Public utilities: electric utilities; establishment of microgrids; provide for. Amends sec. 10a of 1939 PA 3 (MCL 460.10a).

SB 477 sets a 10% annual cap on the portion of an electric utility's weather-adjusted retail sales that can be served by alternative energy suppliers, directly affecting Michigan utilities and their customers seeking to switch providers. The bill includes key exceptions: facilities already using alternative suppliers since 2008 (including expansions), iron ore mines/processing facilities in the Upper Peninsula under specific settlement agreements, and customers on a pre-2016 enrollment queue. It requires utilities to maintain a confidential queue for new customers and adjust the cap downward if usage remains below 10% for five years. The law aims to balance customer choice with grid stability for Michigan's electric utilities.