Brazil's Grid Operator ONS Curtails Excess Renewable Power to Stabilize System

On 7 June, Brazil's Operador Nacional do Sistema Elétrico (ONS) activated an emergency curtailment plan to reduce the amount of electricity entering the national grid. The measure, applied for the first time since the plan was approved in November, targeted generation from wind and solar farms to prevent frequency imbalances caused by an unprecedented surplus of renewable output combined with lower demand during a long Corpus Christi holiday and cooler temperatures.

ONS described the action as an “exceptional” step to control system frequency. The curtailment follows a shift in Brazil’s generation mix, with distributed solar installations now representing about 5 % of all consumers—roughly 4.5 million households and businesses—who can feed electricity back into the grid. Analysts such as Joisa Dutra of Fundação Getúlio Vargas warned that the grid must keep supply and demand closely matched, and the current excess highlights the challenges of integrating large‑scale renewable sources.

The emergency reduction aims to maintain grid stability while the country adapts to a more diversified energy portfolio that includes significant wind and solar capacity alongside traditional hydro, thermal and nuclear plants.