Brazil wasted 20,6% of all available solar and wind energy by 2025, according to a survey by Volt Robotics.
The data highlights a growing bottleneck in the national electricity sector: the system's difficulty in efficiently absorbing the rapid expansion of renewable energy sources.
In economic terms, the study indicates that the unused energy represented a loss of over R$ 6 billion during the period.
The impact goes beyond direct financial losses, affecting the predictability of projects, putting pressure on generators' revenues, and increasing the perceived risk for new investments in clean energy in the country.
According to the analysis, the problem intensified between August and October, a period marked by three consecutive record-breaking generation cuts, known as curtailment.
During this period, the combination of high supply, limitations in transmission infrastructure, and operational restrictions led to the forced shutdown of power plants, even with abundant natural resources.
The peak occurred in October, when the average volume of power cut reached approximately 8.000 MW.
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Monthly evolution of cuts since October 2021, with consecutive historical records of cuts in the months of August, September, and October 2025. Source: Volt Robotics
The study shows that after reaching critical levels in the third quarter, the volume of generation cuts began to decline in November, indicating a temporary inflection in the behavior of the electrical system.
According to the study, last month the cuts fell to around 4.600 MW on average, with an estimated financial impact of R$ 700 million, down from R$ 1,1 billion recorded in October.
In December, the downward trend intensified even further, with cuts falling to approximately 1.700 MW on average.
Despite the relief observed at the end of the year, the study emphasizes that the improvement is temporary. The reduction is mainly associated with the end of the wind season and the consequent natural decrease in wind power generation, and not with structural advances in the electrical system's capacity to absorb the expansion of renewable sources.
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Evolution of generation and monthly cuts throughout 2025. Source: Volt Robotics.
The analysis also shows that the generation cuts were concentrated mainly in Rio Grande do Norte, Ceará, and Minas Gerais, states with a strong presence of wind and solar power plants.
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Power outages in November, by state. Source: Volt Robotics.
According to Volt Robotics, in November 72% of the power cuts came from wind farms, while 28% came from solar plants, highlighting the significant role of wind power in the most severe curtailment events.
The graphs by power plant clusters also indicate a large disparity between groups of plants: while some clusters recorded cuts exceeding 120 MW on average, others were below 1 MW on average, indicating specific network bottlenecks and regional transmission limitations.
One of the most critical and curious points highlighted in the report is the system's behavior on Sundays, especially in the morning. With low consumption and high renewable energy supply, these days have become a true stress test for the SIN (National Interconnected System).
The study identified 16 critical days in 2025, during which more than 80% of available renewable generation was cut off during peak daytime hours.
The graph, which depicts the system's behavior on Sunday, November 16, 2025, clearly shows the mismatch between supply and demand throughout the day.
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Hourly power cut on Sunday, November 16, 2025. Source: Volt Robotics
The solid orange line represents the total availability of solar and wind power plants, which remains high during the daytime when there is greater solar incidence and good wind conditions.
The dashed green line indicates the reference generation, that is, the volume of energy that could be produced if there were no operational restrictions.
However, the graph reveals that this energy does not reach the system in its entirety. The limited generation, represented by the dashed orange line, reflects the ceiling imposed by the ONS (National System Operator).
Between 7 am and 17 pm, this limit drops significantly, reaching its lowest point around 11 am, precisely when renewable availability is highest. Actual generation, shown by the solid green line, remains below both potential and authorized generation, highlighting the need for cuts.
The gray area in the graph summarizes this phenomenon: it represents the generation cut, which corresponds to the difference between what could be generated with the available natural resources and what was actually injected into the system. During the peak morning and early afternoon hours, the cuts reach their peak, indicating a structural excess of supply relative to the system's absorption capacity.
The study warns that, in extreme scenarios, even with the near-total shutdown of centralized solar and wind power generation under the control of the ONS (National System Operator), there may still be excess energy due to distributed generation, especially solar.
Analysis of daily load shows that the holiday period further increases the risk. The expectation is for a drop of approximately 8.600 MW on average in daily consumption by the end of 2025, creating a scenario of low demand combined with high renewable supply.
Even with total shutdowns of centralized generation, there may be a structural surplus of energy, requiring emergency action from the ONS (National System Operator).
Institutional responses and the role of the consumer
Given this scenario, the report points to important institutional advances. ANEEL The National Electric Energy Agency (ANEEL) and the National System Operator (ONS) formally acknowledged the risk and approved an Emergency Plan, which includes extraordinary measures such as the possibility of shutting down power plants connected to the distribution network in extreme situations.
Another approach is the use of tariff signals, such as expanding the white tariff to large low-voltage consumers.
According to the study, voluntary adherence to this model was less than 0,1%, leading the regulator to evaluate its automatic application as a systemic security tool.
Finally, the study also highlights that the consumer's role can be part of the solution, by shifting flexible consumption such as washing machines, water heating, and electric vehicle charging to mornings and weekends, periods with a greater surplus of renewable energy.
Renewable generation curtailment: an overview of curtailment
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