Brazil has about 56 GW of remaining grid connection capacity for battery energy storage systems (BESS) participating in the December capacity reserve auctions, according to a calculation by the Brazilian Association of Energy Storage Solutions (Absae) based on Technical Note 0095/2026 from the National Electric System Operator (ONS).

The estimated headroom is 5.6 to 12.5 times the association’s projected power shortfall for 2028 to 2030, which ranges from 4.5 GW to 10 GW. At the substations receiving preferential treatment under MME Ordinance No. 136/2026, aggregate connection headroom reaches about 13.7 GW, exceeding even the higher end of the estimated shortfall.

The technical note, published on Sept. 30, measures remaining capacity at different points on the grid for storage systems that may participate in the Capacity Reserve Auctions scheduled for Dec. 2 and 4.

Absae said the distribution of connection headroom across different regions reduces the risk of widespread grid connection constraints for projects competing in the auctions. The association’s executive director, Fabio Lima, said the network has about 56 GW of available capacity, well above the power requirement it estimates for coming years, with capacity distributed across several regions.

Of the 129 substations designated for preferential treatment in the auctions, 93 have available connection capacity, according to Absae. They are concentrated mainly in the states of Bahia, Piauí, and Ceará, as well as northern Minas Gerais, with individual blocks of capacity of up to about 3.7 GW.

Some locations have smaller amounts of headroom or capacity shared among different substations, while others have no available capacity because of physical-space, short-circuit, or construction-schedule constraints.

Connection availability is considered when projects are ranked by substation, subarea, and area under the auction rules.

Substations designated as strategic under MME Ordinance No. 136/2026 receive a 10% bonus in their ranking price. The measure is intended to encourage battery installations at locations where they can provide additional grid services.

Absae said the systems planned for the auctions could operate as grid-forming assets and contribute to voltage stability. At these locations, storage could reduce the need for equipment that provides electrical support, such as synchronous condensers.

Connection headroom at non-preferred substations totals about 36 GW, according to the association’s calculation. Projects at these locations can also compete in the auctions, increasing the pool of potentially eligible developments.

Brazil’s Energy Research Office (EPE) received registrations for 6,091 projects for the auctions, totaling 296.8 GW of capacity.

The number ultimately qualified will be lower after technical analysis and the application of connection constraints, but Absae expects the number of eligible projects to remain significantly above the amount of capacity to be contracted.

The association said the combination of the connection headroom identified by ONS and the large number of registered projects should maintain competition among bidders. Lima also said adherence to the auction schedule demonstrates the sector’s commitment to meeting the deadlines and that the large number of registered projects should make price the main differentiator between bids, benefiting consumers.