting and wholesale market strategies become critical.
- Adaptation to new measurement methodologies: For points without QH smart metering, interpolations from hourly values will be applied, introducing additional uncertainty in billing.
Additionally, the regulated tariff PVPC (Precio Voluntario para el Pequeño Consumidor) will begin to calculate the energy term in 15-minute intervals starting in October 2025, when quarter-hourly settlement in the day-ahead market goes live.
How Does QUIXOTIC Adapt to This Change?
QUIXOTIC is a modular subscription-based software that manages energy and multi-utility billing. Our platform is already ready to operate with quarter-hourly settlement, offering:
🔹 Automatic processing of QH data: Integrations with distributors and REE to receive and process quarter-hourly measurements.
🔹 Adapted billing: Tariff calculation and invoice generation based on the new settlement periods.
🔹 Efficient management of large data volumes: Our cloud-first architecture ensures scalability and fast processing.
🔹 Compatibility with interpolations and methodologies: We adapt billing to current measurement rules, ensuring accuracy and regulatory compliance.
🔹 Process automation: Less manual intervention, fewer errors, and higher operational efficiency.
Advantages of Billing with QUIXOTIC
The shift to quarter-hourly settlement is not only a technical challenge but also an opportunity to optimize energy management. With QUIXOTIC, retailers can:
✔ Simplify operational workload: Full automation of quarter-hourly billing.
✔ Reduce error risk: Elimination of inconsistencies in imbalance settlement.
✔ Ensure regulatory compliance: Guaranteed alignment with REE and CNMC regulations.
✔ Optimize trading strategies: Greater control over prices and imbalances.
Conclusion
Quarter-hourly settlement represents a milestone in the evolution of the Spanish electricity market. While it poses challenges in adapting information systems, measurement, and billing, it also opens the door to greater efficiency in managing the electricity system.
Retailers with flexible and scalable tools will be better positioned to take advantage of this transition. With QUIXOTIC, adapting to quarter-hourly settlement is fast, precise, and frictionless.
If you’d like to learn more about how our software can support your transition, get in touch and we’ll help you optimize your billing in this new regulatory environment. 🚀
Omar Sequera
Technology Consultant specialized in Energy
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