From December 2, Red Eléctrica de España (REE) transforms energy storage access to the electricity system by publishing its specific capacity in the transmission grid nodes.

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This methodological change, responding to a long-standing demand from the sector, redefines how availability at critical points is calculated, paving the way for more effective integration of storage projects.

“This is something we’ve been asking for a very long time, but it’s just one more step forward,” says Eugenio Domínguez, Vice President of AEPIBAL.

With this publication, developers will be able to identify precise opportunities to install storage systems in strategic locations that promote decongestion and optimization of the electricity system.

Until now, these facilities were regulated in the same way as conventional generation, preventing them from competing on equal terms for grid access.

The Criteria for Grid Access

The access capacity at grid nodes was traditionally calculated based on three criteria:

1. Short-Circuit Criterion: Evaluates the short-circuit power requirements, more relevant for synchronous generators.
2. Dynamic Criterion: Considers the grid’s dynamic stability, essential for operational security.
3. Static Criterion: Determines how much energy can be transported through the lines.

The change focuses on the third criterion, which until now treated storage as a generator operating at full capacity at all times. This resulted in storage being unable to access congested nodes during peaks in renewable generation, even if its operation was intermittent and coordinated with demand.

The new methodology introduces a specific profile that operates as demand during renewable generation surpluses and as generation during consumption peaks.

“This approach will free up capacity at critical nodes, especially in areas with an excess of photovoltaic generation,” Domínguez told Energía Estratégica España.

New Reporting by REE

The information published by REE will be included in the monthly nodes status report. From now on, this document will feature a dedicated column distinguishing the capacity allocated to conventional and renewable generation.

According to AEPIBAL’s Vice President, this segmentation is crucial: “It will reveal more capacity, and the important thing is that it will be in places where it can truly be useful.”

This means developers will have access to specific data that allows them to plan projects in areas where storage can decongest the grid and improve system stability.

The data will include:

• Node location.
• Total capacity available for storage (in MW).
• Specific restrictions based on technology type or operational profile.
• Current node status (congested, partially available, or unrestricted).

This structure will enable developers to quickly assess the viability of their projects and present the required guarantees to access capacity.

Immediate Opportunities and Sector Expectations

The publication of this information represents a unique opportunity for developers, who can secure capacity in real time under a first-come, first-served allocation system.

Capacity will be allocated on a first-come basis, meaning developers who promptly submit the necessary guarantees will secure their access first.

This has sparked significant anticipation in the sector, with many expected to monitor the data release closely to seize real-time opportunities.

“This evening, the sector didn’t sleep,” Domínguez remarks, describing how “all developers were waiting for the moment to see which capacity becomes available and assess which of their projects are most feasible.”

He anticipates a swift occupation of the newly released capacity, driven by strong interest in developing storage in strategic areas.

However, this measure is only the first step. “We’re going to have a very, very busy 2025 to resolve and adjust all of this,” the executive adds.

Regulatory Framework

This change aligns with the Resolution of June 27, 2024, by the Comisión Nacional de los Mercados y la Competencia (CNMC), which establishes technical details for calculating generation access capacity.

During the transitional period ending today, grid operators adjusted their calculations and adapted their systems to ensure the accurate publication of this new information.

“We’ve seen significant proactivity from Red Eléctrica in implementing this quickly, which shows that everyone is rowing in the same direction, and that’s highly positive,” Domínguez concludes, highlighting the collaboration among regulators, administration, and private actors.

This progress marks a milestone in Spain’s energy transition, positioning storage as a fundamental pillar for integrating renewable energy and ensuring the stability of the electrical system.