PVTIME – Despite ongoing grid expansion initiatives, Spain continues to grapple with persistent grid bottlenecks, with uncompensated solar curtailment expected to remain elevated until 2027. According to global power market analysis firm Aurora Energy Research, uncompensated curtailment volumes are expected to reach 3.05TWh in 2026, rising to 3.38TWh in 2027. This reflects a structural challenge that will be difficult to reverse in the short term.
The country’s renewable energy experienced a record-breaking amount of uncompensated curtailment in 2025, with volumes doubling compared to the previous year. July accounted for around a third of the annual total, which coincided with peak solar generation output. Curtailment rates peaked at 11% in summer, with around 892GWh of renewable energy generation being reduced due to grid constraints.
Following a power outage in April 2025, Spain’s power system operations have been subject to comprehensive tightening. Grid operator Red Eléctrica has enhanced safety standards and implemented upgraded operational models, leading to increased reliance on technical constraints and ancillary services. This shift has driven a 49% year-on-year rise in system operation costs, reaching €3.77 billion (approximately $4.4 billion).
Aurora Energy Research has modelled Spain’s curtailment trends over the next decade, taking into account regional grid bottlenecks and zonal dispatch characteristics. The analysis confirms that solar energy will be the primary source of uncompensated curtailment, accounting for an estimated 2.5% of Spain’s total electricity generation in 2026. The issue is also geographically widespread, with significant variations in curtailment levels across different connection nodes and regions.
Curtailment rates differ markedly between individual nodes. For example, the most severely affected node in Badajoz province could see a curtailment rate of 22.5%, whereas another node in the same province is likely to experience a rate of just 3.55%. Badajoz is projected to account for 20% of national uncompensated curtailment in the short term, followed by Zaragoza and Cáceres. Aurora Energy Research notes that grid congestion patterns are dynamic and will evolve alongside grid upgrades, dispatch adjustments, and the commissioning of new generation capacity.
Annual uncompensated curtailment is expected to remain at around 3TWh until 2027. This persistent issue directly impairs market operational efficiency and poses challenges to the financing viability of both merchant and power purchase agreement projects. Aurora Energy Research indicates that, provided grid expansion accelerates, energy storage deployment is expedited and electricity demand grows through industrial electrification and renewable hydrogen initiatives, curtailment pressures could begin to ease after 2028.
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