Projects that are not eligible for Fast Track evaluation or the Independent Study Process, or that failed the Fast Track Process, can apply for the Cluster Study Process. The Cluster Study Process is described thoroughly in Section 4 of the GIP. In the Cluster Study Process, projects are grouped by geographical and system areas to be studied together (as a cluster): upgrades are identified for the clustered group and the cost of the upgrades are then allocated to projects in that clustered group (in accordance with the guidelines of the GIP). The Cluster Study Process consists of a Phase I Interconnection Study and a Phase II Interconnection Study.
A request for interconnection under the Cluster Study Process can only be submitted during a Cluster Application Window. For each calendar year, a Cluster Application Window typically opens (first business day of the month) and closes (last business day of the month) during the month of April of a given year.
Cluster Application Window Schedule* |
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2025 | Queue Cluster 16 | Tuesday, April 1, 2025 | Wednesday, April 30, 2025 |
2024 | Deferred to 2025 | | |
For more information, view SCE’s Rule 21 page.
*Dates are anticipated based on previous Cluster Application Window events. SCE may modify the dates based on ISO’s lead
Cluster Study Process Eligibility. Any project (any location, any size) can request interconnection under the Cluster Study Process.
Interconnection Study Deposit. Interconnection of a generating facility under the Cluster Study Process requires an Interconnection Study Deposit equal to $50,000 plus $1,000 per MW of electrical output (rounded up to the nearest whole MW) of the generating facility, up to a maximum of $250,000. If the request is for an increase of capacity of an existing unit, the deposit is calculated based on the MWs of the proposed increased capacity.
Site Exclusivity Deposit. For projects requesting interconnection under the Cluster Study Process, in lieu of the demonstration of Site Exclusivity, the customer may elect to provide a Site Exclusivity Deposit of $100,000 (if the generating facility is no greater than 20MW) or $250,000 (if the generating facility is greater than 20MW).
Firm Charging Distribution Service. For projects requesting Firm Charging Distribution Service, an additional deposit of $20,000 is required.
Scoping Meeting. Following the notification that the application has been reviewed and is deemed valid and complete, SCE will hold a Scoping Meeting with the customer to review the details of the proposed project and to discuss any potential issues with the proposed Point of Interconnection or the timelines to achieve commercial operations. After the Scoping Meeting, SCE will present to the customer the Generator Interconnection Study Process Agreement (see link for Appendix 3 of GIP above) for execution. The study agreement should be signed and returned to SCE within thirty (30) calendar days from the Scoping Meeting.
Phase I Interconnection Study. The Phase I Interconnection Study will consist of short circuit analysis, a stability analysis to the extent SCE and the CAISO reasonably expect transient or voltage stability concerns, and any other studies that are deemed necessary. Section 4.5.3 of the GIP contains a complete description of the scope and purpose of the Phase I Interconnection Study. Normally, SCE will commence the Phase I Interconnection Study around July 1st following the closing of the Cluster Application Window and will complete the Phase I Interconnection Study within one hundred and seventy (170) calendar days.
Within thirty (30) calendar days following the Phase I Interconnection Study report, SCE, the CAISO (if needed), and the customer will have a Results Meeting to discuss the contents of the report. More details about the scope and timelines of the Phase I Results Meeting can be found in Section 4.5.7 of the GIP.
Initial Posting of Interconnection Financial Security. The customer will make its initial posting of Interconnection Financial Security (as required in Section 4.8.2 of the GIP), within ninety (90) calendar days of the final Phase I Interconnection Study report.
Phase II Interconnection Study. SCE, in coordination with the CAISO, will conduct a Phase II Interconnection Study for the remaining eligible projects from the Phase I Interconnection Study. Section 4.6.3 of the GIP contains a complete description of the scope and purpose of the Phase II Interconnection Study. Normally, SCE will commence the Phase II Interconnection Study around May 1st of the calendar year following the closing of the Cluster Application Window and will complete the Phase I Interconnection Study within two hundred and five (205) calendar days.
Within thirty (30) calendar days following the Phase II Interconnection Study report, SCE, the CAISO (if needed), and the customer will have a Results Meeting to discuss the contents of the report. More details about the scope and timelines of the Phase II Results Meeting can be found in Section 4.6.10 of the GIP.
Second and Third Postings of Interconnection Financial Security. The customer will make its second and third postings of Interconnection Financial Security as required in Sections 4.8.3 and 4.8.4 of the GIP, respectively.
Interconnection Agreement. Normally, SCE will provide the customer a draft GIA, together with draft appendices as follows:
For customers requesting Energy-Only Deliverability Status, within thirty (30) calendar days following the Results Meeting for the final Phase II Interconnection Study report
For customers requesting Full Capacity Deliverability Status or Partial Capacity Deliverability Status, within thirty (30) calendar days following the results of CAISO’s TP Deliverability allocation process
The draft GIA will be in the form of the FERC-approved from GIA, which is in Appendix 5.2 to the GIP - Generator Interconnection Agreement for a Generating Facility Interconnecting Under The Cluster Study Process. The customer must provide written comments, or notification of no comments, to the draft appendices within thirty (30) calendar days. At that point, SCE and the customer will begin negotiations to complete the GIA under the timelines provided in Section 4.9.2 of the GIP.
Notes About Deliverability for Cluster Study Process. Unless specified otherwise in the application for interconnection, generating facilities studied under the Cluster Study Process will be considered Energy-Only (also referred to as Energy Only Deliverability Status, EODS, or EO). Energy-Only projects do not qualify to provide Resource Adequacy benefits to Load Serving Entities (“Resource Adequacy” and “Load Serving Entities” are terms defined by the California Public Utilities Commission).
If in the application the customer requests Full Capacity Deliverability Status (FCDS) or Partial Capacity Deliverability Status (PCDS), a Deliverability Assessment will be performed during the Phase I Interconnection Study. The Deliverability Assessment will identify the Delivery Network Upgrades required to provide the customer with the deliverability status requested (FCDS or PCDS).
Following the Phase I Results Meeting, and based on the findings provided in the Phase I Interconnection Study report, the customer is required to confirm the requested deliverability status, or modify it (as allowed in Section 4.6.1 of the GIP). The GIP also provides options to the customers regarding their deliverability status that may affect their obligation to pay or finance Delivery Network Upgrades. Please refer to Section 4.6.2 of the GIP for additional information on the options available to the customer.
An updated Deliverability Assessment will be performed during the Phase II Interconnection Study. However, the final determination of the deliverability status of the project is done through the CAISO’s TP Deliverability process. Please refer to Section 4.6.13 of the GIP for the timelines related to the CAISO’s TP Deliverability process. Also, please consult the CAISO website and Appendix DD of the CAISO Tariff for the full description of the TP Deliverability process.
Reference Materials from Queue Cluster Window
For Reference, you may review SCE’s WDAT Queue Cluster 14 presentation. This presentation covers the Interconnection Request application form, sample Single-Line Diagrams, site/plot plans, tips on demonstrating Site Exclusivity, required deposits, study, and other timelines, as well as updates to the WDAT applicable to energy storage projects.