Battery Energy Storage Systems (BESS)

There are a variety of battery types that can be used for BESS projects, however, lithium-ion batteries are the dominant technology because they are the most commercially mature battery storage option available.  As of July 2026 in Wisconsin, the PSC has only reviewed lithium ion based BESS projects and one new CO2-based Energy Dome project from Alliant.

While the risk is low, BESS pose a higher risk than solar panels, which is why they are subject to stricter standards for design and maintenance, including requirements to reduce the risk of thermal runaway, where a battery cell generates uncontrollable heat. Wisconsin currently follows the 2021 International Fire Code (IFC), which includes references to NFPA 855 for the installation and fire suppression of energy storage systems, and developers are responsible for demonstrating compliance with these standards as part of the permitting and approval process. The RESET Wisconsin Report includes more information on the

Code adoption and enforcement typically happens at the state level, meaning many local planners may lack direct enforcement authority. That is why dialogue with developers and joint agreements are useful tools for BESS. For information on this, consult the PNNL Energy Storage in Local Zoning Ordinances.