By Brazil Stock Guide – The Brazilian electricity regulator, Aneel, is preparing to begin reviewing requests for outlay on energy storage systems (ESS) installed alongside power generation plants, even as its specific regulations for the technology remain under development. The move comes as part of efforts to incorporate energy storage into the country’s transmission grid, a process carried out in collaboration with the Ministry of Mines and Energy (MME), the National Electric System Operator (ONS), and the Energy Research Company (EPE).
In an official communication to the wind and solar energy associations Abeeólica and Absolar, Sandoval Feitosa, the head of Aneel, confirmed that the agency would begin reviewing the requests under existing legislation and technical criteria. “Although the specific regulation for these systems is still under preparation and approval, considering the importance of these solutions for the operation and safety of Brazil’s electrical system and the pilot projects already presented to the agency, we inform that we will begin processing requests for outlay for energy storage systems (ESS) installed at the same site as generation plants,” Feitosa said.
The decision aims to enhance the flexibility of the National Interconnected System (SIN) by supporting the development of new storage projects. Currently, seven projects have already applied for this type of system. Feitosa explained that the main goal is to mitigate the impact of forced generation cuts, known as “curtailment,” which occur when there is an oversupply of power or when transmission infrastructure is insufficient to accommodate all generated electricity.
“Curtailment” involves reducing the output of renewable energy plants, such as wind and solar farms, when supply exceeds demand, or when there are limitations in the grid’s transmission capacity. While this helps prevent grid overload, it leads to financial losses for producers, who are unable to generate energy despite favorable weather conditions. The energy sector estimates the losses due to curtailment have already surpassed R$ 5 billion.
The move by Aneel follows communications sent to the MME, ONS, and EPE in late August, signaling the agency’s readiness to include energy storage systems in the national planning process. According to the documents, the MME is already exploring the use of batteries in key points of the grid, as a replacement for traditional infrastructure reinforcements. Moreover, ONS highlighted several critical incidents in 2025, including on May 4 and August 10, when excess solar energy generation and low demand nearly caused a blackout due to overproduction.
These events underscore the potential of energy storage solutions to balance the grid, storing energy during the day and discharging it when demand is higher at night. Despite these developments, the final regulations for integrating energy storage systems remain stalled due to ongoing discussions over tariff issues. Feitosa’s statement follows remarks by Brazil’s Minister of Mines and Energy, Alexandre Silveira, who confirmed that a government auction for battery systems is expected to reach a demand of 2 GW (gigawatts).
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