The advancement of renewable sources in Brazil has brought with it a phenomenon that, until recently, seemed marginal: the curtailment — the reduction or limitation of generation determined by the National Electric System Operator (ONS) for operational reasons. Once restricted to specific situations, these cut orders have become routine in a system increasingly pressured by flow bottlenecks, network restrictions and new dispatch dynamics. Alongside wind and solar expansion, a silent liability was consolidated: the loss of revenue resulting from dispatch restrictions imposed on generation projects.
The debate about who bears this burden has been held following the Normative Resolution (REN) Aneel 1,030/2022, which differentiates cuts according to their cause. Less explored, however, is the dimension informational nature of the problem: the adequate classification of the event — and, consequently, the right to compensation itself — depends, first of all, on the transparency with which the ONS exposes the technical reasons that justify each operational restriction.
The classificatory maze
A REN 1,030/2022 establishes a dichotomous regime. On the one hand, cuts due to “electrical reliability” or “energy reasons”, attributed to the systemic operation and absorbed by the generator as its own risk. On the other, “external unavailability”, a hypothesis in which failures unrelated to the enterprise — typically limitations of the basic transmission network — trigger the right to financial compensation under the terms of the regulation.
The criteria appears simple on paper, but it hides a porous boundary. Restrictions nominally classified as “reliability” may, upon examination of the material cause, prove to be the result of structural flow bottlenecks, situations that would properly characterize external unavailability. It is in this gray area that the economic-financial balance is defined of the enterprise — and, therefore, extensiona bankability of a number growing number of projects constrained-off.
The operator’s informational duty
In this context, art. 15, §10, of REN 1,030/2022 imposes a clear obligation on the ONS: to make available, on a publicly accessible platform, all the information used in calculating generation frustration. It is not just about publishing aggregated numbers or statistical methodologies, but about exposing, in a verifiable way, the technical motivation that underpins each operational restriction.
EThis reading arises from the purpose of the standard itself. If the classification of the event determines the existence or not of compensation, restricting publicity to the results of the calculation amounts to turning the process into a black box. Transparency, here, is not a procedural adornment: it is a presupposition of external control by agents, the regulator and, eventually, the Judiciary. The duty to justify, therefore, reaches not only the data, but the causal chain itself invoked to justify the cut — regardless of the classification attributed to the event.
The expansion promoted by REN 1,109/2024
This informational duty has recently been reinforced. REN 1.109/2024 changed the art. 16, §3, of REN 1,030/2022 to impose on ONS the active advertising of the regulatory unavailability limit. Two notes are worth highlighting.
The first is semantic: the verb “disclose”, now expressed in the text, replaces the passive logic of mere availability and reinforces the duty of active publicity of the adopted parameters. The second is substantive: the change signals that fixed temporal criteria cannot prevail over the concrete causal analysis of the restriction event. In other words, form bows to content, and technical motivation returns to the center of the classificatory regime.
From transparency to legal certainty
Publicizing the reasons for the cut is not regulatory filigree. It integrates the risk allocation architecture of the electricity sector. Without knowing the material cause invoked by the ONS, the generator is unable to verify whether the assigned framework actually corresponds to the operational reality — and, if so, to question it at the administrative and judicial levels.
Information asymmetry contaminates the entire chain. Investors and financiers incorporate unpredictability as a risk premium, putting pressure on the cost of capital in renewable projects. Operative agents, in turn, submit themselves to classifications whose criteria are not fully intelligible to them. The result is a regulatory environment with fissures that compromise the predictability and, ultimately, the economic rationality of centralized dispatch.
Good governance of the curtailment It is not limited to the elaboration of compensation formulas. Rather, it depends on the quality of the information made available by the system operator. Ensuring that each cut is accompanied by public and auditable technical motivation is a condition for the dichotomy between “electrical reliability” and “external unavailability” operate according to material criteria, and not merely nominal ones. Only then will the risk allocation prescribed by REN 1,030/2022 — as perfected by REN 1,109/2024 — will be able to fulfill its promise of predictability and legal security to agents in the sector.
Marcelo Barros da Cunha e Natália Martins Ferreira are partners at MJ Alves Burle and Viana Advogados
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