Renewable Energy System Interconnection Standards

NREL provides information and resources to U.S. states and communities on interconnection standards—how renewable energy systems can be legally connected to the electricity grid.

Interconnection standards are a set of requirements and procedures for both utilities and customers. Typically, they outline a multistep process. In some jurisdictions, simple systems (e.g., smaller and inverter-based) can be eligible for simplified, or fast-tracked, interconnection approval processes. For more complex systems, or in jurisdictions where simplified interconnection is not available, interconnection is generally a multistage process.

While interconnection standards are usually implemented at the state regulatory level and mandate how utilities must connect renewable energy systems to the electric grid, there is often a parallel permitting process required by a local jurisdiction (e.g., municipal building permit department) to ensure that residents' systems are installed safely by installers, contractors, or the residents themselves.

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Regulatory Background

In the United States, state-level public utility commissions (PUCs) establish interconnection standards that customers and utilities must follow. Standards vary by state. Additionally, in May 2005, the Federal Energy Regulatory Commission (FERC) enacted interconnection standards for projects up to 20 MW for projects subject to FERC's jurisdiction. These are called the Small Generator Interconnection Procedures.

Most states do not regulate cooperatives and municipal electric companies.

Benefits

Interconnection standards establish transparent processes for multiple stakeholders to follow ensuring safe deployment of renewable energy systems. Transparency also provides more certainty and less risk for renewable energy system investors and developers.

Implementation Issues

Unclear, lengthy, and complicated interconnection standards may increase distributed generation “soft costs” (i.e., nonhardware costs), thereby delaying the deployment of renewable energy systems. Although most states have net energy metering policies, some have not followed through with interconnection policy or rulemaking and have deferred responsibility to utilities.

Design Best Practices To Support Distributed Generation

Although interconnection standards are not consistent across states and utilities, many states adopt engineering and safety requirements based on IEEE 1547 and UL 1741 standards. Additionally, state interconnection standards are increasingly modeled after FERC's Small Generator Interconnection Procedures. Interconnection standards can also vary by: