Joint Plant (Tables)

9 Months Ended

Sep. 30, 2024

Public Utilities, Property, Plant and Equipment [Abstract]

Schedule of Jointly Owned Utility Plants

MGE has ownership interests in generation projects with other co-owners, some of which are under construction, as shown in the following table. Incurred costs are reflected in "Property, plant, and equipment, net" or "Construction work in progress" on the consolidated balance sheets.

Project	Ownership Interest	Source	Share of Generation	Share of Estimated Costs(a)	Costs incurred as of September 30, 2024(a)	Estimated Date of Commercial Operation
Paris(b)	10%	Solar/Battery	20 MW/11 MW	$61 million(d)	$48.6 million	2024 Solar 2025 Battery
Darien(c)	10%	Solar/Battery	25 MW/7.5 MW	$63 million(d)	$41.9 million	2025 Solar 2026 Battery
Koshkonong(e)	10%	Solar/Battery	30 MW/16.5 MW	$104 million(d)	$6.6 million	2026 Solar 2027 Battery
West Riverside	3.5%	Natural Gas	25 MW	$25 million	$25.2 million	(f)

(a)Excluding AFUDC.

(b)Paris Solar-Battery Park is located in the Town of Paris in Kenosha County, Wisconsin.

(c)Darien Solar Energy Center is located in Walworth and Rock Counties in southern Wisconsin.

(d)Estimated costs are expected to exceed PSCW previously approved Certificate of Authority (CA) levels. Notifications are provided to the PSCW when costs increase above CA levels. MGE has and will continue to request recovery of the updates in its rate case proceedings.

(e)Koshkonong Solar Energy Center is located in the Towns of Christiana and Deerfield in Dane County, Wisconsin.

(f)In June 2024, MGE purchased an additional ownership interest in West Riverside, a natural gas-fired facility located in Beloit, WI, from WPL, operator and co-owner of the plant. West Riverside was placed in-service in 2020. MGE's interest in West Riverside increased to 6.9%.