Interconnecting Generation under SCE’s WDAT

SCE’s Wholesale Distribution Access Tariff (WDAT) describes the terms under which SCE provides open access to its distribution system to wholesale customers seeking to:

  • Interconnect generation facilities to SCE’s distribution system and deliver energy and capacity services to the California Independent System Operator (CAISO) controlled grid (using SCE’s distribution system), or
  • Deliver energy or capacity services from the CAISO controlled grid (using SCE’s distribution system) to their customers.

The WDAT is not applicable for customers seeking service under SCE’s retail rates, or for delivering energy or capacity services that do not originate or terminate at the CAISO controlled grid, or for any other purpose not authorized by the Federal Energy Regulatory Commission (FERC).

Each of California’s large investor owned utilities (IOUs) has its own WDAT. The information on this page serves as a reference for SCE’s WDAT. Specifically, this material is for developers of projects seeking to interconnect their generating facilities to SCE’s distribution system for the purpose of participating in wholesale energy transactions. In case of discrepancies between the content of this page and SCE’s WDAT, the currently approved WDAT will prevail. Note that the WDAT currently posted at may not reflect updates to the tariff that may be pending before the FERC.

Generator Interconnection Procedures. Currently, new requests for interconnection of generating units to SCE’s distribution system from wholesale energy producers are processed under the WDAT’s Attachment I - Generator Interconnection Procedures (known as the “GIP” or “G.I.P.”). Links to the WDAT, the GIP and all appendices are provided below.

     Summary of Changes to the Wholesale Distribution Access Tariff

                                   Tariff changes effective October 30, 20191

  • For energy storage projects, the Interconnection Customer must choose the type 
    of Charging Distribution Service: Firm Charging Distribution Service (FCDS), As Available Charging Distribution Service (ACDS), a combination of As-Available and Firm, or None
  • Attachment K to the WDAT lists the rates, charges, and exemptions for Charging Distribution Service
  • Attachment K also includes Constraint Management System (“CMS”) requirements for energy storage projects
  • The WDAT Fast Track Process is now available to energy storage project requesting ACDS
  • Revised Interconnection Request (“IR”) form (Appendix 1 to GIP)
    • IR form now includes distribution service information (Section 10); thus, neither a separate Distribution Service request nor a deposit is required
    • IR form now includes a new Section 11 in Attachment A “Storage System Information”. Thus, the “additional technical data form,” or BESS Form, is no longer required
    • IR form now includes new/modified boxes in Section 2 regarding increasing or modifying Charging Capacity
  • Additional Study Deposit is required for storage projects requesting FCDS ($20,000)
  • Cluster study timelines will add forty-five (45) calendar days for storage projects requesting FCDS
  • Added and modified definitions
  • SCE recommends visiting the Wholesale Distribution Access Tariff (WDAT) expandable section found on our Regulatory – FERC Open Access Information page for additional changes

1SCE submitted storage-related tariff changes in FERC Docket No. ER19‐2505-000; FERC accepted SCE’s filing subject to refund, effective October 30, 2019, and set the proceeding for settlement. Following the conclusion of settlement procedures and final order from FERC, additional changes to the WDAT may be required, which could impact your proposed project.

DISCLAIMER: The guidelines in this section are provided with the intent to help SCE’s customers understand SCE’s Interconnection Procedures. However, in the case of discrepancies with SCE’s rules, such tariffs and regulations will prevail.