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Raising standards for interconnecting renewables across the US: Utility Commissions Q&A with IEEE

By Ravi Subramaniam

Ravi Subramaniam currently serves as the Director of the Conformity Assessment Program (ICAP) at the US-based Institute of Electrical and Electronics Engineers (IEEE).

Renewables such as solar, energy storage and other distributed energy resources (DERs) are playing a growing role in the world’s energy landscape. Innovation of standards around DERs are helping policymakers around the world work through their stakeholder processes for updating rules and requirements to manage the trends.

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Since its initial publication in 2003, IEEE 1547™, IEEE Standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems Interfaces, has informed legislation, regulatory deliberations and engineering and business practices for utilities in markets worldwide. For example, the U.S. Energy Policy Act of 2005 references IEEE 1547. As DER deployment has increased, new market challenges have emerged, and IEEE 1547 has been refined accordingly. The most recent, 2018 update to the standard addressed numerous changes related to the rising levels of DERs interconnecting to the grid.

Within the U.S., different jurisdictions are at different points of DER adoption and interconnection. In this Q&A, officials with multiple public utility commissions (PUCs) discuss the uniquely different drivers and dynamics in their jurisdictions.

Ravi Subramaniam: Is your jurisdiction looking at updating its DER interconnection requirements/rules? 

Wally Nixon, legal advisor, Arkansas Public Service Commission: We have an investigatory docket on DER, No. 16-028-U, which has been underway for a couple of years. An Interconnection Working Group has just begun to meet, and I anticipate that it will make recommendations to the commission. The net-metering rules, including provisions governing interconnection, are addressed in Docket No. 16-027-R, where a major order (Order No. 28) was issued June 1, making significant changes to the net-metering rate structure and a few changes to the interconnection standards. The net-metering rules will not be finalised for several months, following possible rehearing and then legislative review and approval. 

Michelle Rosier, distributed energy resources specialist, Minnesota Public Utilities Commission: We began updating our statewide interconnection standards in 2017 in two phases: first, the interconnection process and agreement, and, second, the technical interconnection and interoperability requirements. The statewide standards had not been updated since initial adoption in 2004. The commission intends to maintain an ongoing Distributed Generation Workgroup to meet annually, or more frequently as needed, to review issues that arise with implementation of statewide interconnection standards or emerging DER technology.

Edward Yim, energy policy advisor, District of Columbia Department of Energy and Environment: The work is ongoing to examine various issues such as adopting IEEE 1574, streamlining net energy metering (NEM) interconnections, allocating distribution system upgrade costs for community renewable energy facilities (CREFs) and expanding hosting capacity. The last major updates were made in October 2016 under Order 18575 in Formal Case 1050. Subsequently, Public Service Commission (PSC) of the District of Columbia (DC) initiated a rulemaking proceeding in 2017 for additional updates to small generator interconnection rules, including consideration of IEEE 1547 standard. The work remains in progress.

RS: What are some of your local drivers of DER penetration?

Wally Nixon, Arkansas: We have very low DER penetration (~0.5%), but significant growth in distributed solar is now occurring under a new 2019 law (Act 464, Ark. Code Ann. Sec. 23-18-601 et seq.) that authorized leasing and made other significant changes to net-metering. The threshold for net-metering facilities was raised from 300 kW to 1 MW (below which customers are not required to come to the commission), and there are different provisions for projects between 1 MW and 20 MW.

Michelle Rosier, Minnesota: Minnesota statute gives the maximum possible encouragement to cogeneration and small power production consistent with protection of the ratepayers and the public. As of 2019, Minnesota had 9,168 DERs interconnected at the distribution level totaling over 1 GW of installed capacity. In Minnesota, DER installed capacity has increased 500 percent since 2016. Minnesota’s largest utility, Xcel Energy, has over 680 MW of community solar gardens (typically 1 MW systems), which have been installed since 2016. State statute outlines net-metering options for up to 40 kW for cooperative and municipal utilities and 1 MW for investor-owned utilities. Several utilities offer incentives for residential and small, commercial-size systems in part to meet the state energy policy goals. Minnesota’s statewide interconnection standards apply to DER up to 10 MW operated in parallel with a utility’s distribution grid.

Edward Yim, DC: The main driver is the Renewable Portfolio Standard (RPS) Expansion Amendment Act, which increased the requirement to buy electricity from locally generated solar systems, incrementally increasing to 5 percent of total electricity sales in DC by 2032, and to 10 percent by 2040. The requirement comes with a significant non-compliance or alternative-compliance fee that drives the adoption of solar systems. In a city that is short on open space, this mandate effectively requires most available roof space to host solar systems. For DC to achieve this legislative target, PSC must develop and enforce rules that remove barriers to interconnection and examine ways to expand hosting capacity, using both traditional and non-wires solutions. Another driver is the anticipated net-zero building code, which would require the use of onsite renewable energy.

