SPP BESS Buildout 2026 Q2: Queue transition streamlines fleet to 1.4 GW
In 2026 Q2, SPP saw eight batteries totaling 820 MW reach their stated commercial operation dates, lifting the battery fleet to 1.4 GW across 15 projects.
The region's 53 GW battery queue remains the third largest in the US. Meanwhile, the first transition cycle of SPP's Consolidated Planning Process (CPP) is now underway. The reform is reshaping how congested clusters from previous years move through the queue.
This report examines which batteries reached commercial operation, what the near-term pipeline holds, and what's driving the updated buildout projection through 2031.
Read last quarter’s report here.
Key takeaways
- 820 MW across eight projects reached their stated commercial operation dates in Q2 2026, the largest quarterly total in SPP's history, up from 252 MW in our previous update. Only the 36 MW Cunningham project has so far appeared in EIA-860M operational data.
- 1.3 GW of IA-agreed capacity targets commercial operation between Q3 2026 and Q1 2027, concentrated in Q4 2026. The 594 MW GREC replacement is the single largest project in the near-term pipeline.
- 65% of battery capacity in the queue is co-located. Solar co-location leads at 24.5 GW, followed by wind at 5.9 GW.
- Updated buildout projections reaches 21 GW by 2031. Completion rates are now measured from SPP's own queue history, then extended with Modo's economic capacity expansion forecast.
Eight projects raise SPP battery capacity by 820 MW
Eight battery projects with stated commercial operation dates in Q2 2026 total 820 MW.
NextEra’s Hitchland (200 MW, Gruver, Texas) is the largest site added this quarter.
A note on methodology
Generators in the queue with an executed interconnection agreement flagged as “ON SCHEDULE” are marked as commercially operational once their expected COD have passed.
This assumption assumes SPP delays updates to its queue database.
Press releases and EIA datasets are used to corroborate projects’ online status. Projects are assumed to still be in development if their stated COD has past and there is evidence of an updated future operational date.
The next largest are Drumtown Solar (177 MW, Drumright, Oklahoma) and two 100 MW projects: Brown (Twelvemile Solar, Johnston County) and Mustang (Colt Grid, Canadian County).
These additions lift SPP's battery fleet to 1.4 GW across 15 projects.
The fleet remains concentrated in Oklahoma, and NextEra is the dominant developer.
1.3 GW of battery capacity targets commercial operation by Q1 2027
Beyond the Q2 additions, seven battery projects with signed Generator Interconnection Agreements (GIAs) target commercial operation between Q3 2026 and Q1 2027. Together they total 1.3 GW.
Activity concentrates in Q4 2026, which accounts for 1,111 MW across five projects. The largest is the 594 MW GREC BESS plus Gas replacement for Grand River Dam Authority in Chouteau, Oklahoma, the single largest project in the near-term pipeline.
It is joined by NextEra's 220 MW White Tail (Surplus), the 152 MW Buffalo Flats (DISIS-2017), the 125 MW Ault-Carey project (RTOE Transitional Cluster), and Invenergy's 20 MW Post Rock.
A further 184 MW targets Q1 2027: Liberty West (100 MW, DISIS-2022), Fly Gap Solar (73 MW, Surplus), and Osborne Grid's 12 MW Jones Street project.
Surplus cohorts are driving 11.8 GW of co-located battery capacity across 73 projects in SPP
The Surplus Interconnection Process remains the fastest route to market for battery developers in SPP.
73 active battery projects totaling 11.8 GW sit in the Surplus queue, up from 56 projects and 8 GW in the previous update.
All Surplus batteries co-locate with existing generation. They connect at the Point of Interconnection of an operational wind, solar, or thermal plant. Surplus projects split between wind (32 projects, 5.6 GW) and solar (27 projects, 4.4 GW).
The streamlined Surplus process, coupled with hybrid solar-plus-storage entries in the traditional clusters, means co-located batteries now account for 65% of SPP's active battery queue. Solar co-location leads at 24.5 GW across 122 projects, followed by wind at 5.9 GW and thermal at 2.1 GW.
The Surplus pipeline is progressing: five batteries have reached commercial operation, 17 are have signed interconnection agreements, and 51 remain active earlier in the process.
Historically, 21 of 94 Surplus battery projects have withdrawn, a 78% retention rate. This is well above the DISIS queue, where attrition exceeds 50% in most cohorts. The lower attrition reflects the pathway's key advantage: no new transmission upgrades are required, removing the main source of cost uncertainty that drives DISIS withdrawals.
SPP ERAS holds 2.5 GW via the expedited pathway
SPP's Expedited Resource Adequacy Study (ERAS) program accelerates interconnection for projects that can help address near-term resource adequacy shortfalls. 11 battery and hybrid projects totaling 2.5 GW are in ERAS, with no withdrawals to date.
The majority are hybrids, reflecting developers' preference for co-located configurations. Projects cluster in the Southwest and Central regions, with commercial operation dates spread between 2027 and 2030.
5 GW more batteries receive interconnection agreements in Q2, as CPP unblocks the queue
With the CPP transition to a streamlined interconnection process, over 5 GW of additional battery projects have signed interconnection agreements since last quarter.
Batteries with interconnection agreements now make up a majority of projects in the pipeline: 16.3 GW across 102 projects. DISIS holds 15.7 GW, still the deepest early-stage pool with the highest attrition risk.
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