Brazil's grid can connect about 56 GW of batteries for December's capacity auctions
Victoria Shinder2 min readBrazil's transmission grid has about 56 GW of remaining connection capacity for battery storage projects bidding in the capacity reserve auctions scheduled for 2 and 4 December, according to a calculation by the Brazilian Association of Energy Storage Solutions (Absae), reported by pv magazine on 3 October. The figure comes from Absae's reading of Technical Note 0095/2026 from the National Electric System Operator (ONS), published on 30 September, which measures how much storage each point of the grid can still take.
Against the need. Absae estimates Brazil's power shortfall for 2028 to 2030 at 4.5 to 10 GW, so the headroom is 5.6 to 12.5 times that range. These are the association's own projections, not the auction's demand.
Where the room is. An ordinance from the Ministry of Mines and Energy, No. 136/2026, designated 129 substations for preferential treatment; projects there receive a 10% bonus in their ranking price, to steer batteries to places where they can also support the grid. According to Absae, 93 of the 129 still have connection capacity, adding up to about 13.7 GW, which on its own exceeds the top of the estimated shortfall. They are concentrated in Bahia, Piauí and Ceará and in northern Minas Gerais, with individual blocks of up to about 3.7 GW. Some sites have little or shared capacity, and some none, because of physical space, short-circuit limits or construction schedules. Non-preferred substations hold about 36 GW more.
How it feeds the auction. Under the auction rules, connection availability is taken into account when projects are ranked by substation, subarea and area. The Energy Research Office (EPE) received registrations for 6,091 projects totalling 296.8 GW. Fewer will qualify after technical analysis and connection limits, but Absae expects the eligible pool to remain far above the amount to be contracted, which it says should make price the main difference between bids.
The grid role. Absae said batteries at the favoured sites could run as grid-forming assets that support voltage, reducing the need for equipment such as synchronous condensers.
What it means
Most battery markets are held back by connection queues; Brazil's first large storage auction looks set to be limited by demand instead. With almost 300 GW registered for a need measured in single-digit gigawatts, the outcome will be decided by price and by the 10% location bonus, which makes the ONS substation list one of the most consequential documents in the process.