The opening of the CAISO Cluster 16 (QC16) Interconnection Request Window is rapidly approaching, and developers are actively preparing projects for submission. Cluster 16 will be the first major interconnection cycle following CAISO's interconnection process reforms, which CAISO implemented to address the unprecedented queue volumes and processing challenges experienced in previous cluster windows.
CAISO’s Key Queue Cluster 16 Dates
- CAISO Transmission-Level Interconnection Requests: For projects seeking interconnection to transmission facilities under CAISO operational control, the Cluster 16 application window is scheduled to open on October 1, 2026, and close on October 15, 2026.
- WDAT Distribution-Level Interconnection Requests: Projects seeking interconnection through a participating utility's Wholesale Distribution Access Tariff (WDAT) will need to submit during the utility-specific application window, which is expected to close before the CAISO transmission-level window opens.
For SDG&E and PG&E, a timeline has yet to be provided, but WDAT projects in these two utilities will primarily consist of smaller generation and storage resources interconnected at distribution voltages below 50 kV.
Southern California Edison (SCE) has indicated that its WDAT Queue Cluster 16 window is anticipated to run from September 11 through September 25, 2026. SCE presents a unique opportunity for larger projects under WDAT because it maintains significant sub-transmission infrastructure that is not under CAISO operational control. As a result:
- Projects interconnected to 66 kV facilities can be as large as approximately 110 MW.
- Projects interconnected to 115 kV facilities can be as large as approximately 200 MW.
- Projects interconnected to facilities below 50 kV will support smaller-scale projects.
This creates a potentially attractive pathway for utility-scale developers seeking alternatives to CAISO-controlled transmission interconnections in load pockets where Deliverability is readily available.
Why CAISO Queue Cluster 16 is Different
Cluster 16 will be the first major interconnection cycle conducted under CAISO's enhanced queue management framework developed in response to the excessive number of applications submitted during Cluster 15. CAISO's recent interconnection reforms were specifically designed to improve queue quality and prioritize projects that demonstrate a high level of development maturity. As a result, developers should expect:
- More stringent entry requirements.
- Increased scrutiny of project maturity.
- Stronger commercial readiness requirements.
- Greater emphasis on site control and deliverability planning.
- Enhanced screening before project is admitted into cluster studies.
Projects that fail readiness or viability screening will likely be excluded from the study process altogether. Evidence of project maturity, site control, and commercial support will play a critical role in determining whether a project advances.
Projects lacking one or more of these foundational elements should be viewed as high-risk candidates for Cluster 16 participation.
Queue Cluster 16 Readiness Priorities
The table below summarizes the factors most likely to influence project admission and competitiveness.
The Bottom Line
Developers targeting CAISO’s Cluster 16 should assume that only the most mature and well-prepared projects will be competitive.
Successful projects will likely demonstrate:
- Strong site control
- A clearly defined interconnection strategy
- Meaningful commercial support and LSE engagement
- A well-developed deliverability strategy
- Sufficient financial resources to advance through the study process
- A realistic permitting and development plan
In CAISO’s Cluster 16, success will come down to demonstrable readiness to move forward into development and construction of the project. As the application window approaches, now is the time to complete project readiness assessments, finalize development packages, and close any remaining gaps in commercial, technical, and financial preparedness.
Offering end-to-end solutions every step of the way from project onset, EPE is ready to be your partner. To get started, reach out to our experts using the form below.
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