Wis. Stat. § 196.71: Municipal public utility contracts.

If a municipality owns a public utility and if there is no other public utility furnishing the same service, the commission, after a public hearing and determination that the municipally owned public utility cannot be operated profitably, may authorize a contract between the municipality and any person not a public utility to furnish light, power or electric current to the municipality upon terms and conditions approved by the commission. The person contracting with the municipality is not a public utility solely due to the contract with the municipality.