Three utilities have received approval from Wisconsin utility regulators to buy the state’s largest renewable energy plant.
On Thursday, the Public Service Commission approved the $649 million purchase of the Koshkonong Solar Energy Center by We Energies, Wisconsin Public Service and Madison Gas and Electric.
The utilities are buying the solar plant from Chicago-based developer Invenergy. The commission approved its construction last year in the towns of Christiana and Deerfield in Dane County, the solar panels covering roughly half of the 4,600 acre site.
The project would host 300 megawatts of solar — enough to power 90,000 homes — and 165 megawatts of battery storage, according to Milwaukee-based WEC Energy Group.
"We are doing this while working to ensure all our customers experience the economic and environmental benefits of our ongoing clean energy transition," Jeff Keebler, president and CEO of MGE, said in a statement.
We Energies and WPS will own 90 percent of the plant while Madison Gas and Electric will own 10 percent.
The project has received the support of renewable energy and environmental groups. RENEW Wisconsin said the plant is the largest addition of zero-emission generation and storage capacity in state history.
"This is going to be one of the anchor renewable energy generating facilities to serve basically the entire state," Michael Vickerman, clean energy deployment manager for RENEW Wisconsin, told Wisconsin Public Radio.
Construction of the plant is set to start later this year and go online by the end of 2025. Vickerman said the addition of Koshkonong would replace the shuttering of coal-fired units at a roughly 1,100-megawatt power plant in Columbia County owned by Alliant Energy, Wisconsin Public Service and Madison Gas and Electric. The plant is set to be shutdown by mid-2026 after supply chain constraints and fears of an energy shortage postponed its retirement.
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Vickerman said the completion of the Koshkonong, Darien, Badger Hollow and Paris renewable energy projects will reduce the state’s output of carbon emissions from electric power sources by roughly 10 percent.
The commission rejected a request from utilities to buy the project at up to 110 percent of its cost, or up to $752.6 million. Utility regulators instead approved the purchase with conditions from commission staff, which noted they denied a similar request on the Paris solar-battery project in Kenosha County.
Wisconsin’s Citizens Utility Board, said in a filing to the commission that the request "erodes cost protections for customers."
"We're really banking on this being cost-effective based on the construction cost," Tom Content, the board's executive director, told WPR. "We have seen other cases where the construction costs for solar projects have gone up."
The second phase of the Badger Hollow solar farm increased at least $32 million last year due to supply chain constraints and higher labor costs, according to the Wisconsin State Journal.
Utilities must notify the commission within 30 days if the project is expected to exceed $649 million. Regulators would then review their potential for recovering any costs in a future rate case.
While regulators have approved the purchase, the plant has been met with local opposition. Nearby residents had expressed concerns about the project’s effects on property values, loss of farmland, safety concerns with battery storage and its proximity to homes and a nearby school.
The town of Christiana filed a lawsuit in Dane County Circuit Court against the Public Service Commission last year after regulators approved its construction. The town had urged regulators to deny the purchase.
In a commission filing, an attorney for the town argued "the utilities would be left with worthless ownership interests" if a judge reverses the commission’s decision that granted approval for construction. A judge has yet to rule in the case.
Editor's note: RENEW Wisconsin and the Citizens Utility Board are underwriters of Wisconsin Public Radio.