Brazil's National Electric System Operator (ONS), together with the National Electric Energy Agency (ANEEL) and the Energy Research Company (EPE), published Technical Note NT-ONS DPL 0095/2026 on September 30, 2026. The document reports how much room is still available in the National Interconnected System (SIN) to receive new energy storage systems, focusing on the 2026 Capacity Reserve Auctions (LRCAPs) aimed at this type of technology. For battery (BESS) project developers in Brazil, it is one of the most anticipated technical references of this year's auction cycle.
What the technical note presents
At the core of the document is the so-called remaining capacity: broadly speaking, the amount of power that can still be connected at a given point of the grid without requiring additional reinforcements beyond those already planned. This indicator, also known in the market as connection margin, works as an initial filter. If a point lacks sufficient margin, a project that depends on it is unlikely to be viable in the auction.
The note covers three types of transmission facilities:
- Basic Grid (Rede Básica), which comprises the largest transmission facilities of the SIN;
- Other Transmission Facilities (DIT), which complement the Basic Grid;
- Exclusive-Interest Facilities of Generation Plants for Shared Connection (ICG), structures designed to evacuate power from several generation projects through a single access point.
A relevant point is that the figures also consider indirect connections, that is, those in which the storage system connects to a distribution network that, in turn, is connected to transmission. This broadens the range of options for projects that do not intend to connect directly at high voltage.
Regulatory basis and auction products
The published figures apply to both storage products of the 2026 LRCAPs: National Storage (Armazenamento Nacional) and Storage (Armazenamento). The note was prepared in accordance with Ordinances No. 444/GM/MME/2016 and No. 136/GM/MME/2026 of the Ministry of Mines and Energy.
It is worth recalling what an LRCAP is. Unlike energy auctions, which contract energy generated over time, capacity reserve auctions contract power availability: the commitment to deliver energy to the system whenever the operator needs it. Batteries fit this design well because they can respond quickly and shift energy from surplus hours to peak demand hours.
Why the connection margin matters so much
In BESS projects, the choice of connection point usually defines much of the project's risk. It affects the cost of the connection line, the implementation timeline, permitting requirements and, ultimately, the very possibility of taking part in the auction. With the joint publication by ONS, ANEEL and EPE, developers now have an official, shared reference on where there is room in the grid, allowing them to compare sites with greater confidence before submitting projects for registration.
Another aspect is competition for the same margin. When several projects target the same point, the remaining capacity tends to be contested, and not all of them fit. Knowing the figures in advance therefore helps avoid excessive concentration on a few busbars.
What this means for the Northeast
The technical note is national in scope, but we cross-referenced its data with the Northeastern substations eligible for LRCAP 2026. According to a survey by ENLACE, the note lists with connection margin 27 substations in Bahia, 24 in Ceará and all 15 analyzed in Piauí. These three states therefore account for most of the connection options identified in the region.
In practice, this indicates that the Northeast has technical room to compete in the auction, but the margin is not evenly distributed across points. Site selection must combine available capacity with other factors, such as logistical access, permitting and proximity to plants already in operation.
Our take
In our assessment, the release of the technical note signals that the storage LRCAP process is moving forward in a structured way, with the three institutions working together. We see this as positive for the battery market: predictability about the grid reduces uncertainty in the development phase and tends to improve the quality of projects reaching the auction.
At the same time, remaining capacity is a snapshot. It does not guarantee that every project submitted for a given point will be accepted, since competition for the same margin may exclude some bidders. It is also important to remember that a BESS project's viability depends on other elements the note does not address, such as equipment costs, logistics and permitting. We believe treating margin as the sole site-selection criterion would be a mistake.
In the coming weeks, it is worth following any updates or clarifications on the note, the publication of the other documents guiding the 2026 LRCAPs, and the definitions on project registration under the National Storage and Storage products. We recommend that interested parties consult the note directly on the official ANEEL, ONS and EPE websites.
What changes in practice for the BESS sector
- Developers: should review their project portfolios in light of the note's figures, prioritizing points with margin compatible with the intended capacity and assessing alternatives, including indirect connections via distribution.
- EPCs: gain more clarity on where projects are likely to concentrate, which helps with team planning, budgeting connection works and setting realistic timelines.
- Battery and inverter manufacturers: can use the margin distribution as an indicator of potential demand by region and prepare technical proposals aligned with the most sought-after points.
- Connection service and equipment suppliers: the reference to the Basic Grid, DIT and ICG signals that there will be projects at different voltage levels, with distinct needs for substations, transformers and protection.
In short, the technical note does not decide the auction, but it sets the starting point. Those who make good use of this data now are likely to reach registration with more robust projects.
Original source: ANEEL — ANEEL, ONS e EPE divulgam nota técnica sobre capacidade para conexão de sistemas de armazenamento nos Leilões de Reserva de Capacidade 2026
Paulo Melo