As US states work to address and enable the swift growth of distributed energy resources (DERs), including solar and energy storage, the issues surrounding their interconnection to the electric grid require close attention.
Not only to maintain safety and reliability as new technologies connect to the grid, but also to provide a clear, transparent and efficient process for customers, developers and utilities
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Interconnection procedures are the rules of the road for the grid. Without common rules and predictable processes, gridlock and costly projects can result. Alternatively, the adoption of statewide interconnection standards (i.e., rules that apply to all regulated utilities) that reflect well-vetted best practices can provide greater consistency across utilities and help streamline the grid connection process for all involved stakeholders. Interconnection rules are designed to handle current and anticipated growth of DERs, while also enabling more cost-effective and efficient clean energy projects.
In particular, interconnection standards can help states address the integration of newer technologies that are transforming the energy system, i.e., energy storage, solar-plus-storage, and smart inverters. Energy storage in particular requires more explicit provisions to address its unique flexibility and ability to operate differently based on different applications.
What’s so special about energy storage?
So, for example, energy storage is controllable in a way not typically seen with distributed generation, such as rooftop solar. Many energy storage systems can be designed with the capability to limit or prevent export onto the grid, which impacts how the system should be studied and interconnected to the grid.
In IREC’s recently released 2019 Model Interconnection Procedures, we take the first steps toward defining a clear interconnection process for energy storage systems to provide a useful starting point for states navigating these issues. By addressing the unique qualities of energy storage, the 2019 procedures create an initial framework for reviewing energy storage and verifying energy storage system capabilities.
IREC’s model procedures have been around since 2005 (with updates made in 2009 and 2013) and have served as a template for nearly all states that have adopted statewide interconnection standards. In addition to addressing energy storage, the 2019 edition provides other needed updates to reflect new best practices for interconnection.
However, the model procedures do not yet resolve every question around energy storage.
For example, they do not address how to screen those energy storage systems that may have some “inadvertent export” for a very short duration in response to sudden customer load fluctuations. But as the interconnection of energy storage evolves in the coming years, best practices for how best to analyse their grid impacts will continue to emerge.
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