Naturgy's Appeal Against New Voltage Control Rules: What Changes for Electric Generators in 2026

Key data

Electric generators in Spain face significant regulatory uncertainty: the new dynamic voltage control obligations approved by the CNMC on June 25, 2026 are already being challenged in court. Naturgy Generacion, S.A. and Naturgy Ciclos Combinados, S.A. have filed an administrative litigation appeal before the National Court, registered as ordinary procedure 4/790/2026 before Section 4 of the Administrative Litigation Chamber.

The resolution published in the BOE on October 23, 2026 summons interested parties to appear as defendants. The deadline is nine days from that publication, making this news urgent for any sector operator who wants to defend their position in the proceeding.

What does this regulation establish?

The CNMC resolution of June 25, 2026 modified the electric operating procedures 7.4 and 14.4 with the objective of promoting dynamic provision of the voltage control service. This service is essential for maintaining electrical grid stability: it ensures that voltage remains within safe operating ranges at all times.

The fundamental change is the shift from a static model to a dynamic one: instead of complying with fixed voltage control requirements, generators would be required to adapt their response actively and continuously according to grid conditions. This implies greater technical and operational demands for generating plants.

The summons resolution published on October 23, 2026 does not resolve the merits of the case: it simply notifies interested parties that an active appeal exists and gives them the opportunity to appear as defendants to defend the validity of the CNMC resolution.

Economic and operational impact

The outcome of this litigation has direct consequences on the operational obligations of all energy producers in Spain. There are two possible scenarios:

• If the National Court confirms the CNMC resolution: operating procedures 7.4 and 14.4 in their dynamic version are consolidated. Generators must adapt their facilities and control systems to comply with the new requirements, assuming the investment and operational costs involved.
• If the National Court annuls the CNMC resolution in whole or in part: the application of the new dynamic obligations would be halted, with possible return to previous procedures or opening of a new regulatory process.

While the litigation is active, generators find themselves in a situation of regulatory uncertainty: they must decide whether to invest in adapting to the new procedures or wait for the judicial outcome. This lack of clarity has a real cost in investment planning, maintenance contracts, and operational strategy.

Additionally, the fact that two subsidiaries of a large energy group like Naturgy have appealed indicates that the new obligations are perceived as economically significant or technically controversial in the sector.

Who does it affect?

• Electric generators subject to operating procedures 7.4 and 14.4: combined cycle plants, ordinary regime power stations, and other producers connected to the transmission grid.
• Grid operators who manage voltage control services in the Spanish electrical system.
• Energy sector companies with legitimate interest in the outcome of the litigation, who may appear as defendants within 9 days of October 23, 2026.
• Legal advisors and regulatory consultants who advise companies in the electrical sector on regulatory compliance and regulatory strategy.
• Investors and financiers of electric generation projects in Spain, for whom regulatory certainty is a key factor in risk assessment.

Practical example

A company operating a combined cycle plant in Spain—such as those managed by Naturgy Ciclos Combinados, S.A., one of the appellants—is directly affected by operating procedures 7.4 and 14.4. With the CNMC resolution of June 2026 in force, that plant should adapt its voltage control systems to a dynamic model, which may involve investments in hardware, control software, and technical training.

If that same company considers that the new obligations are disproportionate or technically unfeasible within the established timelines, it has two options: join the appeal by appearing as a defendant before the National Court (within 9 days of October 23, 2026, that is, before approximately November 1), or continue adapting to the regulation assuming the risk that the court annuls it later and the investment was wasted.

This dilemma—invest now or wait for the ruling—is exactly what all electric generators affected by OP 7.4 and 14.4 face at this moment.

What should companies do now?

1. Assess whether you are an interested party: if your company operates electric generation facilities subject to operating procedures 7.4 and 14.4, you have legitimate interest in the outcome of procedure 4/790/2026.
2. Act before the 9-day deadline: the summons published on October 23, 2026 grants only 9 days to appear as a defendant before Section 4 of the Administrative Litigation Chamber of the National Court. After that deadline, you cannot join the proceeding.
3. Consult with legal advisors specialized in energy law: the decision to appear or not in the appeal has strategic and legal implications. A lawyer specialized in electrical regulation should assess the convenience and available arguments.
4. Review your investment plan for voltage control: while the litigation is active, assess whether it is advisable to accelerate or postpone investments in adapting to the new procedures, depending on your tolerance for regulatory risk.
5. Monitor the progress of the judicial proceeding: the outcome of appeal 4/790/2026 before the National Court will determine whether the dynamic obligations of OP 7.4 and 14.4 are consolidated or annulled. Maintain active monitoring of judicial resolutions.

Official source

Consult complete regulation in official source

Notice: This article is for informational purposes only and does not constitute legal advice. For specific decisions, consult a qualified professional. Source: https://www.boe.es/diario_boe/txt.php?id=BOE-A-2026-22224