Koshkonong Solar Energy Center

• Koshkonong Solar Energy Center is proposing a 300 megawatt (MW) photovoltaic (PV) solar electric generation facility and 165 MW Battery Energy Storage System (BESS) in the Towns of Christiana and Deerfield, Dane County, Wisconsin. The proposed project study area covers approximately 6,384 acres (9.98 square miles) of primarily agricultural land and some grasslands and upland forest, of which approximately 2,400 acres (3.75 square miles) would be disturbed to host the proposed solar facilities. The major components of the project would include PV panels, power conversion units (which include an inverter and transformer), approximately 75 miles of 34.5 kilovolt (kV) underground collector circuits, a collector substation, a new approximately 0.84-mile 345 kV generator tie line, and a 165 MW BESS that would potentially sit on 15 acres of land. The solar arrays, substation, and BESS would be fenced, and the applicant has provided 2,200 acres (3.45 square miles) of alternative solar array sites for evaluation and use if needed.


• Applicant stated need: This project is proposed by an independent power producer, Koshkonong Solar Energy Center, a wholly-owned subsidiary of Invenergy. As such, the need for the project is not reviewed by the Commission. Koshkonong Solar Energy Center has stated that they intend to either; own and operate the project or develop and sell the project to a utility or independent power producer. Subsequently, an application was jointly filed by Wisconsin Electric Power Company (WEPCO), Wisconsin Public Service Corporation (WPSC), and Madison Gas and Electric Company (MGE) to acquire the Koshkonong Solar Energy Center under docket 5-BS-258.


• Estimated cost: This project is proposed by an independent power producer, and the Commission does not review the project cost or need. The cost to Wisconsin Utilities, and ratepayers, would be reviewed when the proposed facility is proposed to be purchased by a Wisconsin Utility, or Utilities. This information will be reviewed in Docket 5-BS-258, as mentioned above.


• Project Location: The project would be located immediately west of the Village of Cambridge, approximately 6 miles northeast of the City of Stoughton, 2 miles south of the Village of Deerfield, 7 miles north of the City of Edgerton, and 10 miles west of the Cities of Jefferson and Fort Atkinson.


• Proposed schedule:
  • ​The application was submitted to the Commission on April 15, 2021.
  • ​If approved, the proposed construction schedule for this project is to begin in Spring of 2022. The project is proposed to be completed and in service by December of 2024.

Documents

• Application for ​Certificate of Public Convenience and Necessity (April 2021)
• Environmental Assessment (October 2021)

Case Contacts and Additional Information

• Staff Involved: this tab contains contact details for PSC staff assigned to the docket, including the case coordinator and the environmental review coordinator
• Documents: this tab contains a complete list of docket documents categorized by document type

• Interactive Web Map of Project (external link)
• Project overview map (.pdf)

The solar electric generation facility is a Type III action under Wis. Admin. Code § PSC 4.10(3).Type III actions normally do not require preparation of an Environmental Assessment (EA) or an Environmental Impact Statement (EIS) under Wis. Admin. Code § PSC 4.10(3). However, an evaluation of a specific Type III proposal may indicate that the preparation of an EA is warranted for that proposal. In addition, Koshkonong is seeking approval to construct a battery energy storage system (BESS) which is a Type II​ action under Wis. Admin. Code § PSC 4.10(2). The Commission will prepare an EA for this project that will evaluate the location of the project and its potential environmental, community, and private property impacts. There will be a preliminary determination when the EA is complete that will determine whether the preparation of an EIS is necessary.