Interconnection Standards
To remain economically viable, combined heat and power (CHP) systems and other distributed generation (DG) technologies rely on the ability to purchase backup power from the electric grid, and to sell excess electricity they generate back to it. The lack of a consistent standard that explicitly establishes parameters and procedures for connecting to the grid drives up both monetary and transaction costs for technology manufacturers and owners, discouraging CHP deployment.
States need not start from scratch when adopting interconnection standards; there are both technical and institutional models at the national, regional and state levels that have been successfully implemented by California, Ohio, Oregon, and other states. See the resources below for interconnection standard model language.
Emerging interconnection best practices include:
- Coverage of all distributed generation technologies (including CHP)
- Use of existing technical standards: IEEE 1547 and UL 1741
- System capacity limits for small systems up to at least 10 MW
- Screens for complexity and size, allowing fast-track processing for smaller, less expensive, less complex systems
- Standardized interconnection agreement forms
- Transparent, uniform and accessible application information and procedures
- Prohibition of unnecessary external disconnect switches
- Prohibition of requirements for additional insurance
The Interstate Renewable Energy Council has produced a list of each state's interconnection standards. Also see the Network for New Energy Choice's 2009 version of "Freeing the Grid" for a state-by-state scorecard on interconnection and net metering standards.
Other Resources
- [DSIRE] Database of State Incentives for Renewables and Efficiency. 2010. Rules, Regulations & Policies for Renewable Energy website. This online database provides information on current state policies related to net metering and interconnection, as well as links to applicable legislation.
- [FERC] Federal Energy Regulatory Commission. 2005. Standardization of Small Generator Interconnection Agreements and Procedures. Order No. 2006. Washington, D.C.: Federal Energy Regulatory Commission. This order provided the first national standard for institutional interconnection procedures and agreements related to small generators up to 20 MW in size (larger systems are covered in FERC Order No. 2003). While the rule is an important model for state and local decision makers, it is limited to systems that fall under FERC's jurisdiction, i.e. those involved in interstate transmission of power or wholesale power transactions. Most small CHP systems have capacities smaller than 20 MW, and therefore fall under state or local jurisdiction.
- [IEEE]. 2003. 1547-2003 Standard for Interconnecting Distributed Resources with Electric Power Systems. This standard establishes criteria and requirements for interconnection of distributed resources with electric power systems. It provides requirements relevant to the performance, operation, testing, safety considerations, and maintenance of the interconnection.
- [IREC] Interstate Renewable Energy Council. 2009. Connecting to the Grid, 6th Edition. Latham, NY: Interstate Renewable Energy Council. This report provides a comprehensive discussion of the institutional and technical issues surrounding grid interconnection and net metering. It provides particularly thorough coverage of interconnection and net metering standards and current best practices, and addresses continuing barriers to the expansion of CHP and other distributed generation systems.
- ____. 2010a. Model Interconnection Procedures, 2009 Edition. Latham, NY: Interstate Renewable Energy Council. This document provides model legislation for state interconnection policies, with associated explanation of key issues, including program capacity caps and treatment of net excess generation.
- ____. 2010b. State Interconnection Standards for Distributed Generation. Fact sheet produced by IREC's "Connecting to the Grid" Project. Latham, NY: Interstate Renewable Energy Council. This document details state interconnection policies, including eligible technologies, applicable sectors and utilities, limits on system capacity, and requirements for net metering and external disconnection switches.
- [MADRI] Mid-Atlantic Distributed Resources Initiative. 2005. Mid-Atlantic Distributed Resources Initiative Procedures. These procedures for grid interconnection were developed by MADRI, a group formed in 2004 by public utility commissions from mid-Atlantic states to provide regional best practices for interconnection of distributed resources. The procedures have been used as the foundation for Pennsylvania's 2005 Notice of Proposed Rulemaking for new interconnection procedures.
- [NNEC] Network for New Energy Choices. 2009. Freeing the Grid: Best and Worst Practices in State Net Metering Policies and Interconnection Procedures. New York, NY: Network for New Energy Choices. This report provides a scorecard of state progress on net metering and interconnection policies. Both the scoring methodology and recommendations for individual state improvement are provided. It concludes with a discussion of worst and best state practices.
- State of California. 2000. Rule 21. Rule 21 was updated in 2000 by the California Public Utilities Commission to specify interconnection, metering and operating requirements for distributed generators in the state. It has served as a model for other state policies.
- [UL] Underwriter's Laboratory. 2001. Standard 1741. This technical standard deals specifically with safety-related aspects of interconnection.