SPP Sets 36% Winter Planning Reserve Margin

Southwest Power Pool (SPP) has set a 36% Winter Planning Reserve Margin (PRM) for the 2026-27 capacity season, while the Summer PRM will be 16%. This change affects load-serving entities in the SPP region, which includes parts of Arkansas, Iowa, Kansas, Louisiana, Minnesota, Missouri, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, and Wyoming. The new PRM values take effect for the 2026-27 capacity season, starting on June 1, 2026. According to SPP, the reference CONE has also increased to $139.85/kW-year from $85.61. As reported by SPP on March 12, 2026, these changes are part of the organization’s seasonal Resource Adequacy (RA) framework.

What Changed

The significant increase in Winter PRM to 36% and the rise in Summer PRM to 16% mark a major shift in SPP’s RA framework. This change is notable, as it represents the largest seasonal divergence in U.S. RTO history. The reference CONE, which climbed to $139.85/kW-year, is also a key factor in this change. As explained by CES Ltd on April 2, 2026, the capacity gap in SPP is a critical issue that needs to be addressed. The Effective Load Carrying Capability (ELCC) accreditation method will continue to be used to ensure that resources meet the required standards.

Why It Matters

The new PRM values and reference CONE will have a significant impact on load-serving entities in the SPP region. These entities will need to secure sufficient capacity to meet the increased PRM requirements through bilateral contracting, backed by ELCC-accredited resources. As noted by Modo Energy on April 10, 2026, understanding the SPP resource adequacy framework is crucial for market participants. The changes to the PRM values and reference CONE will require load-serving entities to reassess their capacity needs and adjust their contracting strategies accordingly.

Critical Perspective

The significant increase in Winter PRM to 36% raises questions about the potential impact on the market and the ability of load-serving entities to secure sufficient capacity. According to CES Ltd, the capacity gap in SPP is a pressing concern that needs to be addressed. The use of ELCC-accredited resources will be critical in ensuring that the required capacity is met. As the 2026-27 capacity season approaches, market participants will be closely watching the developments in the SPP region to understand the implications of these changes. SPP’s decision to increase the Winter PRM to 36% will be closely scrutinized, and its impact on the market will be carefully monitored by regulators, market participants, and load-serving entities.

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