Interconnection Guidelines

May 21, 2024


NOTE: Delaware law (26 Del. C. § 1014) requires the Delaware Public Service Commission (PSC), Delaware Electric Cooperative (DEC), and municipal utilities to develop interconnection rules using as a guide the Interstate Renewable Energy Council's (IREC) model interconnection rules and the U.S. Department of Energy's best practices for interconnection. This entry largely addresses the rules used by Delmarva Power, the state's largest utility.

Delmarva Power, Delaware's only investor-owned electric utility, has four basic levels of interconnection based on system size and system type (inverter-based or non-inverter-based). In June 2011 the PSC issued Order No. 7984 approving final revised rules to implement net energy metering pursuant to the requirements of S.B. 267. Order No. 7984 provides, among other things, that Delmarva would file revised tariffs, applicable Interconnection Standards for Generators, and such other forms as may be necessary to comply with Order No. 7984 within 30 days of the July 10, 2011 publication of these final rules in the Delaware Register of Regulations. 

Effective August 8, 2011, Delmarva's new guidelines apply to interconnections of all types of distributed generation systems of less than 10 MW to the electric distribution system for the utility. Delmarva now utilizes a four-tiered approach to determine the level of review required before a system may be connected to the grid. Different levels of review are subject to specific technical screens, review procedures, and time lines. Generally speaking, the review process becomes more extensive and time consuming with increasing system size. Below are the basic criteria* for determining the level of review required for a prospective project.

  • Level 1: Lab certified, inverter-based systems with a nameplate capacity of 10 kW or less.
  • Level 2: Lab certified or field inverter-based systems with a nameplate capacity of 2 MW or less connected to a radial distribution circuit or to a spot network serving one customer. Alternatively, the system was reviewed and not approved under Level 1.
  • Level 3: Only applies to systems that will not export power to the grid and which do not require new facility construction by the utility. Systems being located on an area network must be inverter-based, use lab certified equipment, and have a nameplate capacity of 50 kW or less. These systems must have an aggregate generation of 5% of an area network's maximum load or 50kW, which ever is less. Systems located on a radial network must have a capacity of 10 MW or less and not be served by a shared transformer. These systems are also subject to additional criteria dealing with the aggregate capacity of interconnected systems on a given network.
  • Level 4: Systems with a nameplate capacity of 10 MW or less that cannot be approved or do not meet the criteria for review under a lower tier.

An interconnection request may be eligible for expedited review if small generator facilities use lab certified equipment or field approved interconnection equipment. Lab certified equipment is defined to mean equipment tested and approved by a nationally recognized testing laboratory (NRTL) as being in accordance with IEEE 1547, UL 1741, and the National Electric Code (NEC). Field approved systems are generally non-certified systems that have been tested and approved under a review by a utility over the last 36 months and are subject to certain other restrictions including utility witness tests. All interconnected systems must be equipped with a utility accessible “lockable, visible-break isolation device” or alternately, a “draw-out type circuit breaker with a provision for padlocking at the draw-out position”. This requirement is equivalent to “lockable external disconnect switch” frequently specified in other jurisdictions.

Utilities may not charge any processing fees to Level 1 applicants and processing fees are limited to $50 plus $1/kilowatt (kW) of capacity for Level 2 requests and $100 plus $2/kW of capacity for Level 3 and 4 requests. The regulations also contain provisions for dispute resolution, record retention and utility reporting requirements.

Additional insurance requirements vary by the Level of interconnection. The Level 1 interconnection agreement specifically states that applicants are not required to obtain general liability insurance as a condition of interconnection approval, however Delmarva does advise its customers to consider obtaining appropriate coverage to cover potential liability. For small generator facilities with a nameplate capacity of 1 MW or above, the customer is required to carry adequate insurance coverage. Section 7 of the interconnection agreement for Levels 2, 3 and 4 requires continuous liability insurance of at least $2 million per occurrence and $4 million in aggregate for systems of 1 MW or larger. Section 7 also specifies that the policy must name the utility as an additional insured party.

Delaware Electric Cooperatives

Delaware Electric Cooperative's (DEC) interconnection rules use a four-tier system similar to Delmarva's. All systems require lockable external disconnect switches. DEC customers with systems greater than 100 kW are required to carry at least $1 million in liability insurance per occurrence and $1 million in property-loss insurance. Higher amounts of coverage may be required at the discretion of DEC.

For more information on the cooperative interconnection rules, see this link.

*The general descriptions here are not a comprehensive listing of all testing and review criteria. Please see the actual rules for more details and additional restrictions that may apply.

Program Overview

Implementing Sector: State
Category: Regulatory Policy
State: Delaware
Incentive Type: Interconnection
Web Site:
Start Date:
Eligible Renewable/Other Technologies:
  • Solar Thermal Electric
  • Solar Photovoltaics
  • Wind (All)
  • Biomass
  • Hydroelectric
  • Fuel Cells using Non-Renewable Fuels
  • Wind (Small)
  • Anaerobic Digestion
  • Other Distributed Generation Technologies
Applicable Utilities: All utilities (only Delmarva is subject to PSC rules)
System Capacity Limit: 10 MW (limit of Delmarva's standard interconnection agreement)
1 MW for non-renewable cogenerators and small power producers
Standard Agreement: Yes
Insurance Requirements: Vary by system size and/or type
External Disconnect Switch: Required
Net Metering Required: No


Name: Delmarva Interconnection Standards
Effective Date: 08/08/2011
Name: PSC Order 7984
Date Enacted: 07/07/2011
Effective Date: 07/10/2011
Name: S.B. 267
Effective Date: 07/28/2010


Name: Green Power Connection Team
Phone: (866) 634-5571

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.