Distribution Interconnection Today

See the full video of Lydic’s presentation and below the video, a summary including:

• Common interconnection pitfalls
• Resolving interconnection challenges
• Export limiting and power control systems (PCS)
• UL 3141
• Evolution of state interconnection rules
• Opportunities to improve process

Interconnection process

The interconnection process generally begins with an application that the utility reviews for completeness. Once complete, the project enters technical evaluation, usually through a fast-track or simplified process for smaller systems. The utility applies technical screens covering issues such as DER penetration, minimum load, voltage, fault current, grounding, and shared transformers. Successful projects pass to approval, construction, any required witness testing, and permission to operate. Projects that fail may enter supplemental review or a more detailed study, potentially leading to system upgrades, additional costs, and longer timelines.

Common interconnection pitfalls

Projects may fail because of incomplete applications, or they may get trapped in technical screens because of high DER penetration or limited hosting capacity, shared-secondary or transformer constraints, grounding and voltage concerns, poorly defined queues, missed utility timelines, inadequate treatment of energy-storage load, and upgrade costs that can be much higher than expected. Utilities sometimes tell applicants only that a project failed a screen without providing the calculations or thresholds behind the decision, making it difficult to understand or address the problem.

Resolving interconnection challenges

First, understand the applicable interconnection rules. Identify exactly where a problem occurs, and determining whether it reflects a legitimate technical issue, utility noncompliance, or a weakness in the rules. The quickest resolution is usually through the utility. Document the facts. Propose a solution that addresses safety and reliability concerns. Identify an effective contact such as an interconnection ombudsperson. If all else fails, applicants can use informal dispute resolution through the regulator, raise recurring problems with the regulator, or ultimately pursue formal action. Broad, systemic problems may require participation in working groups or rulemakings.

Export limiting and power control systems

Export limiting allows the interconnection evaluation to consider how much power can be exported to the distribution system—the project’s “export capacity”—rather than automatically treating the full nameplate rating as the grid impact. Power control systems can monitor export and control inverters to maintain the specified limit, and interconnection screens and power-flow studies can account for that limitation. This can reduce evaluated grid impacts and allow more DER to connect with fewer or lower-cost upgrades.

UL 3141 certification

Power control systems are being certified to UL 3141, which at the time of the presentation was an Outline of Investigation moving through the process of becoming an American National Standard. Standardization provides increasing clarity about how these systems should function and adds safety through certification testing. UL 3141 also addresses power export and import limiting and energy-storage operating modes, including safeguards such as fail-safe evaluation and restricted access to settings.

Evolution of state interconnection rules

States are gradually updating interconnection rules to recognize smart inverters, storage, and power control systems. Hawaii and California set early examples for export-control provisions. Illinois, Massachusetts, Maine, Maryland, Michigan, Minnesota, and New Jersey are moving toward rules that accept power control systems. States are also beginning to use smart-inverter functions to address voltage constraints and avoid some upgrades.

Helping the process move smoothly

Applicants can reduce delays by understanding the applicable rules and questions before submitting, making sure applications are complete and accurate and taking advantage of available hosting-capacity information and pre-application reports to identify viable locations before filing. It also helps to know timelines for each step and document interactions with the utility. These measures can help prevent an application from being returned for incompleteness and identify potential capacity or technical problems before they become costly surprises.

Potential areas for improvement

There are many ways to make interconnection more transparent, predictable, and automated, including better-defined queues and timelines, more useful hosting-capacity maps and pre-application reports, clearer explanations of why projects fail technical screens, better processes for storage, and more consistent recognition of export limiting and smart-inverter capabilities. There is also potential for greater automation and even pre-completed analyses, although utility digital models and data are not yet sufficient everywhere. Longer-term improvements could come through state working groups, regulatory proceedings, and updated interconnection rules.

Question-and-answer session

During a question-and-answer session focused Lydic’s presentation, SEAC members discussed how DERs fit into utility interconnection rules, and how those rules could become faster and more accessible for small systems. One key theme in the Q&A was that interconnection rules are designed to protect the grid, but their complexity and lack of modern digital utility data can make small DER projects unnecessarily difficult or expensive. Lydic generally favored moving toward more automated, pre-cleared, data-driven interconnection while maintaining appropriate grid protections. He also said terminology and regulatory treatment have to catch up with newer technologies such as power-control systems, batteries, vehicle-to-grid (V2G) technology, and small plug-in DERs. A second major theme was the risk of overly restrictive “non-export” configurations: today’s interconnection or NEM requirements should not unnecessarily prevent batteries and other DER from providing valuable grid services in the future.  

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