ComEd - Interconnection Guidelines

April 01, 2008


Illinois does not have statewide interconnection standards in place for distributed generation (DG), but the Illinois Commerce Commission (ICC) is now in the process of developing rules. Individual utility rules are in place to address the interconnection of small-scale DG. The state's largest electric utility, ComEd, has interconnection guidelines for net metering and DG. ComEd's DG rules divide systems into three capacity categories: 25 kVA to 2.5 MVA; 2.5 MVA to 10 MVA; and systems larger than 10 MVA. In general, customer-generators are responsible for all interconnection study charges, and systems must be an eligible qualifying facility (QF) under the Public Utility Regulatory Policies Act of 1978 (PURPA) to receive any payment for power sent to utility. Significantly, there is an exception for net-metered photovoltaic (PV) and wind-energy systems with a capacity less than 40 kilowatts (kW); these systems are not required to file to become a QF. All small systems up to 25 kVA (and net-metered PV and wind systems up to 40 kVA) require a manual, lockable disconnect switch accessible to the utility. However, special interconnection relays are not required. The difference in interconnection requirements for systems in the three capacity categories involves specific relay standards. Procedurally, all systems require a series of reviews by ComEd engineering staff. ComEd does not allow interconnection within "The Loop," an area network that serves the heart of downtown Chicago. As a result, DG systems that could be used as back-up generation for downtown high rises are unable to interconnect.

Program Overview

Implementing Sector: Utility
Category: Regulatory Policy
State: Illinois
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
  • Wind (Small)
  • Fuel Cells using Renewable Fuels
  • Other Distributed Generation Technologies
  • Microturbines
Applicable Utilities: Yes
System Capacity Limit: No size limit for DG rules; 25 kW or 40 kW for net-metered systems /
No limit on installed capacity under DG rules
Standard Agreement: Yes
Insurance Requirements: No
External Disconnect Switch: Yes (for systems < 40 kW)
Net Metering Required: Yes


Name: Maryl Freestone
Organization: Exelon Corporation
Address: ESO Tech. Services, 2nd Fl
Oakbrook Terrace IL 60181-4260
Phone: (800) 825-5436

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.