Solar Energy Project in Darien to Include a 75MW Battery Energy Storage System, Wisconsin
A Major Leap in Renewable Energy: The Darien Solar Project
The Darien Solar Project, located in Rock & Walworth Counties, Wisconsin, marks a significant step forward in the state's renewable energy landscape. This 250 MW solar farm, operational since March 2025, is part of WEC Energy Group's $2 billion investment plan in renewable energy and battery storage by 2025.
The project, spanning approximately 2,000 acres, is a collaborative effort between MGE (Madison Gas & Electric) and WEC Energy's subsidiaries, We Energies and Wisconsin Public Service. The solar capacity is split accordingly, with We Energies and Wisconsin Public Service owning 225 MW and MGE owning 25 MW.
The addition of battery energy storage to the Darien Solar Project is expected to enhance grid reliability and allow stored solar power to be dispatched during peak demand periods. MGE will own 7.5 MW of the 75 MW battery energy storage, which is set to be operational in 2026.
The estimated investment for the project was US$446 million. The Darien Solar Project delivers clean energy to multiple Wisconsin utilities and supports WEC Energy Group's goal of retiring 1,800 MW of fossil fuel capacity and cutting carbon dioxide emissions by 70% before 2030.
Invenergy, one of the largest developers of solar energy in the USA, developed the Darien Solar Project. This project is a testament to the growing trend of solar-plus-storage collaborations in the US. Similar projects, such as the Arevon Energy's Eland Solar-plus-Storage Project in California and the Three Rivers Maine Solar Energy Project, are integrating large-scale solar with storage or significant renewable capacity to support grid reliability and clean energy goals.
Solar and storage capacity additions are rapidly growing nationwide, with Texas, California, and Arizona leading in deployments, including utility-scale solar paired with battery storage. These projects reflect many such collaborations emerging across the US in 2025, contributing to the country's clean energy transition.
In alignment with WEC Energy Group's investment plan, the Darien Solar Project, a collaborative effort between MGE and WEC Energy's subsidiaries, involves financing of $446 million for the construction and development of the renewable-energy industry. The project, which integrates solar power with battery energy storage, will widen the industry's scope beyond merely production, contributing to grid reliability and the trend of solar-plus-storage collaborations in the US.
