An Overdose of Renewables, New Energy Risk in Brazil

By Mario Osava
RIO DE JANEIRO, Sep 25 2025 – Wind and solar power sources, essential for the energy transition to mitigate the climate crisis, have become a risk of power outages in Brazil.

It is a remedy that, in excess, becomes poison. The rapid and unplanned growth of these alternatives has created operational difficulties for the Brazilian electricity system, which is nationally interconnected.“Brazil has one of the most complex electricity systems in the world. No other country has such a diversity of sources”–Luiz Barata.

A blackout on August 15, 2023, which affected 27% of the supply throughout most of the country, was a major wake-up call about insecurity. It began with the transmission of wind and solar power plants in the state of Ceará, in northeastern Brazil.

It almost happened again in April and August of this year due to excess generation, according to the  National System Operator (ONS), a private organization that represents consumers and all sectors involved, which coordinates and controls supply nationwide.

A functional electrical system requires surpluses; energy must be available at all outlets for eventual consumption. But “too much excess causes problems,” said Luiz Barata, former director general of the ONS and current president of the non-governmental National Front of Energy Consumers.

The proliferation of solar and wind power plants in Brazil has created imbalances between supply and consumption that caused operational difficulties in effective distribution, such as power outages in 25 of Brazil’s 26 states on August 15, 2023. Credit: Fotos Públicas

Renewables in question

The intermittent nature of wind and solar power, which have grown the most in the last decade, exacerbates the risks due to their uncontrollable origin. This type of energy depends on nature, on when there is wind and sun.

The plot thickens with distributed generation, also known as decentralized generation, which turns consumers into producers of their own electricity in 3.8 million residential micro-plants or groups of individuals or small businesses.

This dispersed generation already exceeds 43 gigawatts of power, according to data from the National Electric Energy Agency (Aneel), the sector’s regulatory body.

This amounts to 18% of the country’s total generating capacity, with solar photovoltaic power dominating the segment with a 95% share.

“In addition to being uncontrollable, because it depends on the sun, distributed generation cannot be interrupted, as it is beyond the control of the ONS,” warned Barata, an electrical engineer.

What the ONS does is curtail the contribution of some generating sources when excess supply threatens the system. In general, the interruption affects wind and solar generation, which are further away from the area of highest consumption.

The Northeast, favored by strong and regular winds and solar radiation, concentrates most of these sources, while the highest electricity consumption occurs in the Southeast, Brazil’s most populous and industrialized region.

Wind farms occupy hills and mountains throughout the Northeast region of Brazil, which has become a supplier of electricity for the entire country. The intermittency of this source, with generation concentrated at night, contributed to the risk of blackouts in the country. Credit: Mario Osava / IPS

Uncertain future

The trend is for operational problems in the electricity system to worsen because distributed generation continues to expand, due to the legal incentives it enjoys, and without planning, as it is the result of individual decisions.

From January to August 2025, the ONS discarded 17.2% of the country’s potential wind and solar generation, which corresponds to 7% of the country’s monthly consumption. This tripled the cuts compared to the same period in 2024, according to an analysis by Volt Robotics, an energy consulting firm.

In August, the rejection reached 57% of new renewable generation due to excess supply.

“Brazil has one of the most complex electricity systems in the world. No other country has the diversity of sources that we have,” Barata told IPS by telephone from Brasilia.

Of a total of 236 gigawatts of installed capacity at the end of 2024, hydroelectricity continues to account for a majority, with 46.5% of the total, according to the state-owned Energy Research Company. But it is no longer as dominant as it was in 2000, when it accounted for 89%.

Solar energy, with 20.5%, wind energy with 12.5% and thermal energy, which consumes fossil fuels and biomass, with 18.6%, already exceeded hydroelectricity in 2024, with a trend towards further growth.

Necessary reform

There has been a change in the electricity matrix, which has shifted from hydrothermal, basically hydroelectric and supplemented by thermal power plants, to a growing incorporation of new renewable sources, given the lower cost of their implementation and distributed generation, Barata pointed out.

However, legislation and regulations have not kept pace with this transformation, said the expert, who believes the sector needs a comprehensive structural reform in order to reduce risks and restore better operating and planning conditions.

“It is a complex system that cannot be solved with simple measures,” he said.

Joilson Costa, coordinator of the non-governmental Front for a New Energy Policy for Brazil and also an electrical engineer, considers it “incorrect” to attribute systemic risks solely to excess wind and solar generation.

“Excess supply is only part of the problem, not the only one. Another cause is the deficiency of the transmission system, which makes it impossible to transport the energy generated in the Northeast to other regions at certain times. This then necessitates a cut in generation,” he argued.

Nor can it be said that distributed generation is outside the scope of planning. The Energy Research Company, part of the Ministry of Mines and Energy, does consider this modality in its plans because “its studies and simulations allow it to make estimates,” even though it cannot control the expansion of microplants, Costa noted.

Electricity distribution companies also monitor the evolution of distributed generation in their networks and can update their data monthly, he told IPS by telephone from São Luis, capital of the northeastern state of Maranhão.

Distributed generation, which is small-scale and generally consists of photovoltaic panels on residential or commercial roofs, already accounts for 43 gigawatts of installed capacity in Brazil. There are 3.8 million plants benefiting seven million consumer units, without the necessary control over the operation of the national electricity system. Credit: Mario Osava / IPS

Daily asynchrony

The major risk factor, however, is the lack of synchrony between the generation and consumption of new sources of electricity in their daily cycles.

Solar generation occurs during the day, peaking around noon, when consumption is low. It declines just as consumption increases at the end of the day and beginning of the night, when lights and household appliances are turned on, especially electric showers, which are widely used in Brazil.

Wind farms, concentrated in the Northeast, generate electricity mainly late at night, when consumption drops again.

Pericles Pinheiro, director of New Business at CHP, a gas generation equipment and solutions company in Rio de Janeiro, identifies a trend toward crisis in the Brazilian electricity system in his ongoing analysis of the sector. “Every summer, new emotions,” he jokes.

In previous years, he identified a risk in the proliferation of diesel generators that many companies used to avoid the higher cost of electricity during peak consumption hours in the early evening.

But they abandoned this resource because they migrated to the free market, which has expanded in Brazil in recent years, lowering energy costs for large consumers by allowing them to choose their supplier.

Diesel generators, which helped reduce the upward curve of consumption during peak hours, disappeared or declined, exacerbating daily fluctuations in demand, in cycles opposite to those of wind and solar sources, Pinheiro told IPS.

Distributed generation reduces demand on the grid and the share of electricity managed by the system operator, in a trend that exacerbates insecurity, he added.

The ONS estimates that by 2029 it will control less than half of the country’s installed generation capacity, increasing the operational uncertainty of the national interconnected system.

The proliferation of digital data centers in Brazil, which the government is trying to promote, is seen as a way to balance electricity consumption and supply in the country.

But these huge energy sinks would consume the excess during the day but increase demand at night, as they operate 24 hours a day, warned Pinheiro, who identifies another risk in electric vehicles whose batteries consume the electricity of several homes when recharging.