Joint Plant (Tables)

3 Months Ended

Mar. 31, 2026

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 March 31, 2026(a)

         Estimated Date of Commercial Operation

         Darien(b)(c)

         10%

         Battery

         7.5 MW

         $18 million(j)

         $7.4 million

         2027

         Koshkonong(b)(d)

         10%

         Solar/Battery

         30 MW/16.5 MW

         $93 million(j)

         $65.9 million

         2026 Solar
2027 Battery

         High Noon(b)(e)

         10%

         Solar/Battery

         30 MW/16.5 MW

         $99 million

         $60.1 million

         2027

         Columbia Energy Dome(b)(e)

         19%

         Storage

         3 MW

         $22 million(j)

         $2.0 million

         2027

         Badger Hollow(b)(f)

         10%

         Wind

         11.2 MW

         $36 million

         $5.6 million

         2027

         Whitetail(g)

         10%

         Wind

         6.7 MW

         $23 million

         $1.2 million

         2027

         Dawn Harvest(b)(h)

         10%

         Solar

         15 MW

         $34 million

         $1.4 million

         2027

         Ursa(b)(e)

         10%

         Solar

         20 MW

         $46 million

         $6.5 million

         2028

         Saratoga(b)(i)

         10%

         Solar/Battery

         15 MW/5 MW

         $46 million

         $11.9 million

         2028

         Good Oak(b)(e)

         10%

         Solar

         9.8 MW

         $22 million

         $1.7 million

         2028

         Gristmill(b)(e)

         10%

         Solar

         6.7 MW

         $15 million

         $1.6 million

         2028

(a)

Excluding AFUDC.

(b)

MGE received specific approval to recover 100% AFUDC. During the three months ended March 31, 2026, MGE recognized $3.1 million, after tax, in AFUDC for these projects compared to $1.6 million for the comparable period in 2025.

(c)

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

(d)

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

(e)

Located in Columbia County, Wisconsin.

(f)

Badger Hollow Wind is located in Iowa and Grant Counties, Wisconsin.

(g)

Whitetail Wind is located in Grant County, Wisconsin.

(h)

Dawn Harvest Solar Energy Center is located in Rock County, Wisconsin.

(i)

Saratoga Solar Energy Center is located in Wood County, Wisconsin.

(j)

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.