RS: What unique dynamics of DER integration must your commission account for?

Wally Nixon, Arkansas: The need for hosting capacity analysis, data access, customer protection, interoperability and cybersecurity—the whole litany of issues.

Michelle Rosier, Minnesota: Minnesota utilities are in the process of investing in tools and infrastructure to more actively manage the distribution grid, including better understanding of more localised and time-varying load shapes. While DER penetration statewide is still relatively nascent, some pockets of distribution grids are seeing high enough penetrations to trigger distribution upgrades or the need for operating agreements and advanced inverter functions. In 2018, the commission began requiring integrated distribution plans from rate-regulated utilities.

Edward Yim, DC: DC’s energy and climate plan, Clean Energy DC, specifically calls for using DER to lower the carbon footprint in its energy sector, to reduce costs associated with peak demand, to provide resilience to critical infrastructure and underserved communities, and to help achieve its vision of net-zero energy buildings. Grid modernization stakeholders have advocated the use of non-wires alternatives (NWAs) to help relieve capacity constraints, and PSC is requiring DC’s electric utility, Pepco, to formally incorporate NWAs in its planning process. 

Battery storage paired with solar and smart inverters will likely be needed in any realistic net zero scenario. Image: LG Chem / SolarEdge.

RS: How is leveraging IEEE 1547-2018 valuable in your stakeholder process for evolving requirements and rules for interconnecting DERs?

Wally Nixon, Arkansas: The commission understands the importance of updating our interconnection standards to enable greater participation by DERs and third-party providers.

Michelle Rosier, Minnesota: The commission and our stakeholders look to incorporate national standards in statewide standards as a best practice to ensure safety, reliability and streamlined interconnection and ongoing operation of DER.

Edward Yim, DC: Our PSC has received extensive input from grid modernisation stakeholders on the value of the IEEE standards for DER interconnection, including use cases such as a building developer seeking to use an onsite solar-plus-battery system to achieve net zero energy and for backup power without onerous interconnection requirements while ensuring safety. The input also included the potential to use the functionalities in advanced inverters to provide more options and flexibility for Pepco to expand hosting capacity of a given circuit.

RS: How would you summarise the outlook for DERs and renewables?

Wally Nixon, Arkansas: The commission has expressed its intent to accommodate greater penetration of DERs and grid modernization in Docket No. 16-028-U. Order No. 10 in 2018 launched multiple workshops to gather stakeholder input, and these continue today, albeit hampered by COVID-19 constraints. Additional virtual workshops and working groups will continue for the next year or more.

Michelle Rosier, Minnesota: As of 2018, utilities had approved plans to procure 45% of generation capacity from renewables by 2030 statewide, and several have announced goals beyond that. The number of DER interconnections has increased each year; however, annual capacity additions have declined from a high in 2017. Minnesota is fortunate to have utilities, DER industry representatives and consumer advocates committed to working together and developing the record for the commission to address DER issues ranging from interconnection and integration to program and compensation design.

Edward Yim, DC: The outlook is very positive for renewable DERs in DC and nationally. DERs have a prominent role in DC’s climate and action plan, Clean Energy DC, and it is even featured in our climate adaptation plan, Climate Ready DC. I see DER referenced increasingly and prominently in state energy plans and cities’ climate plans, and it is referenced strongly in the House Select Committee on the Climate Crisis Climate Action Plan as a solution to decarbonising the building and energy sectors. In DC, we will look to DERs to create neighborhood-based virtual power plants (VPP), reduce our carbon footprint, bring energy resiliency to important community facilities and critical infrastructure and make our buildings net-zero energy and eventually net-zero carbon.


Given the rapid rise of DER deployments around the world, IEEE 1547 is an increasingly important resource to regulators, utilities, DER developers, equipment manufacturers and other stakeholders globally. To learn more about IEEE Standards Association's efforts related to IEEE 1547, please reach out to [email protected].

Cover Image: IEEE. 

Read a related Guest Blog on IEEE 1547.1-2020 and how it will “pave the way for U.S. states to adopt more modern interconnection requirements for DERs on the grid, contributing to the grid modernisation that will be needed to support high levels of renewable energy and energy storage,” from Brian Lydic, chief regulatory engineer at the Interstate Renewable Energy Council (IREC): 'The long-awaited IEEE standard that paves the way for more energy storage on a smarter grid'.

The title of this piece has been amended to reflect the fact that the interviewees are officers at public utility commissions and are not commissioners themselves.  

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