Proving Ground Solar and Storage 500kV Interconnect

Father holding toddler outside


Voltage: 500kV
Estimated completion date: 1st quarter 2023
Location: North of Dateland, AZ

Project need
A new 500 kilovolt (500kV) transmission line is required to interconnect a portion of the Proving Ground Solar and Storage Project north of Dateland, from a new step-up substation to the Hoodoo Wash Substation.

Project description
We have partnered with Strata Clean Energy, LLC (Strata) in developing a renewable energy facility in Yuma County, Arizona – the Proving Ground Solar and Storage 500kV Interconnect Project. The project involves a 250-megawatt (250MW) solar photovoltaic generating facility with battery storage, an approximately 6-mile-long double circuit 69-kilovolt (69kV) generation intertie transmission line (gen-tie), a step-up substation, and a 500-kilovolt (500kV) interconnection transmission line (interconnection line) from the step-up substation to the Hoodoo Wash Switchyard. The interconnection line will be an approximately 3,000-foot-long, 500kV transmission line. The solar + storage facility will be located on approximately 2,050 acres of privately owned land, the gen-tie will be located on right-of-way (ROW) from the Arizona State Land Department and Bureau of Land Management (BLM), and the step-up substation and interconnection line will be on ROW from the BLM and across privately owned land. The project and interconnection facilities will be located north of Palomas Road, approximately 10 miles north of Dateland, in unincorporated Yuma County.

Project Map 1
Project Map 2

Project Planning
In 2018, the Yuma County Board of Supervisors approved a special use permit to allow construction and operation of the project in conformance with the Yuma County Zoning Ordinance. A portion of the gen-tie, the step-up substation, and a portion of the interconnection line will be located on rights-of-way obtained from the Arizona State Land Department, across Arizona State Trust land, and from the Bureau of Land Management (BLM). We are currently working with the BLM to amend its existing right-of-way grant to match the final design of the 500kV interconnection line, step-up substation, and associated improvements on BLM-managed lands. Updates and new information will be made available on this website.

A Certificate of Environmental Compatibility (CEC) from the Arizona Corporation Commission and Arizona Power Plant and Transmission Line Siting Committee is required to allow for construction and operation of the 500kV interconnection line. We expect that a portion of the new line will be co-located on structures with the existing 500kV Hassayampa-North Gila #2 transmission line (HANG#2). Co-locating the lines would help consolidate energy infrastructure and minimize the overall impact of the project (see Project Map 2). Although we will be the applicant for the CEC, Strata is continuing the permitting of the project on our behalf.

As part of the public outreach process for the project, Strata held an open house meeting at the Dateland Elementary School in December 2021 to present information about the project, answer questions, and receive comments.

Project features
We are coordinating the design of the interconnection line with Strata and have carefully considered the potential visual impacts in siting the proposed step-up substation and interconnection line. The 500kV portion of the new line would be co-located on existing 500kV structures. Co-locating this portion of the interconnection line will help consolidate energy infrastructure and minimize visual impacts overall. The visual simulations showing existing and proposed conditions from two perspectives on Palomas Road are depicted below.

Simulation #1
Simulation #2

We anticipate that the CEC process will be complete in early 2023, subject to the availability of the Arizona Power Plant and Line Siting Committee. Construction for the project is estimated to begin in Spring 2023.

Project updates
Additional information regarding the schedule for CEC hearings will be posted as it is available. Prior to CEC hearings, we will send informational mailers and email notifications to addresses within the project’s study area. The location and time of CEC hearings will be advertised in the Yuma Sun and posted on signs within the CEC area of the project.

Public input
We welcome feedback for this project. Comments or questions can be submitted the following ways:

Related documents
Newsletter #1
Newsletter #2
Project Overview Boards
Copyright © 2022 APS.  All rights reserved.
Current server address is