Brazil's National Electric System Operator (ONS), the National Electric Energy Agency (ANEEL) and the Energy Research Company (EPE) released, on September 30, 2026, Technical Note NT-ONS DPL 0095/2026. The document sets out the remaining capacity of the National Interconnected System (SIN) for connecting new energy storage systems, a key input for anyone planning to compete in the 2026 Capacity Reserve Auctions (LRCAPs) for batteries.
What the technical note presents
Simply put, remaining capacity indicates how much of the grid can still accept new projects at a given point without compromising the safe operation of the system. This is what the market usually calls connection margin. For storage projects, this data determines where it makes sense to install a BESS (battery energy storage system) and where the grid can no longer handle new power injections or withdrawals.
The note published by ONS jointly with ANEEL and EPE covers different levels of the electrical infrastructure:
- Basic Grid (Rede Básica), which comprises the SIN's largest transmission facilities;
- Other Transmission Facilities (DIT);
- Facilities of Exclusive Interest of Generating Plants for Shared Connection (ICG);
- Indirect connections, made through distribution systems.
Including indirect connections is relevant because it broadens the range of options for developers, who are not restricted to points directly connected to transmission.
Regulatory basis and auction modalities
The document complies with Ordinances No. 444/GM/MME/2016 and No. 136/GM/MME/2026 of the Ministry of Mines and Energy. The figures apply to the 2026 LRCAPs in two modalities: National Storage and Storage.
Capacity reserve auctions are the mechanism through which the government contracts available power to ensure demand is met at critical moments, paying developers for availability rather than only for the energy generated. Under this design, batteries stand out for responding quickly to system needs, storing energy during periods of surplus and returning it when the grid needs it most.
The joint release by the three institutions reinforces coordination among planning, operation and regulation. In practice, the capacity map becomes the official reference for the project registration and qualification stage.
Why connection margin matters so much
In grid-constrained auctions, having a technically sound project and a competitive price is not enough. If the chosen point lacks sufficient remaining capacity, the project may be left out even with a good bid. For this reason, a careful reading of the note is likely to separate viable projects from initiatives that will need to be relocated or resized.
What changes in practice for the BESS market
For the different links in the chain, the publication of the technical note opens a phase of concrete decisions:
- Developers: should cross-check their portfolios against the published figures and prioritize connection points with remaining capacity before registering projects in the 2026 LRCAPs. It may be necessary to revisit location, power rating and connection type, including the distribution alternative.
- EPCs: defining connection points allows engineering studies, substation layouts and cost estimates to move forward with greater precision.
- Manufacturers: consolidating the pipeline of eligible projects helps size the potential demand for batteries, inverters and control systems in Brazil.
- Suppliers and service providers: consultancies and electrical study and permitting firms gain a clear reference to support developers in preparing documentation.
The general recommendation is to treat the note as the starting point for planning each project. Those who analyze the data early and adjust their connection strategies will have a better chance of reaching the auction with consistent bids aligned with actual grid conditions.