The Federal Energy Regulatory Commission (FERC) approved the Southwest Power Pool’s (SPP) proposal to provide non-firm transmission service to data centers and other large industrial loads that agree to accept curtailment during grid emergencies. The new service, formally designated the Conditional High Impact Large Load Service (CHILLS), establishes a structured, time-limited bridge to firm transmission access for high-demand customers whose dedicated generation resources or required network upgrades are not yet in service.
The decision represents the latest step in a broader series of regulatory reforms that SPP and FERC have been advancing since mid-2025. It also represents one of the most operationally concrete federal responses to date to the challenge of rapidly integrating large commercial and industrial loads into a regional grid operating at or near capacity.
What CHILLS Is and How It Works
Under CHILLS, SPP will provide transmission service using available uncommitted transmission capacity for up to seven years. Eligible customers must qualify as High Impact Large Loads (HILLs), defined as loads of 50 megawatts or greater connected at voltages above 69 kilovolts or loads of 10 megawatts or greater connected at 69 kilovolts or below. The service is available only to HILLs and is not accessible to critical loads, which continue to follow separate interconnection and service pathways.
CHILLS is classified as a non-firm, conditional service. In the SPP tariff priority hierarchy, it holds equal standing with the monthly non-firm point-to-point transmission service. But ranks below native load, Network Integration Transmission Service (NITS), long-term firm service, and short-term firm service. As a result, CHILLS is subject to curtailment when SPP declares a grid emergency or experiences other unforeseen system conditions that require relief. Large loads accepting CHILLS service assume that curtailment risk as a condition of obtaining accelerated grid access.
Any upgrades identified as necessary to maintain system reliability must be identified through the applicable study processes and assigned to the responsible party. This approach insulates the broader transmission system from cost allocation exposure tied to conditional service arrangements.
The Regulatory Sequence That Led to June 5
The CHILLS approval did not arise in isolation. It is the fourth in a sequence of interconnected regulatory actions through which SPP has systematically restructured its approach to large-load interconnection.
The first action was FERC’s acceptance of SPP’s Provisional Load Process, effective August 4, 2025. That revision to SPP’s Open Access Transmission Tariff (OATT) authorized SPP to evaluate new load interconnection requests even when a transmission customer does not yet have sufficient generation to cover its projected 10-year load forecast. Previously, SPP was unable to proceed with study work on many large-load requests because applicants lacked a committed power supply. The Provisional Load Process (PLP) removed that structural barrier to initiating study activity.
The second action followed on January 14, 2026, when FERC unanimously approved SPP’s High Impact Large Load (HILL) study process and the associated High Impact Large Load Generation Assessment (HILLGA) process. The HILLGA created an accelerated interconnection pathway for generating facilities whose output is designated exclusively to serve a co-located HILL in the same local area. Under this framework, SPP targets completion of coordinated interconnection studies for both the new generation and its associated load within 90 days. The Load Limited Resource Interconnection Service (LLRIS), which grants limited interconnection to generation serving a local HILL, was established simultaneously with the LLRIS generator interconnection agreements, which are set to terminate automatically five years after service initiation.
The third action was FERC’s March 13, 2026, approval of SPP’s Consolidated Planning Process (CPP), a comprehensive overhaul that merged SPP’s previously separate generator interconnection and transmission planning tracks into a single, proactive three-year planning cycle. In approving the CPP, FERC characterized the proposal as a potential national template for interconnection reform.
CHILLS, the fourth action, completes a sequentially constructed regulatory framework. Together with the Provisional Load Process (PLP), the HILLGA, and the CPP, CHILLS gives SPP a coherent, end-to-end process for receiving, studying, interconnecting, and providing transmission service to large loads, from initial application through to long-term firm service. SPP refiled the CHILLS tariff revisions on February 10, 2026, following earlier stakeholder process considerations and requested an effective date of July 1, 2026.
Conditions, Constraints, and What CHILLS Does Not Provide
The CHILLS approval is appropriately understood as a calibrated accommodation rather than an unconditional grant of grid access. Several structural constraints define its scope and limit its application.
CHILLS is explicitly non-firm. Customers receiving CHILLS service must accept, as a condition of eligibility, that SPP retains full authority to curtail their service during declared emergencies or under conditions that require operational relief. The service carries no reliability guarantee equivalent to that afforded to firm transmission customers, and no financial exposure is shifted to the broader transmission system or its ratepayers to protect CHILLS service continuity.
Customers who do not complete a firm service pathway within the bridge period will not retain CHILLS eligibility on an ongoing basis. The structure is designed to prevent the conditional service from functioning as a permanent substitute for firm interconnection.
Significance for Large Load Developers
For data center developers and large industrial customers seeking grid access in the SPP footprint, the CHILLS approval creates a demonstrably faster path to energization than previously available. Where dedicated generation resources are under development and network upgrades have been identified but not yet constructed, a load customer can now request CHILLS service, complete the associated study process targeting a 90-day timeline under the HILLGA framework, and obtain conditional transmission service, provided it accepts the curtailment obligations.
The sequential construction of SPP’s large load integration framework, as recognized by FERC in its March and June 2026 orders, reflects a regulatory approach that other regional transmission organizations are closely monitoring. FERC has encouraged RTOs across its jurisdiction to examine SPP’s consolidated model as a potential template. Whether and how MISO, PJM, and other grid operators adopt analogous structures will be a defining question in large load interconnection policy over the coming planning cycles.
Conclusion
FERC’s June 5, 2026, approval of CHILLS completes the final component of SPP’s restructured large-load interconnection framework. The combination of the Provisional Load Process (PLP), the HILLGA 90-day study pathway, the Consolidated Planning Process (CPP), and CHILLS now provides SPP with a sequentially coherent set of tools for managing the integration of high-impact, large loads into a grid operating under intensifying demand pressure.
The conditional, non-firm character of CHILLS service preserves system reliability and the integrity of cost allocation while providing a structured bridge to firm service for customers whose long-term interconnection is in progress. The regulatory outcome represents a measured and legally grounded response to one of the most consequential operational challenges facing the U.S. electric grid in 2026.
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Disclaimer: Any opinions expressed in this blog do not necessarily reflect the opinions of Certrec. This content is meant for informational purposes only.
