On January 14, 2026, FERC accepted the Southwest Power Pool, Inc.’s (SPP) revisions to its Open Access Transmission Tariff (Tariff) to create a High Impact Large Load (HILL) study process and High Impact Large Load Generation Assessment (HILLGA) process. The HILL study process establishes study and operational requirements for HILLs connecting to SPP’s transmission system. The HILLGA is a new interconnection process for interconnection requests of generation resources necessary to serve HILLs. The Tariff revisions are effective as of January 15, 2026.
Before the reforms were approved by FERC, SPP would evaluate a transmission customer’s request to modify or add delivery point facilities by studying the impacts of the request on SPP’s transmission systems and determine if additional network upgrades are necessary to complete the request. SPP’s generator interconnection procedures consist of a two-part system impact study and an interconnection facilities study.
On October 24, 2025, SPP proposed to: 1) establish a HILL study process that includes study requirements and operational requirements for any HILLs seeking to interconnect to SPP’s transmission system; and 2) create the HILLGA, an optional interconnection process (with stringent eligibility requirements) designed to both study generation resources seeking to serve a HILL and determine if any network upgrades are required. SPP also proposed to define HILLs as load either 1) above 10 MW if connecting at less than or equal to 69 kilovolts (kV); or 2) 50 MW or more if connected at or above 69 kV. SPP argued that the HILL study process and HILLGA were necessary to serve an unprecedented surge in interconnection of HILLs, which are both energy intensive and pose reliability challenges. In support of these changes, SPP argued that nearly 6 GW of HILLs requested interconnection to SPP’s transmission system in 2024.
FERC found SPP’s proposed HILL study process to be just and reasonable. In particular, FERC found SPP’s allocation of study deposits and study costs satisfied FERC’s cost causation principle. FERC also accepted SPP’s proposed ongoing reliability requirements for HILLs and found that the HILL study process will ensure reliable operation of SPP’s transmission system.
FERC also found the HILLGA to be just and reasonable, finding that SPP’s proposed interconnection process will ensure timely and efficient interconnection of generation resources necessary to serve HILLs. FERC determined the HILLGA’s eligibility requirements will deter speculative interconnection requests and ensure limited impacts on SPP’s transmission system.
FERC also directed SPP to file a compliance filing designed to correct ministerial errors. Commissioner Rosner filed a concurrence, stating that SPP’s Tariff revisions will support economic growth within the SPP footprint and inviting other transmission providers to file similar proposals.
FERC, in a separate order issued on January 22, 2026, declined requests for rehearing on SPP’s Tariff revisions to implement SPP’s proposed Expedited Resource Adequacy Study (ERAS) process, which created an expedited study framework for studying interconnection requests addressing near-term resource adequacy needs. SPP’s ERAS process, similar to the HILL study and HILLGA proposals, involves a voluntary interconnection process designed to ensure SPP can serve increasing load growth. SPP argues the ERAS process is a condensed timeframe interconnection review process designed to expedite interconnection of “shovel-ready” projects that will help maintain resource adequacy in SPP’s system. On rehearing, FERC upheld its acceptance of SPP’s ERAS process.
FERC’s Order accepting SPP’s HILL study process and HILLGA, issued in Docket No. ER26-247-000, is available here. FERC’s Order declining requests for rehearing on SPP’s ERAS process, issued in Docket No. ER25-2296-002, is available here.