Skip to main content

Interconnection Standards

Interconnection standards dictate how renewable energy systems can be legally connected to the electricity grid. They are a set of requirements and procedures for both utilities and customers.

Typically, interconnection standards outline a multi-step process. In some jurisdictions, simple systems (typically 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 two-stage 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.

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 megawatts (MW) for projects subject to FERC’s jurisdiction. These are called the Small Generator Interconnection Procedures (SGIP).

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., non-hardware costs), thereby delaying the deployment of renewable energy systems. Agreement on which types of systems can qualify for certain types of screening can also be difficult to reach.

Design Best Practices to Support Solar 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 SGIP (see Background section above). Interconnection standards can also vary by:

  • Net metered vs. non-net metered systems
  • System capacity requirements
  • Eligible technologies
  • Eligible sectors (e.g., commercial, residential)
  • Fees
  • Insurance requirements.

For an example of a utility that has streamlined the interconnection process, see Decreasing Soft Costs for Solar Photovoltaics by Improving the Interconnection Process: A Case Study of Pacific Gas and Electric.

Sources

Ardani, K., Davidson, C., Margolis, R., Nobler, E. 2015. A State-Level Comparison of Processes and Timelines for Distributed Photovoltaic Interconnection in the United States. National Renewable Energy Laboratory. NREL/TP-7A40-63556.

Database of State Incentives for Renewable and Efficiency (DSIRE). 2016. A comprehensive source of information on incentives and policies that support renewables and energy efficiency in the United States.

FERC. 2005–2016. Standard Interconnection Agreements & Procedures for Small Generators.

Freeing the Grid. Interconnection.

IEEE. IEEE 1547 Standard for Interconnecting Distributed Resources with Electric Power Systems

Palmintier, B., Broderick, R., Mather, B., Coddington, M., Baker, K., Ding, F., Reno, M., Lave, M., Bharatkumar, A. 2016. On the Path to SunShot: Emerging Issues and Challenges in Integrating Solar with the Distribution System. National Renewable Energy Laboratory, Sandia National Laboratories, Massachusetts Institute of Technology. NREL/TP-5D00-65331.

UL. UL1741 Standard for Inverters, Converters, Controllers and Interconnection System Equipment for Use With Distributed Energy Resources.