Interconnection Standards

July 28, 2020


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.


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.

Program Overview

Implementing Sector: State
Category: Regulatory Policy
State: Montana
Incentive Type: Interconnection
Web Site:
Start Date:
Eligible Renewable/Other Technologies:
  • Solar Photovoltaics
  • Wind (All)
  • Hydroelectric
  • Wind (Small)
Applicable Utilities: Investor-owned utilities and cooperatives
System Capacity Limit: 10 MW
Standard Agreement: No
Insurance Requirements: Not addressed
External Disconnect Switch: Required
Net Metering Required: No


Name: Mont. Code § 69-8-601 et seq.
Date Enacted: 1999
Name: Administrative Rules of Montana 38.5.84
Effective Date: 8/13/2010


Name: Will Rosquist
Organization: Montana Public Service Commission
Address: 1701 Prospect Avenue
Helena MT 59620-2601
Phone: (406) 444-6359

This information is sourced from DSIRE; the most comprehensive source of information on incentives and policies that support renewables and energy efficiency in the United States. Established in 1995, DSIRE is operated by the N.C. Clean Energy Technology Center at N.C. State University.