A study by Volt Robotics, released this Monday (22), revealed that, between January and August 2025, 17,6% of the energy that could be generated by wind and solar plants was “cut” by the ONS (National System Operator).
The main reason was the lack of demand to absorb the renewable energy supply. This curtailment rate is already more than three times higher than that recorded throughout 2024.
According to the consultancy, considering the value of contracts in the regulated market, generation cuts represented R$3,2 billion in losses in the first seven months of 2025 alone. From October 2021, when the ONS began publishing the data, until August 2025, accumulated losses reached R$6 billion.
O curtailment It is a technical decision by the ONS that determines the temporary interruption of energy generation, whether due to lack of demand, unavailability of transmission or the need to preserve the reliability of the system.
For generators paid based on the volume actually produced, as in the case of Proinfa contracts and reserve auctions, the impact is direct on revenue.
Free market agents, who need to guarantee contractual delivery, are obliged to purchase energy on the market to honor their commitments.
Data from the ONS, monitored and analyzed by the consultancy, indicate that, in August of this year alone, solar plants suffered cuts of 36% of their generation potential: 1,3 GWh were wasted, generating losses equivalent to R$240 million.
In the case of wind farms, cuts reached 21% in August, with almost 3 thousand GWh cut and a loss of R$ 641 million.
In total, according to Volt, around 4,3 thousand GWh were not generated in the month and the loss for renewable generators totaled R$881 million.
The outages were concentrated in Minas Gerais (37,8%), Ceará (33,5%), Rio Grande do Norte (30,3%) and Pernambuco (29,4%). They occur mainly between 9 a.m. and 16 p.m., with greater intensity on weekends.
Structural causes and accelerated growth of cuts
For volt robotics, the current crisis is a consequence of years of strong incentives for renewable expansion, driven by falling costs and technological advances in solar and wind power. However, without adequate infrastructure and system flexibility, the cuts have intensified:
- 2022: 51 MWm cut (Jan-Aug)
- 2023: 150 MWm (+195%)
- 2024: 987 MWm (+557%)
- 2025: 3.256 MWm (+230%)
The consultancy compares the current situation to previous water crises. "What's expected of all leaders is a sense of urgency similar to that of the crises of 2014, 2015, and 2021—not to mention 2001. On those occasions, there was widespread mobilization to secure energy supplies. Now, with Brazil putting its future as a renewable powerhouse at risk, shouldn't we have the same urgency?" the consultancy points out.
Eight proposals to address curtailment
The study lists emergency measures to reduce cuts and mitigate losses:
1. Accelerate transmission works – expand the flow capacity from the Northeast to the Southeast.
2. Curtailment auctions – create mechanisms to stimulate consumption during peak times, with lower prices.
3. Compensation for generators – regulate financial compensation for energy not generated due to system constraints.
4. Smart tariffs – accelerate the installation of smart meters and adopt differentiated prices to encourage consumption during peak times.
5. Greater flexibility in hydroelectric generation – reduce production during off-peak times, freeing up space for renewables.
6. MMGD Management – encourage adjustments in distributed generation, adoption of storage and multi-part tariffs in new projects.
7. Flexibility of thermal generation – renegotiate contracts or invest to reduce the inflexibility of plants.
8. V2G (Vehicle-to-Grid) Deployment – allow electric vehicles to act as batteries, absorbing or injecting energy according to system signals.
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