SunZia Transmission Requests Cancellation of Amended Generator Interconnection Agreement

Strategic Insights -

SunZia Transmission, LLC has filed a notice with the Federal Energy Regulatory Commission (FERC) to cancel its Amended and Restated Generator Interconnection Agreement dated June 17, 2025, with SunZia Wind PowerCo LLC. The agreement, which was filed as Docket No. ER25-2541-000, provided for the interconnection of wind-powered electric generating facilities to the Switching Station and the delivery of up to 3,201 MW of electric energy from the facilities to the SunZia Transmission System. The cancellation is effective as of October 28, 2025, the date of the filing and the effective date of the Amended SunZia LGIAs.

The agreement was filed by SunZia Transmission on June 18, 2025, and was accepted for filing by the Commission's Office of Energy Market Regulation, acting on delegated authority, on May 24, 2023. The Amended GIA incorporated certain agreed-upon modifications to Appendices A, B, and C of the Original GIA. However, due to the recent changes in the transmission ownership and the company's status as a Subscriber Participating Transmission Owner (SPTO), the agreement is no longer necessary.

SunZia Transmission has already entered into new jurisdictional agreements and modified certain existing agreements in connection with its transition to a SPTO. The SunZia South and North Large Generator Interconnection Agreements, filed on October 24, 2024, and accepted for filing on February 21, 2025, have been revised to incorporate certain agreed-upon modifications to Appendices A, B, and C of each agreement. The Amended SunZia LGIAs were accepted for filing as of October 28, 2025, the effective date requested by SunZia Transmission.

Key Takeaways:

  • SunZia Transmission has filed a notice with FERC to cancel its Amended and Restated Generator Interconnection Agreement with SunZia Wind PowerCo LLC.
  • The agreement was filed on June 18, 2025, and was accepted for filing by the Commission's Office of Energy Market Regulation on May 24, 2023.
  • The cancellation is effective as of October 28, 2025, the date of the filing and the effective date of the Amended SunZia LGIAs.
  • The original agreement provided for the interconnection of up to 3,201 MW of electric energy from the wind-powered facilities to the SunZia Transmission System.
  • SunZia Transmission has transitioned to a Subscriber Participating Transmission Owner (SPTO) and has entered into new jurisdictional agreements and modified certain existing agreements.
  • The Amended SunZia LGIAs were accepted for filing as of October 28, 2025, and supersede the Amended GIA.

Statistics:

  • 552-mile bi-pole high voltage direct current (HVDC) 500 kV transmission line is being constructed by SunZia Transmission.
  • The transmission line will have a planned transmission capacity of 3,021 MW in New Mexico and Arizona.
  • SunZia Transmission commenced the construction of the transmission line in 2023.
  • Commercial operations are expected to begin in the first half of 2026.
  • The Transmission System has been developed as a merchant transmission project with negotiated rate authority contingent on the allocation of its transmission capacity.

Sources:

  • 18 C.F.R. § 35.15 (2024)
  • SunZia Transmission, LLC, Docket No. ER25-2541-000 (July 31, 2025) (unpublished letter order)
  • SunZia Transmission, LLC, Docket No. ER23-1472-000 (May 24, 2023) (unpublished letter order)
  • SunZia Transmission, LLC, Docket No. ER25-3340-000 (Oct. 23, 2025) (unpublished letter order)
  • SunZia Transmission, LLC, Docket No. ER25-3341-000 (Oct. 24, 2025) (unpublished letter order)