SPP's Answer to the Data Center Queue: Connect Now, Accept Interruption, Go Firm Within Seven Years

Southwest Power Pool has quietly built the most complete set of large load rules of any US grid operator. In January the Federal Energy Regulatory Commission accepted SPP's High Impact Large Load study process, known as HILL, and the companion High Impact Large Load Generation Assessment, or HILLGA. On June 5 it approved a further piece, the Conditional High Impact Large Load Service, which SPP calls CHILLS. Together they give data centers in SPP's 17-state footprint, which runs from northern Texas to Montana, a path that trades guaranteed delivery for speed.

SPP's filing, summarized in FERC's January 14 order, sets out why the existing processes failed large loads. Requests from customers above 100 MW peaked in 2022 at nearly 11 GW, then fell to about 6 GW in 2024. SPP submitted the HILL and HILLGA tariff revisions on October 24, 2025, and FERC accepted them effective January 15, 2026, subject to a compliance filing within 30 days. The design pairs a new large load with shovel-ready generation and studies them together, rather than forcing the load through the delivery point process and the generator through the general interconnection queue separately.

Commissioner Rosner's concurrence describes the central innovation as a new interconnection service, Load Limited Resource Interconnection Service, which limits the amount of output the paired generator can inject to what the grid can handle given the associated load. He wrote that the combined processes would allow paired generation and load to connect in less than half the time typically required to clear SPP's generator interconnection queue. HILL and HILLGA speed things up, but they still require generation and network upgrades to be in place before a large load gets firm service.

FERC's June 18 show cause orders asked every RTO and ISO to address, among other things, new transmission services for flexible large loads and processes to study generation serving co-located or electrically proximate loads.