Accelerating Project Opportunity: New CHILLS Tariff Revisions in SPP Provide Critical Flexibility

Last month, SPP filed proposed tariff revisions with FERC to create Conditional High Impact Large Load Service (CHILLS), requesting an effective date of July 1, 2026.  

CHILLS is designed as a non-firm, conditional bridge to Long-Term Service. Eligibility can require that:

• Supporting resources be in commercial operation, and
• Upgrades identified in the Load Connection Study be in service

While CHILLS provides critical flexibility for large load interconnections, it also includes explicit curtailment and reliability risk and maintains a firm separation from traditional transmission planning assumptions. It is an “as available” transmission service, lower in priority than native load, Network Integration Transmission Service (NITS), Long Term Point-to-Point service and Short-Term Firm service. It has equal priority to monthly Non-Firm Point to Point service.  

Due to these limitations, CHILLS can be curtailed for necessary system constraints and under emergency conditions. It is also capped with a seven-year maximum bridge period, during which the load must work through one of the Firm service pathways in the SPP tariff. After the pathway has been completed successfully, agreements will be updated.  

CHILLS is only available to High Impact Large Loads (HILLs), and not to Critical Loads. Smaller loads do not qualify unless they meet one of two HILL thresholds: 

• Greater than or equal to 10MW at an interconnection less than or equal to 69kV 
• Greater than 50MW at an interconnection higher than 69kV 

If a load does not meet these requirements, the developer must go through the normal AQ/AX processes to obtain firm or standard non-firm service and cannot request CHILLLS.  

How Does CHILLS Integrate with other SPP Planning Processes?  

CHILLS overlaps with existing SPP planning processes rather than replacing them, modifying operating assumptions but not firm planning models. The tariff language is designed to offer conditional optionality for a seven-year bridge period while a project is going through the AQ/AX load interconnection processes to obtain Firm Service.   

Attachment AQ (Studies Firm Service + Required Network Upgrades) 

If: 

• The AQ study identifies network upgrades required for firm service, including designated network resources 
• Upgrades take 4-6+ years 

Then:  

• CHILLS can serve the portion of the load that cannot be firm delivered for a seven-year maximum period 
• No Network Upgrades are built solely for CHILLS — they must be identified in the AQ process 

Attachment AX (Assumes Future Generation Resources to be Online Prior to Load)

• Under CHILLS, the resource must be in commercial operation, accredited through Attachment AX, and the supporting generation must be in operation prior to CHILLS being granted.  

HILL and High Impact Large Load Generation Assessment (HILLGA) Impacts

The HILL process will still apply to all other loads outside of the two thresholds.  

High Impact Large Load Generation Assessments (HILLGAs) allow for expedited load-limited interconnection of generation and provide Large Load Resource Interconnection Service (LLRIS), rather than Network Resource Interconnection Service (NRIS) or Energy Resource Interconnection Service (ERIS).  

Under CHILLLS, the HILLGA generation can be the supporting generator, but must be in commercial operation and must meet the locational requirements for HILLGA prior to CHILLS being granted.  

Therefore, the load owner must coordinate all four required processes:  

• The HILL load study 
• The HILLLGA generation study 
• The CHILLS eligibility review 
• Attachment BA supplemental requirements 

The load owner must also coordinate with the retail electric service provider for the area of interconnection. That provider will initiate the AX/HILL/HILLLGA/CHILLS processes with SPP.  

Does CHILLS Change Planning Assumptions?

CHILLS does change planning assumptions, but only selectively.  

It does:  

• Allow load to energize prior to network upgrades being completed and Designated Resources being established 
• Introduces conditional operating constraints 
• Includes specific metering/telemetering and data access requirements
• Require load shedding compliance procedures 

It does not:  

• Grant firm deliverability 
• Trigger Network Upgrades only for CHILLS 
• Change firm planning models 
• Convery supporting generation to firm deliverability  

How EPE Can Support You in This Process

EPE has extensive experience supporting large load developers within SPP. Serving as your on-call partner and advisor, we can help you understand utility-specific needs and requirements and prepare utility intake forms for initial load discussions.  

We can guide you through the full process to help you:

• Understand options and risks
• Satisfy new SPP requirements for detailed load data and modeling
• Evaluate system impacts, potential for Network Upgrades, and curtailment risks

To discuss potential HILL/HILLGA or CHILLS projects in SPP, contact our team using the form below.