The recent incorporation of energy storage into Brazil's legislative and regulatory debate has brought to light a recurring tension in the electricity sector: the attempt to accommodate new technologies within legal categories conceived for technically distinct realities. In the case of Electrical Energy Storage Systems (SAEs), this tension manifests itself clearly in the proposal to classify the autonomous SAE [1] as an Independent Power Producer (Produtor Independente de Energia – PIE), a proposal advanced by ANEEL in the context of Public Consultation No. 39/2023 (CP 39/2023). Whilst pragmatic in the short term, this solution reveals significant conceptual and regulatory weaknesses.
Under the terms of Article 11 of Law No. 9,074/1995, an Independent Power Producer is defined as a legal entity or consortium that receives a concession or authorisation to produce electricity for commercial purposes, at its own cost and risk. This is a statutory definition that unambiguously ties the PIE classification to the activity of producing electrical energy from primary energy sources. However, Legal Opinion No. 89/2025/PFANEEL/PGF, as well as recent public institutional statements by ANEEL, reinforce the view that storage is not to be equated with generation activity. The SAE does not produce new energy; it merely shifts energy already present in the system across time, providing services of flexibility, reliability and operational efficiency. It is, therefore, a functionally distinct activity whose economic and systemic rationale is ill-suited to the legal framework of the PIE.
This point was explicitly acknowledged by ANEEL Director Agnes da Costa in a public statement at an event hosted by the National Development Bank (Banco Nacional de Desenvolvimento Econômico e Social – BNDES), when she affirmed that the PIE 'garment' does not fit the storage operator. The metaphor is apt: by forcing the autonomous SAE into a framework designed for generating agents, one risks generating regulatory distortions, particularly regarding the incidence of charges, system use tariffs and trading rules, and undermining the conceptual coherence of the sector model.
The enactment of Provisional Measure No. 1,304/2025, subsequently converted into Law No. 15,269/2025 [2], represented a relevant opportunity that ultimately fell short of addressing, at the statutory level, the challenges associated with energy storage. Despite several parliamentary amendments presented during the legislative process that sought, in a convergent manner, to establish the legal figure of the energy storage operator and to set clear parameters for its activities, the Brazilian electricity sector's regulatory framework chose not to incorporate them into the final text.
By way of example, Amendment No. 119 proposed alterations to Laws No. 9,427/1996 and No. 10,848/2004 to expressly include energy storage in the list of activities regulated by ANEEL and to create the figure of the Electrical Energy Storage Agent, with defined activity profiles, rights of network access and provision for a specific tariff applicable to storage operators. Similarly, Amendment No. 95 presented a detailed proposal for the creation of an Electrical Energy Storage Agent, distinguishing between autonomous storage, co-located storage and storage associated with transmission and distribution networks, whilst also providing for revenue stacking and the classification of projects as infrastructure for the purposes of fiscal incentives.
Amendment No. 147 went even further by explicitly proposing, within the framework of Law No. 10,848/2004, the figure of the 'Storage Agent' defined as 'the legal entity responsible for the development of energy storage systems (SAEs), with the aim of ensuring the stability of the electricity grid, promoting the efficient management of energy supply and contributing to the balance between generation and consumption of electricity', and by defining its possible modes of activity and establishing a deadline for ANEEL to issue the relevant regulations.
Taken together, these amendments reveal that the legislative process presented a genuine opportunity to provide a clearer and more coherent legal structure for energy storage, an opportunity that the final statutory text did not seize. These proposals have the merit of directly addressing the problem of conceptual classification and of recognising the technical specificity of storage.
Despite this merit, the amendments also expose the limits of excessive statutory prescription. In attempting to codify in law aspects that traditionally belong to the regulatory sphere, such as technical authorisation criteria, tariff structure and trading rules, there is a risk of constraining ANEEL's room for manoeuvre and reducing the adaptive capacity of regulation when dealing with a technology still in rapid evolution. Not everything that is desirable from the standpoint of legal certainty must necessarily be exhausted at the statutory level.
What was left out of Law No. 15,269/2025 should therefore not be read merely as an omission, but also as the outcome of a legislative choice that preserves space for regulatory action. The definition of the services provided by SAEs, their remuneration, the tariff treatment of the charge-and-discharge cycle and the integration with flexibility markets are matters that require continuous technical calibration, more compatible with regulatory instruments than with rigid statutory norms.
Nonetheless, we take the view that the National Congress allowed an opportunity to pass to create, at the statutory level, the figure of the storage operator as an autonomous and novel agent in the electricity sector, a step that would have afforded ANEEL greater comfort in carrying out the regulatory process for energy storage.
In this sense, the debate surrounding ANEEL's earlier proposal to classify the autonomous SAE as a PIE serves a relevant purpose: it makes clear that storage demands a regulatory approach of its own, constructed on the basis of its function within the electricity system, rather than by analogy with pre-existing categories. Recognising that the 'garment' does not fit is the first step towards designing an institutional model that is more coherent, flexible and aligned with the objectives of Brazil's energy transition.
[1] A system that absorbs electrical energy entirely from the grid and subsequently returns it or offers services to the electrical system, operating autonomously, as defined in ANEEL's proposed definition.
[2] Published on 25 November 2025.