Interconnection Standards

Summary

In July 2010, the Montana Public Service Commission (PSC) adopted interconnection rules, effective August 13, 2010.  These rules apply to all electric utilities under the PSC's jurisdiction, including investor-owned utilities and co-ops.  Small generators, or systems up to 10 megawatts (MW) located on the land of utility customers within good standing are allowed to interconnect.  While there is no statewide standard interconnection agreement, the largest investor-owned utility in Montana, NorthWestern, does have a standard interconnection agreement for net-metered systems.  The use of certain equipment may qualify a facility for an expedited interconnection review.

Background

Until August 2010, Montana had interconnection guidelines dictated by the net metering legislation, enacted in 1999.  These guidelines required interconnected facilities to comply with all national safety, equipment and power-quality standards established by the National Electrical Code (NEC), the Institute of Electrical and Electronic Engineers (IEEE), the National Electrical Safety Code (NESC) and Underwriters Laboratories (UL). Net metering applies to systems up to 50 kilowatts (kW) in capacity that generate electricity using hydropower, wind or solar energy. The law does not set a limit on the aggregate capacity of systems interconnected to each utility's distribution system.