Regulation of battery energy storage systems (BESS) has been postponed again. ANEEL (National Electric Energy Agency), after a new request for review, this time presented by director Willamy Frota.
The decision, taken at a meeting this week, once again halts the completion of a process considered strategic for the modernization of the electricity sector.
The postponement comes at a time of increasing demand for storage solutions, especially given the growth of renewable energy sources and recurring episodes of generation restrictions.
Motivations
In justifying the request for a review, Willamy Frota indicated the need to deepen the technical and legal analysis of the issue, based on the points raised in the dissenting opinion of director Fernando Mosna.
Frota also reported that he intends to conduct a new consultation with the Federal Prosecutor's Office. ANEEL and to engage in dialogue with the technical teams and advisors of the other members of the board.
Among the factors that motivated the postponement are the complexity of the subject and its impacts on the functioning of the electrical system, including issues related to curtailment and the integration of new technologies.
The decision also follows the agency's internal procedure, which provides for a collective review of the process, extending the time needed for a final decision.
Mosna vote
The dissenting opinion of director Fernando Mosna, which forms the basis of some of the discussions, proposes significant changes to the model originally presented in the public consultation. The main objective is to reduce costs and eliminate barriers to the adoption of batteries in the electrical system.
One of the key changes is the elimination of the so-called "dual tariff." According to the director's proposal, storage systems would only pay for grid use when energy is injected into the system, and not also when charging the batteries.
The argument is that the stored energy is not intended for final consumption, but for temporary displacement for later reinjection into the system. Another point is the increased flexibility of the MUST (System Usage Amount).
Mosna proposes allowing an immediate reduction of up to 30% for agents that install storage systems associated with generation, in contrast to the previous rule that provided for a gradual reduction over six years.
The ruling also addresses the TFSEE (Electricity Services Inspection Fee), arguing that there is no legal basis for charging it on storage systems until there is specific regulation for this category.
Furthermore, adjustments were made to the definition of closed-cycle reversible power plants, with the aim of clarifying their regulatory framework and avoiding ambiguities.
Long process
The regulation of energy storage in ANEEL It has been under discussion since Public Consultation No. 39/2023, but has faced successive postponements.
The process has been stalled since August 2025, when Mosna himself requested an initial review, raising concerns about the proposed tariff model.
Since then, changes to the legal framework (such as the enactment of Law 15.269/2025) have required additional technical revisions, prolonging the debate.
The Agency's technical areas maintained a favorable understanding regarding the charging of fees for both loading and unloading, a position that differs from the proposal presented in the dissenting opinion.
The process also involves adjustments to existing regulations and tariff procedures, as well as the need for adaptations to the company's own internal systems. ANEEL.
With the new request for review, the definition of rules for energy storage remains without a deadline for completion, maintaining market expectations for a regulatory framework considered essential to enable investments in batteries in the country.
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A ANEEL Who is all this apparent bureaucracy protecting? What interests are behind this decision?
It's certain that the citizen will be the one who loses out. Where are the representatives? Where is the Public Prosecutor's Office?