Brazil's National Electric System Operator (ONS), together with ANEEL and EPE, published the remaining capacity of the National Interconnected System (SIN) that will serve as a reference for the country's first stand-alone BESS auctions , called "LRCAP 2026 – National Storage and LRCAP 2026 – Storage", scheduled for December 2 and 4 , respectively.
The results show strong contrasts: there are busbars with margins close to 3000 MW and more than 50 combinations of connection point and voltage level with virtually zero availability.
The highest individual value identified corresponds to Arinos 2, in Minas Gerais, with 2960 MW at 500 kV , followed by Janaúba 3 with 2920 MW and Jaíba with 2575 MW.
Likewise, in northern Minas Gerais and western Bahia , 22 bars accumulate about 22 GW if their individual margins are added together, but the whole is limited to 3,200 MW .
Meanwhile, in another extensive region encompassing parts of Bahia, Piauí and Ceará, 41 busbars collectively exceed 28 GW , compared to a regional ceiling of just 3670 MW .
However, all the values mentioned do not automatically equate to usable power because each installation is subject to additional limits per subarea and electrical area . Therefore, this condition will be decisive in December.
As a result, developers will need to simultaneously read the individual limit, aggregate restrictions, and technical conditions associated with each point , since the network does not allow linearly summing all published values.
The publication comes after a record registration, considering that the Energy Research Company initially registered more than 6,000 projects for 296.8 GW , although that volume will have to go through the technical analysis process and only in November will it be known how many projects and capacity will be able to participate in the auctions.
The ONS note now incorporates another critical variable: how much margin is actually left in the electrical infrastructure to connect storage .
The methodology establishes three levels. The first corresponds to the candidate busbar , that is, the limit of each individual point. Above this are the subarea restrictions, which group several installations, and finally the area restrictions, which set a maximum overall limit for larger electrical regions.
Igaporã III clearly illustrates this logic. The 230 kV busbar individually supports up to 2,000 MW , but the Bom Jesus da Lapa–Igaporã subarea has a combined limit of 900 MW .
Futura presents a similar situation. The 500 kV point reaches 2,165 MW , while the Sobradinho subarea restricts the whole to 1,500 MW .
The limits are not derived solely from the available power flow. The ONS combined physical availability, static and dynamic performance, and short-circuit analysis to determine the final margins.
The short circuit also significantly alters some results. For example, at Guaíba 3, 230 kV , the static and dynamic behavior would allow for 1,140 MW . However, a 40 kA circuit breaker at the Cidade industrial substation, for which replacement is not recommended, reduces the final margin to just 150 MW .
In Capivari do Sul, at 230 kV , the same type of restriction reduces the value from 650 MW to 100 MW . Meanwhile, the Fortaleza region presents another example: seven points are constrained by 31.5 kA circuit breakers at 69 kV , elements that currently require management through operational maneuvers.
The restrictions also explain why more than 50 combinations appear directly with 0 MW , with a high concentration in the northern and northeastern regions. Meanwhile, other cases are not due to electrical behavior but to a more basic limitation: a lack of physical space within substations for new connections .
In general terms, of the approximately 380 units analyzed, about 15% have no remaining margin . This leaves around 85% with some level of availability, although subject to the higher restrictions and specific conditions established by the study.
Location becomes central to developers' strategy
Each value must be cross-referenced with the aggregate limits, operational restrictions, and works required to enable access.
Some notes associated with the busbars even establish direct obligations for the entrepreneur , such as performing sectioning on their own or replacing switches as a condition for proceeding with the connection.
For investors and developers, this could change the market's perception, as a site with a nominal capacity of 2,000 MW may be more constrained than one with a lower individual figure , depending on the regional ceiling, existing infrastructure, and necessary interventions.
Economic analysis will also be a factor. According to the ANEEL Regulatory Impact Analysis provided as background information, the effective cost of storage systems is between 63% and 83% lower than the cost of the last power reserve contract. Furthermore, the technology can reduce certain charges related to operational restrictions.
The market looks ahead to December with a registered volume of 296,807 MW , but the ONS publication makes it clear that the magnitude of registrations is only one side of the process.