Interconnection Standards

October 27, 2014


In July 2006 the District of Columbia Public Service Commission (PSC) initiated a formal inquiry into the development of uniform interconnection procedures for on-site distributed generation systems. The PSC subsequently concluded that an interconnection standard was feasible and continued with the rule making process, culminating with the adoption of final interconnection regulations in February 2009 (DC PSC Order No. 15182). The rules apply to all distributed generation systems of 10 megawatts (MW) or smaller that are operated in parallel with the electric distribution system and are not subject to the interconnection requirements of the PJM Interconnection.

The interconnection rules set four levels of review for interconnection requests. A project must meet all of the requirements of a given classification in order to be eligible for that level of expedited review. The level of review required is generally based on system capacity, whether system components are certified, and the type of distribution circuit to which a facility will be connected. The basic definitions* for each level are as follows:

  • Level 1: Certified, inverter-based systems with a capacity rating of 10 kilowatts (kW) or less.
  • Level 2: Certified systems with a capacity of 2 MW or less, connected to a radial distribution network or a spot network serving one customer. Area network connections are not permitted under Level 2.
  • Level 3: Only applies to systems that will not export power to the grid. For area networks (3A), systems must be certified and have a capacity of 50 kW or less; or for radial distribution networks (3B), systems must have a capacity rating of 10 MW or less.
  • Level 4: Systems with a capacity of 10 MW or less that do not meet the criteria for inclusion in a lower tier, generally including all systems that require additional construction by the utility in order accommodate the facility.

The interconnection regulations generally use IEEE 1547 as a technical standard for evaluation of all levels of interconnection. Systems are considered to be lab-certified if the components have been evaluated by a nationally recognized testing laboratory as compliant with UL 1741 (inverters) and IEEE 1547.1. The rules specify the technical screens which may be applied to applications at each level of review and time limits for different stages of the evaluation process. Generally speaking, higher level applications are subject to more intensive screening and longer time limits.

A lockable external disconnect switch is not required for Level 1 interconnections, but is required for Levels 2 – 4. Facilities larger than 1 MW must carry general liability insurance with coverage of at least $2 million per occurrence and $4 million in aggregate, and the policy must also name the utility as an additional insured party. Standardized interconnection agreements are available for all four levels of review and are available in the February 2009 PSC Notice of Final Rulemaking. The interconnection agreements for all four levels are attached to the final rules. The rules and accompanying standard forms also contain details regarding application fees and avenues for dispute resolution.

The PSC adopted net-metering rules in February 2005 for residential and commercial electric customers with renewable-energy systems, fuel cells, cogeneration and microturbines up to 100 kilowatts (kW) in capacity. In January 2007 the PSC approved a net-metering tariff filed by Pepco -- the only electric distribution company that serves the District -- which also contained certain technical standards for net metered facilities. Prior to this, in 2003, Pepco had filed an interconnection tariff to address larger qualifying facilities (QFs) under PURPA.

*The definitions here cover several important classification criteria; however, interested parties should consult the actual rule for more precise definitions and additional restrictions.

Program Overview

Implementing Sector: State
Category: Regulatory Policy
State: District of Columbia
Incentive Type: Interconnection
Web Site:
Start Date:
Eligible Renewable/Other Technologies:
  • Geothermal Electric
  • Solar Thermal Electric
  • Solar Photovoltaics
  • Wind (All)
  • Biomass
  • Hydroelectric
  • Municipal Solid Waste
  • Combined Heat & Power
  • Fuel Cells using Non-Renewable Fuels
  • Landfill Gas
  • Tidal
  • Wave
  • Ocean Thermal
  • Wind (Small)
  • Hydroelectric (Small)
  • Anaerobic Digestion
  • Fuel Cells using Renewable Fuels
  • Other Distributed Generation Technologies
  • Microturbines
Applicable Utilities: Investor-owned utilities
System Capacity Limit: 10 MW
Standard Agreement: Yes
Insurance Requirements: Vary by system size and/or type; levels established by PSC
External Disconnect Switch: Not required for inverter-based systems up to 10 kW; required for all other systems
Net Metering Required: No


Name: DCMR 15-4000 et seq.
Date Enacted: 02/06/2009
Effective Date: 02/13/2009


Name: Emil King
Organization: District Department of the Environment
Address: 1200 1st Street, NE
Washington DC 20002
Phone: (202) 673-6700

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.