The Spanish electricity market is undergoing a structural transformation that will change how energy prices are set. The shift from hourly intervals to 15-minute periods, known as the quarter-hour system, represents one of the most significant changes in the last decade for energy companies in Spain and, especially, for businesses managing their energy supply. If your company aims to optimize costs and improve energy planning, understanding this new model is essential.

What is the quarter-hour system and why is it coming now?

Traditionally, Spain's wholesale electricity market has operated with hourly intervals (MTU60). This means electricity prices were set for each complete hour of the day, with a total of 24 daily prices. However, this model presents significant limitations in an increasingly dynamic energy context, dominated by intermittent renewable sources like solar and wind.

The quarter-hour system (MTU15) divides each hour into four 15-minute periods, generating 96 different prices throughout the day. This greater granularity allows for much more precise reflection of actual supply and demand fluctuations in the electrical system.

Implementation calendar in Spain

Red Eléctrica de España (REE) began settling deviations in 15-minute intervals from December 2024. Full implementation in the day-ahead market, managed by OMIE, was scheduled for September 30, 2025, with the first delivery day on October 1, 2025. This timeline ensured all market participants would be prepared for the transition.

Strategic reasons for the change

This change responds to several strategic objectives of the European electrical system:

Capture rapid variations in renewable generation.
Harmonize the Spanish market with European standards, facilitating cross-border exchanges and competitiveness.
Improve the system's operational efficiency.

How electricity prices are set every 15 minutes

Until now, businesses were accustomed to relatively stable hourly prices, but with the new model, market dynamics become much more precise and, at the same time, more complex.

To understand this clearly, it's worth keeping three key elements in mind:

The new price-setting mechanism: how supply and demand intersect in 15-minute intervals.
The volatility introduced by the system: why prices can vary more from one period to another.
The role of renewable energies: how their peaks and drops affect real-time rates.

Market mechanics

In the new system, the electricity price every 15 minutes is determined through the intersection of supply and demand curves for each interval. Producers submit their bids indicating at what price they're willing to sell energy in that specific period, while retailers and consumers communicate their purchasing needs.

The process is similar to the current hourly model, but with four times greater resolution. This granularity allows the system to capture real fluctuations much more accurately, such as unexpected demand spikes or rapid variations in renewable generation.

Impact on price volatility

This level of detail also introduces an important effect: greater volatility. What was previously averaged over an hour can now change drastically every 15 minutes. For example, photovoltaic production at 10:00 AM can differ notably from 10:45 AM if cloud cover changes.

For organizations, this translates into a new challenge: managing costs with greater precision. But it also represents an opportunity, as they can take advantage of specific periods with lower prices and adapt their processes to benefit from them.

Reflection of renewables in pricing

This transition also improves the integration of renewable energies into the market. By reflecting their variations more precisely, prices show more clearly when solar or wind energy is abundant—and therefore energy is cheaper—and when generation decreases, also affecting the price.

This will allow companies to design smarter consumption strategies, aligning their operations with moments when electricity is most competitive and sustainable.

Implications for corporate energy planning

For energy procurement managers, the quarter-hour system introduces a new dimension in planning. Electricity suppliers in Spain and their business clients will need to adapt to a much more dynamic and detailed pricing structure.

Cost forecasting becomes more complex, as small variations in consumption schedules can have significant impacts on the final bill.

Optimization opportunities

Operational flexibility: Adjust production schedules or secondary loads to consume during more economical periods.
Strategic storage: Organizations with batteries or deferred production can buy cheap energy and use or sell it during higher-price periods.
Indexed tariff: Prices that follow the wholesale market; by combining flexibility and storage, companies can reduce costs by taking advantage of the cheapest quarter-hour periods.

Adaptation strategies for companies

The first step in adapting to the quarter-hour system is to thoroughly understand your company's consumption patterns. It's not enough to know how much electricity you consume per month; you need to begin identifying exactly when you consume it, with 15-minute precision.

Operational flexibility as a competitive advantage: Adjust operating schedules or redistribute workloads to take advantage of periods with lower energy costs. Examples: charging electric fleet vehicles, producing ice, or pumping water during hours when energy costs are typically lower, without affecting the core business operations.
Collaboration with experts: Navigating the new electricity market can be complex, especially for SMEs without specialized energy departments. Partnering with an energy company like ours,with a dedicated service for businesses and SMEs that deeply understands the new system and can offer strategic advice, makes the difference between simply adapting to change or turning it into a competitive advantage.
Technology and artificial intelligence: AI and machine learning-based tools that analyze historical price patterns can help forecast future fluctuations and optimize consumption, allowing you to respond to market opportunities more quickly.
Contract review and purchasing strategy: Evaluate whether a fixed rate, which provides stability, or an indexed rate that allows you to take advantage of market opportunities, is more suitable. This is one of the most critical points, where an energy company that provides close support to businesses and SMEs can design a contracting strategy tailored to your consumption profile.

The quarter-hour system is not just a technical change in how electricity prices are set; it represents a profound transformation in how companies must manage their energy. Businesses that understand this new context and proactively adapt their energy strategy as well as their consumption patterns will gain significant competitive advantages through cost control and operational optimization.

Your next energy step

At Nordy, we understand the challenges companies face with the evolution of the electricity market. That's why we've developed solutions specifically designed to help organizations successfully navigate the transition to the quarter-hour system.

How do we support you?

Personalized analysis and proposals: We evaluate your consumption profile with high granularity to identify concrete savings opportunities.
Contracting strategy: We design the optimal combination of tariffs, power levels, and energy products adapted to your operational needs.
Continuous monitoring: We provide you with tools and alerts so you can make informed decisions about your consumption in real time.
Expert support: Our team of specialists keeps you informed about market developments and how to take advantage of them.
Energy Savings Certificate (CAE) Purchase: If you've carried out energy efficiency actions and obtained CAEs, Nordy can purchase these certificates.
Guarantees of Origin: If you want to acquire renewable energy through guarantees of origin, Nordy will provide the purchase and redemption service for your certificates, certifying that your company is environmentally friendly.

Turn market evolution into a competitive advantage for your business. Contact us for more information!

The future of the electricity market: How the quarter-hour system impacts energy planning