The choice of title for this article alludes to the work The Man Who Counted (O Homem que Calculava), by Malba Tahan [1], in which Beremiz Samir resolves seemingly trivial everyday problems through method and logical rigour. The parallel with the Brazilian electricity sector in 2026 is not coincidental. Just as in the enigmas faced by that fictional protagonist, many of the challenges confronting Brazil's electricity sector require less improvisation and a greater capacity for systematic analysis.
The system faces enigmas that manifest themselves in the operation of the National Interconnected System (Sistema Interligado Nacional – SIN), in the growing incidence of curtailment, in the increasing need for flexibility and dispatchable capacity, in the imperfections of price signals and in the integration of energy storage. To this picture must be added the challenge of implementing, in a coordinated and secure manner, the free market opening already enshrined in legislation, in an environment of growing technical, economic and regulatory complexity.
In this context, the regulation of Electrical Energy Storage Systems (Sistemas de Armazenamento de Energia Elétrica – SAE) stands as one of the principal institutional enigmas of 2026. Law No. 15,269/2025 conferred an express legal basis for ANEEL's authority to regulate the storage sector, but the regulatory model remains in consolidation. The debate over the incidence of the Transmission System Use Tariff and Distribution System Use Tariff (TUST/TUSD) [2] on the charging and discharging of batteries generated a deadlock within the Agency's Board of Directors in August 2025, when a request for further review and the suspension of proceedings [3] under Public Consultation No. 39/2023 were filed.
The proceedings were recently resumed with the publication of Joint Technical Note No. 3/2026, which maintained, at the technical level, the logic of tariff incidence in both directions of energy flow and indicated that any structural revision would be addressed within the scope of the tariff modernisation process foreseen in the 2026–2027 Regulatory Agenda. The technical area also indicated that the consolidation of the matter should occur through two complementary normative instruments: a specific resolution to govern the authorisation of SAEs, and another, of a cross-cutting character, to integrate them into the rules on network access and use, energy trading and charges.
However, at the 5th Ordinary Public Meeting of ANEEL's Board of Directors, held on 10 March 2026, the matter once again generated intense regulatory debate. The dissenting vote presented by Director Fernando Mosna proposed the removal of TUST/TUSD charges at the moment of charging the autonomous SAE, retaining only the tariff incidence associated with the injection of energy into the grid. The proposal reignited discussions on tariff equity and the allocation of electricity infrastructure costs. Given the disagreements among the directors — which also encompassed the regulatory definition of closed-cycle reversible hydroelectric plants and the need to reassess a legal opinion in light of Law No. 15,269/2025 — the matter was ultimately withdrawn from the agenda, remaining pending a final deliberation.
Another significant enigma for this year concerns the capacity reserve mechanism. Following its incorporation into the legal order by Law No. 14,120/2021 [4] and the holding of the first Capacity Reserve Auction (Leilão de Reserva de Capacidade – LRCAP) in 2021, the expectation of annual auctions was not borne out in subsequent years. In 2026, however, the mechanism regained concrete form: the 2nd LRCAP was held on 18 and 20 March.
The outcome was broadly considered a success by the government and by market participants, in that it enabled the contracting of additional dispatchable capacity and unblocked significant investment flows, albeit not without controversy regarding its tariff impacts and the actual necessity of the contracted volumes.
The auction was also accompanied by institutional challenges, with requests for suspension referred to the Federal Court of Accounts (Tribunal de Contas da União – TCU), which demonstrated that the environment remains susceptible to contestation until the adjudication and ratification of results, expected for May. From this perspective, the conventional-source model appears to have advanced, even if amid controversy. Uncertainty has, however, shifted towards the storage LRCAP, whose implementation continues to raise questions about whether it will in fact be carried out, notwithstanding growing market expectations and ministerial commitments.
In the field of infrastructure, 2026 revisits a classic enigma under new pressures: how to develop new transmission corridors capable of delivering renewable generation, particularly from the North and North-East regions, to the major consumption centres in the South-East and the South, avoiding bottlenecks that amplify operational constraints and system costs.
The answer lies in the forthcoming transmission auctions and in the acceleration of network expansion investments. At the same time, the impending expiry of numerous transmission concessions adds complexity to planning, requiring decisions on extensions and re-tendering at precisely the moment when the network must anticipate the new frontiers of generation.
On the consumption side, another 2026 enigma involves the improvement of time-of-use tariff signals, a subject being discussed under the banner of the so-called New White Tariff (Nova Tarifa Branca) [5]. ANEEL has launched a series of workshops to discuss the enhancement of hourly tariff signals, placing the role of price formation as an instrument of efficiency and demand management back at the centre of the debate. The proposal rests on the premise that consumers can respond to differentiated prices throughout the day, shifting consumption and contributing to peak load reduction.
The challenge, however, is not only regulatory but informational: for the signal to function, it must be comprehensible, transparent and accompanied by adequate metering. Without clarity in communication and predictability in criteria, the tariff risks becoming more complex than effective. In this context, the rollout of smart meters emerges as a key enabling factor, though its expansion still depends on regulatory coordination, institutional maturity and significant investment.
If 2025 was the year of structural reforms [6], 2026 will be the year of regulatory engineering. ANEEL's 2026–2027 Regulatory Agenda embodies this transition by concentrating efforts on storage regulation, tariff modernisation, the consolidation of capacity reserve mechanisms, the adaptation of trading rules and the phased implementation of the free market opening.
The challenge shifts from the legislative to the operational: translating legal mandates [7] into coherent, predictable and technically sustainable regulatory arrangements, capable of interacting with one another and preserving the sector's economic equilibrium.
In a year marked by geopolitical tensions and elections, events that may well ripple through the regulatory calendar of the electricity sector, the temptation to simplify complex debates will be considerable. Yet, as The Man Who Counted teaches, sophisticated problems are not resolved through shortcuts, but through method.
The consolidation of the new free market architecture, the integration of storage, the expansion of the transmission network and the improvement of price signals will all require consistent technical decisions and sustained institutional coordination.
The true enigma of 2026 is not to identify the challenges, they are already apparent, but to demonstrate that the Brazilian electricity sector possesses the regulatory maturity to structure, with precision and responsibility, the next stage of its evolution.
[1] Pen name of Professor Júlio César de Mello e Souza.
[2] Transmission System Use Tariff / Distribution System Use Tariff.
[3] Case No. 48500.904885/2020-63.
[4] Article 3 of Law No. 10,848/2004: 'The Granting Authority shall ratify the quantity of electricity or capacity reserve to be contracted to meet all national market requirements and the list of new and existing undertakings that will form part of the tendering process, as a reference list.'
[5] The subject was under discussion in Public Consultation No. 046/2025.
[6] Promoted by Provisional Measure No. 1,300/2025 and Provisional Measure No. 1,304/2025, converted respectively into Laws No. 15,235/2025 and No. 15,259/2025.
[7] Introduced by Law No. 15,269/2025