ANEEL is set to define the costing model today for the initial battery storage system auctions, a pivotal step for the sector’s viability.
This Tuesday, September 1st, ANEEL (Brazil’s National Electric Energy Agency) is holding a crucial public hearing to advance energy storage in Brazil. The meeting aims to discuss the guidelines for the first two bidding processes to contract large-scale battery systems, marking a significant milestone for the sector’s expansion.
The meeting, scheduled for 2:30 PM in Brasília, is highly anticipated by the market. The main focus is on defining how the financial charges to support these new services will be distributed, directly impacting the economic attractiveness of the projects.
A recent technical note from ANEEL presented three proposals for allocating these costs, with a recommendation focused on a model that considers the operational flexibility of each generator, adjusting contributions accordingly.
Two Strategic Auctions Scheduled for December
The public hearing will address the details of Public Consultations No. 22 and No. 23 of 2026, outlining the tenders, annexes, and contracts for the Capacity Reserve auctions. The first, Auction No. 05/2026, will take place on December 2nd and will focus on National Storage, requiring batteries to be Brazilian-made.
Then, on December 4th, Auction No. 06/2026 will be held, focusing on General Storage, without the manufacturing origin restriction. Both auctions will contract the power availability of autonomous storage systems through 15-year contracts, with supply expected to begin in August 2028. Interested parties have until September 14th to submit their contributions.
Costing Definition: The Core of the Debate
The method of costing the services provided by batteries has been one of the most delicate and debated points. Law No. 15,269 establishes the sharing of charges among generators, but the practical application of this provision generates controversy.
The debate is intensified by the origin of the need for storage, frequently associated with the intermittency of renewable sources such as wind and solar, and the limitation of grid infrastructure. Batteries emerge as a solution to mitigate curtailment (mandatory generation curtailments).
The proposal to include hydro and thermoelectric power plants in the cost allocation, especially those with greater flexibility, faces resistance from some sectors. It is argued that other beneficiaries, such as energy distributors, would not participate in the cost sharing.
Cost Allocation Models Under Discussion
ANEEL presented three main models for cost allocation: an equal division among all generators; exemption for so-called “flexibility providers”; or an allocation proportional to the degree of operational flexibility of each plant.
The agency’s technical recommendation leans towards the third model, as it believes it offers greater alignment with the charge’s objective, cost stability, technical clarity, and regulatory viability. In this model, generators with greater flexibility would contribute about 25% of the charge, while those with less flexibility could bear up to 100%.
The agency assesses that an equal division would not generate the appropriate economic signal, and an exemption for flexibility providers could reduce the base of contributors. All three proposals will be submitted for public consultation.
Impact on Planning and Legal Certainty
The pending definition of the costing model directly affects the strategic planning of participants. Generators need to know their financial obligations to price their offers, while storage investors evaluate default risks in defining the payer base. This can influence the value of bids in the auctions.
The topic also raises questions about legal certainty and could lead to new articulations in the National Congress. Bill No. 3,716/2026, presented by Representative Arnaldo Jardim, seeks to amend the legal provision, demonstrating the relevance of the debate for the future of the energy storage sector.
