Interconnection Standards

The Maine Public Utility Commission (PUC) adopted interconnection procedures in January 2010; the rules were last updated in 2020. These rules apply to all transmission and distribution utilities operating in the state and apply to all distribution generation (not just renewables). Maine's interconnection procedures, based in part on the Interstate Renewable Energy Council's. 2006 Model Interconnection Procedures,* identify four different tiers with corresponding technical screens. These are:

• Level 1: Small certified generating, inverter-based facilities 25 kilowatts (kW) or less;
• Level 2: Certified facilities 2 megawatts (MW) or less;
• Level 3: Non-exporting, certified facilities 10 MW or less;
• Level 4: Any generating facility that does not qualify for the aforementioned levels of review, and are not subject to jurisdiction of the Federal Energy Regulatory Commission (FERC).

Fees and Requirements

Fees for interconnection requests increase with each level. A Level 1 request must submit a $100 fee; a Level 2 request must submit a fee of $100 plus $2/kW of generator capacity; a Level 3 request must submit $100 plus $3/kW of generator capacity; and a Level 4 request must submit an application fee of $3,000. In addition, Level 4 applicants are responsible for fees associated with the interconnection study, as well as any utility upgrades required to accommodate the requested interconnection. Project designs require review and approval by a Maine Licensed Professional Engineer for generators greater than 50 kW.

Equipment Standards

The PUC specifies that IEEE Standard 1547 (“Standard for Interconnecting Distributed Resources with Electrical Power Systems”) and UL 1741 ("Inverters, Converters, and Controllers for Use in Independent Power Systems") as the technical standards of evaluation. Systems are considered to be certified for interconnection if the components have been tested and listed by a Nationally Recognized Testing Laboratory (NRTL) and if they meet the definition of certification under FERC Order 2006 for Small Generator Interconnection Procedures, according to these standards. Additional controls (such as external disconnect switches) are not permitted when facilities use certified equipment. 

Insurance Requirements

Depending on the size of the small generator facility, insurance requirements differ. No insurance is required for inverter-based facilities with a rated capacity of 1 MW or less. Inverter-based facilities with a rated capacity exceeding 2 MW but less than or equal to 5 MW must carry liability insurance with coverage of at least $1 million. Facilities with rated capacity greater than 5 MW must carry liability insurance with coverage of at least $2 million. Insurance coverage for non-inverter-based generating facilities ranges from no insurance (50 kW or less) to $3 million (for facilities greater than 5 MW).

Government Standard Form Interconnection Agreement

In May 2014, the PUC adopted a standard form interconnection agreement for use exclusively by federal government entities. The agreement is a modified version of the standard form interconnection agreement, with changes made to comply with the Antideficiency Act, the Federal Tort Claims Act, and the Automatic Payment of Judgments Act. Under this agreement, federal government entities will self-insure and are not required to carry insurance.

* IREC updated its model interconnection procedures in 2013. The 2013 model is available on IREC's website.

The information provided here covers several important classification criteria and provides a brief summary of the procedures. Consult the actual rule for official definitions, additional restrictions, and comprehensive information on the technical screens.