Spain's “curtailment” Rate Hits A New Record High

Recently, global power market analysis firm Aurora Energy Research noted that although Spain’s grid expansion plans are underway, ongoing grid bottlenecks will continue to constrain the country’s grid, resulting in persistently high levels of curtailed solar power in 2026–2027. Curtailed solar power is projected to reach 3.05 TWh in 2026 and rise to 3.38 TWh in 2027.

In 2025, Spain’s curtailed renewable energy generation reached a record high, doubling from the previous year. In July alone—coinciding with the peak period for solar power output—curtailment accounted for approximately one-third of the annual total. The curtailment rate peaked at 11% during the summer, with approximately 892 GWh of renewable energy generation forced to be curtailed due to grid bottlenecks.

Notably, following the power outage in April 2025, operational controls over Spain’s power system were significantly tightened. The Spanish grid operator, Red Eléctrica, raised safety standards and adopted enhanced operational modes, significantly increasing reliance on technical constraints and ancillary services. This led to a 49% year-over-year surge in system operating costs, reaching 3.77 billion euros (approximately $4.4 billion).

Aurora Energy Research simulated Spain’s curtailment trends for the next decade by integrating regional grid bottlenecks with the characteristics of zonal dispatch. The analysis indicates that uncompensated curtailment will remain at 3.05 TWh in 2026 and reach 3.38 TWh in 2027, with the structurally high curtailment pattern proving difficult to reverse. Photovoltaic (PV) power is the primary source of curtailed generation; in 2026, PV curtailment is projected to account for 2.5% of the country’s total electricity generation, with the phenomenon exhibiting a widespread geographic distribution.

Curtailment rates vary significantly across grid nodes: the most severely affected node in Badajoz Province could see a curtailment rate as high as 22.5%, while another node in the same province would see only 3.55%. Regionally, Badajoz is projected to account for 20% of the nation’s total short-term curtailment, followed by Zaragoza and Cáceres. Aurora Energy Research also notes that grid congestion patterns are not static and will evolve dynamically with grid upgrades, dispatch adjustments, and the commissioning of new capacity.

Until 2027, the annual average curtailment volume is expected to remain around 3 TWh, directly impacting market operational efficiency and posing challenges to the bankability of market-based projects and Power Purchase Agreements (PPAs). If grid expansion accelerates, energy storage installations are rolled out more quickly, and electricity demand continues to grow from industrial electrification and renewable hydrogen, Spain’s curtailment pressure is expected to gradually ease after 2028.