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
alike.

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.

Leading and lagging states alike may recognise that interconnection standards are a linchpin to the advent of a more modern grid, but they need assistance as they work toward the adoption of next generation best practices, especially to address the uniquely flexible and controllable nature of energy storage.

A growing number of states (such as Maryland and Nevada, most recently) are updating their outdated interconnection standards to more proactively address energy storage, which is creating a clearer path for this game-changing resource to play a bigger role going forward. Other states that have never had statewide standards are now beginning to examine and adopt interconnection rules. Arizona is one example of a state that had no statewide standards but in November adopted comprehensive interconnection rules that address energy storage.

Key questions for statewide interconnection procedures to address

Ideally, to clarify the process for all involved stakeholders, the questions below should be clearly addressed in statewide interconnection procedures:

APPLICABILITY & ELIGIBILITY

SYSTEM SIZE & REVIEW PROCESS

TIMELINES

DISPUTE RESOLUTION

INFORMATION SHARING & TRANSPARENCY

Let’s get on the right road!

As if all of these issues aren’t enough to consider, there are a number of interconnection related questions that states and utilities will need to address as a result of the adoption of the IEEE Standard 1547 TM -2018 for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems Interfaces. This voluntary, nationally applicable Standard by the Institute of Electrical and Electronics Engineers (IEEE) will transform how DERs interact with and function on the grid.

More specifically, the Standard requires DERs to be capable of providing specific grid support functionalities relating to voltage, frequency, communications and controls. Once widely utilised, these functionalities will enable higher penetration of DERs on the grid, while maintaining grid safety and reliability and providing new grid and consumer benefits.

Clearly defining DER settings in statewide interconnection rules will help increase efficiency, minimise confusion, and reduce costs.

States or utilities which have not yet adopted interconnection rules could begin the process today with IREC’s Model Interconnection Procedures in hand as a useful starting point that reflects best practices that will help ensure a more efficient and affordable process for all involved stakeholders, including customers adopting clean energy technologies.

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