Three Sisters Solar Project

Please note that this website has been updated to reflect a change in the footprint of the proposed transmission corridor. See the “Recent Changes” section below.

Delivering valuable capacity to fast-growing Cochise County, Arizona

The BrightNight Three Sisters project will feature 300-megawatts (MW) of solar and 300MW / 1200MWh of battery storage. Located on 2,300-acres in Cochise County, Arizona, this dispatchable power project will provide valuable capacity and economic investment to the region and its energy users. Also, it’s infrastructure will operate without added burden to public systems such water and roads.

  • 300 MW

    Of clean, renewable energy

  • $259M

    Total economic investment over the life of the project

  • $34.1M

    In tax revenue over the life of the project

  • $48.7M

    In direct economic output during construction

  • 250

    Construction jobs and 3-5 permanent O&M careers

  • $15.9M

    In local labor income during construction

There has been a change in the footprint  of the proposed transmission corridor.

This change is due to interest BrightNight has received from manufacturers in potentially co-locating a green hydrogen manufacturing facility with the solar project. In order to serve this potential opportunity, additional transmission infrastructure is necessary beyond what has been communicated to date. The additional 230-kV infrastructure and substation equipment would be required to service the manufacturer’s load. This equipment would be located in the Facility Siting Area, as shown in the two maps below. Additional information about the equipment located in the Facility Siting Area is provided below the maps.

Project Location


Within the Project Substation and Facility Siting Area, the following equipment and features may be included:

  • Project Substation: A new Project Substation located within the dashed line, which will serve to step up power from the Three Sisters Solar Facility to 230 kV transmission voltage for delivery to the grid and/or the local hydrogen manufacturing facility.
  • Behind the Meter (BTM) Service Line:  A 230 kV transmission line from the new Project Substation to a new hydrogen production and liquefaction facility also located within the Facility Siting Area, and
  • BTM Electrolyzer Substations (BTM Substations):  The hydrogen production and liquefaction facility will include up to eight electrolyzers, each of which includes a 230 kV to 34.5 kV transformer (located downstream from the Project Substation) to step down power from transmission voltage to serve the green hydrogen facility.  These BTM Electrolyzer Substations would also be located within the Project Substation and Facility Siting Area.

Project Events & Documents

Three Sisters Community Notice

Project FAQs

Thanks to exciting renewable energy adoption across the United States, most people are familiar with the benefits of solar power. But how it’s developed, constructed, and maintained is complex. We’ve compiled a few FAQs to help address your questions.