The Brazilian Association of Energy Storage Solutions (ABSAE) published on October 1, 2026 a response to representatives of the thermal power segment who question the entry of batteries into the Capacity Reserve Auctions (LRCAP). The debate arose after the Ministry of Mines and Energy released the auction schedule through 2029 and opened the way for storage systems, whether batteries or pumped hydro plants, to compete for contracts alongside generation sources. For the association, the criticisms about stability and short-circuit current do not hold up in light of the technical rules already defined by ONS and EPE.
What thermal plants question and what the rule requires
Critics claim that chemical batteries do not help keep voltage and frequency stable and that they have a strong short-circuit current limitation. ABSAE points out that MME Normative Ordinance No. 136/2026, which guides the December battery auctions, requires projects to use grid-forming inverters, in accordance with the joint technical note NT-ONS DPL 0111/2025 / EPE-DEE-NT-095/2025.
Unlike the conventional inverter, which merely follows the grid and injects current, the grid-forming inverter creates its own voltage and frequency reference and behaves much like a synchronous generator. It can also operate as a virtual synchronous generator (VSG), reproducing through control the inertia of rotating machines. Among the requirements of the technical note are:
- response to phase jumps and voltage variations at the connection point within 16 ms;
- frequency reaction within 200 ms and full response within 1 s, with participation in primary regulation;
- synthetic inertia and Q-V and P-f droops with parameters adjustable by ONS;
- continuous voltage control and the ability to generate and absorb reactive power;
- passive impedance behavior between 0.1 Hz and 120 Hz, without creating or worsening oscillations;
- stable operation in islanding and an option for autonomous start (black start).
Short circuit is a local issue, and the auction already addresses it
Regarding the short-circuit level, the association argues that the contribution of any plant is limited to its electrical vicinity and depends on topology, nearby sources, circuit breakers and protections, aspects that ONS assesses bus by bus. Because they take up little space and are modular, batteries can be installed next to existing substations, where the grid needs reinforcement. LRCAP itself provides for a locational bonus based on the MISCR indicator (multiple-infeed short-circuit ratio), which favors grid-forming projects at weak-grid points.
International references cited
ABSAE mentions that the United Kingdom pioneered the inclusion of grid-forming capability in the grid code, and that the operator NESO procures inertia and short-circuit current from batteries and renewables. In Australia, about 74% of battery projects in the connection queue already plan for grid-forming inverters, and Transgrid has selected up to 2 GW of these systems, an effect compared to that of 17 synchronous condensers. In California, gas-fired generation fell 60% in the first five months of 2026 compared to 2024, while battery capacity grew 79%, to 16 GW. In Texas, on July 22, batteries discharged about 12 GW during the record demand peak.
What changes in practice for BESS developers
ABSAE's defense reinforces that, in Brazil, competition in LRCAP will be technical and attribute-based. For those working in the storage chain, this translates into concrete points:
- Developers should prioritize areas near substations with weak grids, where MISCR can yield a locational bonus.
- Inverter manufacturers and suppliers need to prove grid-forming performance within the times and functions required by the ONS/EPE technical note.
- EPCs will have to integrate controls, protections and connection studies compatible with these requirements from the basic design stage.
- Everyone should follow the system needs assessment that EPE and ONS present by April 30 each year, as it will define the attributes of each annual auction.
The association maintains that, for power needs of up to about four hours, batteries are already the most economical option, which is likely to make competition between technologies more intense in upcoming auctions.
Original source: ABSAE — Um portfólio de potência mais seguro e eficiente passa pelos Sistemas de Armazenamento de Energia em Baterias