On June 25, 2026, the Brazilian Electric Energy Agency (“ANEEL”) published the regulation of energy storage systems (“ESS”), consisting of Normative Resolutions (“REN”) No. 1,161/2026 and No. 1,162/2026, in addition to amendments to Modules 1, 2, 3 and 5 of the Transmission Services Rules. The measure results from the closing of Public Consultation No. 39/2023 and fills a relevant regulatory gap for the sector.
REN No. 1,161/2026 addresses the requirements and procedures necessary for obtaining, transferring and changing technical characteristics related to authorizations for ESS operated in a standalone manner.
REN No. 1,162/2026, in turn, promotes amendments to structuring regulations of the electric sector, such as:
- REN No. 1,000/2021, which addresses the electricity distribution service;
- REN No. 846/2019, which addresses penalties in the electricity sector;
- REN No. 1,071/2023, which addresses requirements for obtaining authorization for wind, photovoltaic, thermoelectric and hybrid generating plants;
- REN No. 875/2020, which addresses requirements for obtaining authorization for exploitation of hydropower projects;
- REN No. 921/2021, which regulates general conditions applicable to holders of authorizations for exploitation of generating plants or energy storage systems;
- REN No. 1,029/2022, which consolidates procedures for obtaining operational status and defining installed capacity; and
- Modules 1, 2, 3 and 5 of the Transmission Services Rules, which address access rules to the Main Grid.
It is worth highlighting that these measures are part of a broader regulatory movement for the development of the ESS market in the country, including the publication of Normative Ordinance No. 136/2026 by the Ministry of Mines and Energy (“MME”), on June 3, 2026, which establishes the guidelines and the framework for the first Capacity Reserve Auction, in the form of power, aimed at contracting new battery ESS.
Below we highlight the main points addressed in the regulation:
1. Authorization granting
REN No. 1,161/2026 establishes the requirements and the necessary documentation to instruct the request for authorization to exploit standalone ESS, whose term is 35 years.
REN No. 1,161/2026 sets a period of 54 months for the entry into commercial operation of the asset, counted from the publication of the authorization, subject to monitoring by inspection and, in specific hypotheses, possible extension.
At the same time, Article 3, §1, of REN No. 1,029/2022 now provides that agents holding authorization for energy storage must request from ANEEL authorization for the commencement of test or commercial operation, including in the case of a new storage unit or reversible generating unit.
With regard to infrastructure, Article 12 of REN No. 1,161/2026 prohibits the sharing of metering, control and auxiliary service systems among adjacent ESS, requiring the functional individualization of each unit.
Regarding extension, Article 16 innovates by detailing the conditions to be analyzed by ANEEL in a possible request for extension of the authorization term, which must be submitted at least 6 months prior to the end of the term.
Furthermore, the REN expressly highlights that the authorization does not remove the technical risks associated with connection and use of the grid, and the agent remains subject to the penalties provided for in REN No. 846/2019 in case of non-compliance with regulatory obligations.
2. Changes to technical characteristics
Requests for postponement of the implementation term or for change of technical characteristics will only be analyzed upon proof of commencement of works, pursuant to Article 13 of REN No. 1,161/2026.
Even so, a certain flexibility is admitted to the agent, which may, at its own account and risk, implement necessary technical changes, subject to subsequent validation by ANEEL.
Under Article 13, §5, of REN No. 1,161/2026, the distributor or the National Electric System Operator (“ONS”), as applicable, may issue an Access Opinion or execute the contract for use of distribution or transmission systems prior to ANEEL’s authorization of the change of technical characteristics, and the applicant is not required to present to the distributor or ONS the filing of the request for such change.
3. Reversible hydropower plants
REN No. 875/2020 now allows concessionaires and authorized entities to request from ANEEL the inclusion of pumping units or reversible generating units in existing projects.
The inclusion of reversible generating units must be treated as a change of technical characteristics, while the inclusion of pumping units will be recorded in the authorizing acts, in both cases subject to submission of an Executive Summary.
4. Access to the transmission system
Module 5 of the Transmission Services Rules now establishes that, for ESS fully dispatched by the ONS, the amount of use of the transmission system (“MUST”) in the consumption modality shall be considered null, and the charging of the system shall not be included in its own load. For generation projects (including hybrids or associations) with co-located storage, the generation MUST may be increased by the discharge power of the ESS, reflecting its additional energy injection capacity.
In addition, the presence of storage allows greater contractual flexibility: the injection MUST may be reduced by up to 30% without cost, provided that there is technical proof of this compatibility in the Access Opinion.
5. Access to the distribution system
REN No. 1,000/2021 now provides in Article 127 that, when a generating plant or standalone ESS uses the same connection point to consume and inject energy, a single Distribution System Use Contract (“CUSD”) must be executed on a permanent basis. In the case of units dispatched by the ONS, a Transmission System Use Contract (“CUST”) will also be required, in addition to the applicable distribution contracts. For standalone ESS, execution of an operating agreement is also required.
Article 148, §3, clarifies that consumer units with co-located ESS, without distributed microgeneration or minigeneration, may not inject power into the grid, and the contracted injection demand must be set to zero.
Article 149 of REN No. 1,000/2021 also establishes specific parameters for demand contracting, and in the case of generating plants with co-located storage and standalone ESS, their own sizing criteria apply. On the other hand, for consumer units with co-located ESS, the contracted demand associated with storage may be considered equal to zero.
6. Demand response and ancillary services
REN No. 1,009/2022 now establishes that consumers with co-located ESS may participate in the Demand Response Program.
It further provides that ancillary services may be rendered both by standalone ESS and by generating plants with co-located ESS, subject to compliance with technical and operational requirements.
7. Financing
REN No. 921/2021 now contains an express provision that authorized entities may offer, as collateral for financing for the execution of works and services, the rights arising from the respective authorization, as well as the assets comprising the generating plant or ESS, provided that enforcement does not compromise continuity of generation.
8. Penalties
REN No. 846/2019 now includes infractions specifically related to ESS. In this context, the following conducts are penalized, when related to ESS:
- failures in complying with registration obligations;
- non-analysis or lack of record of occurrences;
- non-compliance with legal and regulatory provisions regarding maximum human exposure limits;
- absence of proper accounting or recording of investments, costs and revenues; and
- operation of facilities without proper implementation of metering systems.
Additionally, the REN establishes parameters and criteria for calculating fines, which may be based on estimated annual ESS revenue.
9. Transitional provisions
Article 18 of REN No. 1,161/2026 establishes an adaptation regime for pending authorization requests, granting a period of 90 days for compliance with the new requirements, under penalty of rejection.
Within the scope of REN No. 1,162/2026, Articles 17 and 18 assign obligations to the ONS and to the Electric Energy Trading Chamber (“CCEE”), both with a period of 180 days counted from publication of the regulation.
The ONS must submit to ANEEL a proposal to update the Grid Procedures to incorporate ESS specificities and assess the inclusion of technical requirements related to grid-forming technologies or other solutions aimed at system quality and stability.
The CCEE must submit to ANEEL a proposal to adapt the Trading Rules and Procedures so as to reflect the new regulatory framework for ESS.