On September 30, 2026, the National Electric System Operator (ONS), together with the Brazilian Electricity Regulatory Agency (ANEEL) and the Energy Research Company (EPE), released Technical Note NT-ONS DPL 0095/2026. The document sets out the amounts of capacity still available in the National Interconnected System (SIN) to receive new energy storage systems, key information for anyone planning to compete in the 2026 Capacity Reserve Auctions (LRCAPs) with battery projects.
What the technical note presents
The document focuses on so-called remaining capacity, that is, the room the grid still has for new connections without compromising the secure operation of the system. In general terms, this connection margin is calculated from the operator's electrical studies, which assess whether transformers, lines and substations can handle the additional injection or withdrawal of power. For storage, this calculation becomes especially important because a battery can both absorb energy from and return energy to the grid.
The note covers different types of facilities:
- Basic Grid (Rede Básica), which comprises the highest-voltage transmission facilities of the SIN;
- Other Transmission Facilities (DIT);
- Facilities of Exclusive Interest of Generation Plants for Shared Connection (ICG);
- Indirect connections, made through distribution networks but dependent on the capacity available in the upstream transmission system.
Including connections via distribution broadens the scope of the information, since some storage projects tend to connect at lower voltages, close to load centers.
Regulatory basis and auction categories
The published figures apply to the 2026 LRCAPs in the National Storage and Storage categories. The document is based on two rules issued by the Ministry of Mines and Energy: Ordinance No. 444/GM/MME/2016 and Ordinance No. 136/GM/MME/2026, which establish the rules for determining and publishing this capacity in the context of the auctions.
LRCAPs are auctions in which the government contracts available power to ensure demand is met at times of peak system stress. Unlike auctions focused solely on energy, the goal here is to secure resources that can be dispatched when needed. Battery energy storage systems (BESS) fit this role well, as they respond quickly and can shift energy from surplus hours to hours of higher consumption.
Why the joint publication matters
The simultaneous participation of the operator, the regulator and the planning institution signals institutional alignment around the criteria used. For the market, this reduces uncertainty about which capacity reference should guide the choice of connection points. The document is available on the official websites of all three institutions.
What changes in practice for the BESS sector
With the note published, choosing a connection site is no longer a gamble and can be based on official data. The impacts spread across the value chain:
- Developers can cross-check their portfolios against the reported remaining capacity, prioritize points with sufficient margin, and discard or resize projects in saturated locations before registering for the 2026 LRCAPs.
- EPCs gain greater clarity on which projects have a real chance of moving forward, helping them plan teams, schedules and connection solutions suited to each type of facility, whether on the Basic Grid, DIT, ICG or distribution.
- Manufacturers and suppliers of batteries, inverters, transformers and control systems can better estimate potential demand and tailor technical and commercial proposals to the size of viable projects.
In practice, the recommendation is to immediately review access studies and qualification strategy in light of NT-ONS DPL 0095/2026. Those who quickly incorporate this information into their planning are likely to reach the auction with stronger projects and a lower risk of connection infeasibility.
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