Largest solar project in Wisconsin gets regulatory approval


State regulators have given the go ahead to Invenergy to construct the largest solar project, or at least tied for the largest project, in the state’s history, a 300MW solar and 165MW battery energy storage installation on around 4,600 acres in the towns of Christiana and Deerfield.

The battery’s duration has not yet been made available, however project of this caliber tend to utilize 4-hour duration battery systems, which would equate to 660MWh. The project, which has been dubbed the Koshkonong Solar Energy Center is expected to inject $140 million into the local economy over the life of the plant and create 600 jobs during peak construction, according to Invenergy. Once complete, a number of utilities owned by WEC Energy Group and Madison Gas and Electric plan to spend $649 million to buy the plant from Invenergy.

We Energies and Wisconsin Public Service will 90% of the solar and battery storage project, assuming the deal goes through, while Madison Gas and Electric will own the remaining 10 percent. Construction is to start later this year with a target date of December 2024 for completion.

The Koshkonong Solar Energy Center is ties for largest project with Wisconsin is Madison Gas and Electric Badger Hollow Solar Farm, another 300MW installation that had its first phase completed in 2021. Located near Montfort and Cobb in Iowa County in Wisconsin, west of Madison, Madison Gas and Electric owns 50MW of the 150MW Phase I, while Wisconsin Public Service owns the remaining 100MW. Construction is underway on the 150MW second phase of the project, of which Madison Gas and Electric will own 50MW and Wisconsin Public Service will own 100MW.

While Wisconsin has historically been middle of the pack in terms of installed solar nationally and slightly ahead of the pack for the Midwest, with roughly 840MW installed to date, according to the Solar Energy Industries Association, the state has recently seen an uptick in large-scale development activity.

In March, WE Energies, Wisconsin Public Service, and Madison Gas and Electric signed on to purchase stake in the Paris Solar project, an Invenergy-developed solar PV and battery energy storage facility. Sized at 200MW of PV and 110MW of lithium-ion battery energy storage, which won regulatory approval in 2020.

In 2021, Wisconsin regulators voted to allow Alliant Energy’s subsidiary, Wisconsin Power and Light, to buy or build, own, and operate six solar electric facilities with a combined capacity of 675 MW. Prior to this decision, regulators also approved 1,078 MW of utility-scale solar generation in Wisconsin..

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