ACQUISITIONS AND DISPOSITIONS (Tables)

12 Months Ended

Dec. 31, 2023

Business Combination and Asset Acquisition [Abstract]

Schedule of asset acquisition

Asset Acquisitions

Project Facility	Resource	Seller	Approximate Nameplate Capacity (MW)	Location	Southern Power Ownership Percentage	Expected/Actual COD	PPA Contract Period
Asset Acquisitions During 2023
Millers Branch(a)	Solar	EDF Renewables Development, Inc.	200	Haskell County, TX	100%	Fourth quarter 2025	20 years
South Cheyenne	Solar	Hanwha Q Cells USA Corp.	150	Laramie County, WY	100%	Second quarter 2024	20 years
Asset Acquisitions During 2021
Deuel Harvest(b)	Wind	Invenergy Renewables LLC	300	Deuel County, SD	100% of Class B	February 2021	25 years and 15 years

(a)The project includes an option to expand capacity up to an additional 300 MWs. Subsequent to December 31, 2023, Southern Power committed to expand the construction of the facility through a second phase adding up to 205 MWs, with commercial operation expected to occur in the second quarter 2026.

(b)In March 2021, Southern Power acquired a controlling interest in the project from Invenergy Renewables LLC and completed a tax equity transaction whereby it sold the Class A membership interests in the project. Southern Power consolidates the project's operating results in its financial statements and the tax equity partner and Invenergy Renewables LLC each own a noncontrolling interest.

Schedule of construction projects

Project Facility	Resource	Approximate Nameplate Capacity (MW)	Location	COD	PPA Contract Period
Projects Completed During 2022
Garland Solar Storage(a)	Battery energy storage	88	Kern County, CA	September 2021 through February 2022(b)	20 years
Tranquillity Solar Storage(a)	Battery energy storage	72	Fresno County, CA	November 2021 through March 2022(c)	20 years
Projects Completed During 2021
Glass Sands(d)	Wind	118	Murray County, OK	November 2021	12 years

(a)In 2020, Southern Power restructured its ownership of the project, while retaining the controlling interests, by contributing the Class A membership interests to an existing partnership and selling 100% of the Class B membership interests. During 2021, Southern Power further restructured its ownership in the battery energy storage projects and completed tax equity transactions whereby it sold the Class A membership interests in the projects. Southern Power consolidates each project's operating results in its financial statements and the tax equity partner and two other partners each own a noncontrolling interest. See Note 9 under "Lessor" for additional information.

(b)The facility has a total capacity of 88 MWs, of which 73 MWs were placed in service in 2021 and 15 MWs were placed in service in 2022.

(c)The facility has a total capacity of 72 MWs, of which 32 MWs were placed in service in 2021 and 40 MWs were placed in service in 2022.

(d)In December 2020, Southern Power purchased 100% of the membership interests of the Glass Sands facility.