Brazil’s National Electric System Operator (ONS) projects renewable energy curtailment at wind and solar plants could reach up to 40 GW per year between 2027 and 2030, reflecting growing renewable generation surpluses during parts of the day and operational constraints across the country’s interconnected power system.
According to the executive summary of the operator’s Medium-Term Electric Operation Plan (PAR/PEL) 2025 for the 2026-2030 period, curtailment will remain concentrated during hours of peak solar generation, when high photovoltaic output, lower electricity demand and transmission constraints require renewable generation to be reduced to maintain system security and reliability. Curtailment is expected to be significantly lower at night, highlighting the challenge created by the daily generation profile of solar power.
The study indicates the issue will persist throughout the planning horizon, even with projected growth in electricity demand. In a sensitivity analysis, ONS evaluated the addition of 4 GW of new loads to the system and found it would reduce curtailment by less than 800 MW on average, a result the operator considers insufficient given the scale of the projected surplus.
ONS said reducing curtailment will require a combination of structural measures, including transmission expansion, deployment of BESS, demand response programs, greater operational flexibility and new electricity consumers capable of absorbing surplus renewable generation during daylight hours.
The report adds that none of these measures alone will eliminate the problem. According to ONS, continued expansion of variable renewable generation must be matched by demand growth, particularly during daytime hours. If utility-scale solar generation and distributed generation continue to grow faster than electricity consumption, the system could face an increasingly large structural surplus, requiring more operational restrictions.
The operator said integrated planning across generation, transmission and electricity demand will be essential, arguing that the challenge is not only to expand renewable generation but also to ensure the electricity produced can be effectively used by the power system.
The PAR/PEL also outlines investments in transmission infrastructure to increase the capacity to deliver renewable electricity. The plan includes approximately 5,301 km of new transmission lines, 24,314 MVA of transformer capacity and BRL 28.1 billion ($5.4 billion) of investment over the planning period.
Among the key projects is an increase in transmission capacity between Brazil’s North/Northeast and Southeast/Central-West regions from 18.5 GW in January 2026 to 23 GW by 2030, allowing more renewable electricity generated primarily in the Northeast to reach the country’s main demand centers.
ONS projects peak demand across the National Interconnected System (SIN) will reach about 129 GW by 2030, representing an increase of about 17% compared with the 2025 peak. Over the same period, installed generation capacity is expected to reach 269 GW, driven by continued renewable energy expansion.
Installed utility-scale wind and solar capacity is projected to reach about 60 GW by the end of the planning horizon. Including all projects that have already signed transmission system use agreements (CUST), that figure could reach approximately 77 GW, further increasing the need for system flexibility.
The operator said the growing share of renewable energy will require additional operational tools to preserve grid reliability, including resources capable of providing flexibility, operating reserves and grid stability services.
The report also highlights the role of distributed generation in reshaping Brazil’s electricity demand profile. According to ONS, distributed generation now exceeds 43 GW of installed capacity, reducing daytime grid demand, increasing evening demand ramps and creating reverse power flows across parts of the distribution network.
Despite these operational challenges, ONS said distributed energy resources could help improve system flexibility when combined with smart management and operational control. Current initiatives include updates to Brazil’s electricity distribution procedures (PRODIST), an energy surplus management plan for distribution networks and improvements to how distributed generation is represented in the operator’s planning models.
From pv magazine Brazil
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