​Battery development in the Southwest Power Pool (SPP) has been limited to date, despite leading the U.S. in wind penetration. However, the region is poised to see a change in the coming years.

53 GW of battery capacity is in the queue today, and retiring thermal generation, rising demand, and continued renewable growth will drive the need for storage to come online.

Executive Summary

• 10.7 GW of battery storage is expected to reach commercial operation by 2030. This represents just 20% of SPP’s total queued BESS capacity. The projection reflects stage-weighted completion rates and regional development timelines.
• Queued batteries average four hours of duration, reflecting developers’ focus on maximizing revenues in SPP’s bilateral Resource Adequacy market. Four-hour assets are best aligned with evening peak coverage and accreditation rules.
• SPP’s interconnection queue exceeds 150 GW of total generation capacity. The operator now runs an annual Cluster Study cycle and a streamlined Surplus Interconnection process that enables faster approvals for hybrid and co-located projects.
• Storage growth is driven by retiring thermal capacity (3.6 GW by 2030), rising peak demand (+14% by 2030), and high renewable penetration. Wind already provides around 40% of annual generation, and large-scale solar additions are accelerating.

​Batteries, solar, and wind dominate the SPP interconnection queue

The latest SPP interconnection data shows developers are overwhelmingly focusing on renewables and storage. This reveals how quickly the region’s generation mix is shifting toward flexibility and clean capacity.

​Renewables drive the queue, with solar and wind together making up nearly half of all queued capacity, with more than 75 GW tentatively scheduled to reach commercial operations by 2030.

Batteries follow, with over 50 GW of BESS capacity queued across SPP. Standalone projects lead early years, but co-located projects combining solar or wind with storage - listed as “hybrids” in SPP’s queue, though not necessarily DC-coupled - are projected to rise sharply after 2027.

Thermal projects make up less than one quarter of SPP’s queued capacity. This is a clear sign that developers are prioritizing renewables and storage. The shift reflects both higher capital costs and longer development timelines - including longer procurement lead times - for new thermal generation. This helps clean energy projects be more competitive in today’s market.

Only 300 MW of batteries are operating, but the interconnection queue exceeds 50 GW

SPP’s BESS buildout concentrates toward the late 2020s, with 2028 and 2029 marking the highest buildout years. Of the total queued capacity, 60% of projects are labeled as standalone BESS. Meanwhile, 39% are hybrids paired with solar, and 1% hybrids paired with wind.

​SPP’s Surplus Cluster allows developers to reuse existing interconnection capacity by adding new generation or storage to existing wind or solar sites. The program was introduced to make better use of underutilized grid capacity at existing points of interconnection. This reduces study times and costs for projects that can share infrastructure.

Around 3.3 GW of planned storage tagged as standalone sit within this cluster. Adjusting for these surplus projects, the true standalone share of SPP’s BESS queue falls to roughly 54%.

This highlights a key trend: hybrid projects in the Surplus cluster are gaining strategic ground, offering developers faster interconnection pathways compared to new builds.

12% of BESS projects in the interconnection queue are in late-stage development

​SPP currently has 6.2 GW of late-stage storage projects, those with a fully executed Generation Interconnection Agreement (GIA). These are the projects most likely to proceed to construction in the near term.

A further 10.3 GW are in mid-stage development, which means they are advancing through the Facility Study or have a pending GIA.

The remaining 36.2 GW of capacity are still in early-stage studies (Expedited Resource Adequacy Study (ERAS) or Definitive Interconnection System Impact Study (DISIS) phases), with most targeting commercial operation between 2028 and 2030. ​

To understand how much of this pipeline could realistically reach Commercial Operation, stage-specific completion rates are applied to estimate SPP’s achievable BESS buildout.

SPP BESS buildout is expected to reach 10.7 GW by 2030