Before the Institute of Electrical and Electronic Engineers (IEEE) released Standard 1547-2018, it had been 15 years since the international standards organization had provided guidance to manufacturers and utilities on connecting distributed energy resources (DERs) to the main grid. The 2018 version provided much needed updates on the technical standards necessary for equipment like generators and smart inverters to support the rapidly increasing number of DER connections.

Three years on, the North Carolina Utilities Commission (NCUC), Duke Energy and other DER stakeholders are still working on implementing IEEE 1547-2018 — but progress has been slow, the commission heard during a recent hearing. A 2020 addendum to the standard provides guidance for how DERs’ grid-support capabilities will be tested.

John Gajda, principal engineer at Strata Clean Energy, a solar developer, said implementing 1547 would reduce “the cost for the whole value chain and all the stakeholders” in the state.

The NCUC first ordered Duke to examine implementing the standard in 2019, and to date, the utility has created guidelines, held quarterly stakeholder meetings, conducted studies and developed testing requirements. But the work is far from complete and does not yet require any action from the commission, said Anthony Williams, a principal engineer at Duke.

“It’s not just about the capacity but also about uniformity across the DER equipment itself,” he said.

Nationwide, implementation of 1547 has focused largely on “smart inverters,” which convert the DC power from solar panels into AC power for the grid. The inverters can be set to provide “ride-through” capabilities to help local power systems manage voltage or other power fluctuations on the grid. An August 2020 report from IEEE noted that inverters fully compliant with the updated standard may not be available until 2022, creating uncertainty for utilities and regulators.

Minnesota was the first state to full integrate the standard into its interconnection requirements, and the Maryland Public Service Commission has adopted regulations that will fully integrate the standard in 2022.

Preparing for full implementation could be increasingly important for North Carolina as the state has emerged as a solar energy leader with 7,000 MW of installed solar capacity, placing it third in the U.S. behind California and Texas, according to figures from the Solar Energy Industries Association. And the state isn’t stopping — SEIA expects North Carolina will install over 3,000 MW of additional capacity over the next five years.

DER Deployment not Uniform

One of the concerns that Commission Chair Charlotte Mitchell raised was whether the standard needed to be applied to inverters currently on the system or if it would only be relevant for inverters installed moving forward.

Williams was hesitant in his reply, commenting that some functions of existing inverters could comply with 1547, but it would require “taking a hard look to really make sure they had that capability. They may or may not. Our focus is more on applying the 2018 version of the standard to inverters that have been certified to that standard.”

This question was also of concern to Tony Eason, vice president of engineering and operations at Pee Dee EMC, an electric cooperative in the south-central part of the state.

“Would I have to go to one of our rural customers and say, ‘Look you either [have] to bump this up to 1547 or get off the system?’” he asked. “I don’t think that’s very attractive for our membership.”

Another challenge facing Duke and its stakeholders is that the complexity of their discussions will only increase as they dive further into the details, Gajda said. At 138 pages, the standard is incredibly detailed, and the extent to which all the aspects are implemented depends on the utility, he said.

Representatives from the state’s electric cooperatives also raised concerns about how IEEE 1547 would be implemented, especially for co-ops in rural areas.

“DER deployment has not and will not be uniform across our membership,” said John Lemire, director of grid management at North Carolina’s Electric Cooperatives. “The adoption of the IEEE standards will also not be uniform for our members, and we expect the adoption to reflect the existence and materiality of DERs on any system.”

Pee Dee EMC has 21,000 meters spread over 3,500 miles of power lines with 32 DER sites, mostly residential rooftop solar. Eason said it’s more accurate to say “miles per customer rather than customers per mile” because of how rural the region is. While he said it would be helpful to have one comprehensive system for the standard across the state, Eason suggested having multiple implementation options instead.

“Not all utilities are the same,” he said, “The density, conductors, layout of the system, none of this is the same.”

Despite such misgivings, Eason still wants Pee Dee EMC to adopt 1547 because it creates uniform conditions and clearly defines DER settings.

“It’s a complex DER equation that we have to find solutions for on the fly,” he said.

No Lit Fire

Moving forward, Duke will continue to meet quarterly with stakeholders, hashing out details, scheduling pilot tests and checking in with the commission about possible changes, Williams said. But with the utility taking the lead, stakeholders like Gajda wonder how far it will actually advance this work.

“If utilities are not incentivized to maximize DER penetration, then there’s not really a lit fire to move ahead with altering the utility side of the planning and operating standards,” said Gajda. “They can go ahead and clarify the existing 1547 and its little detailed pieces, but the utility is clearly not under an obligation to advance the use of those in a broader sense.”

Duke recently gave a presentation to the NCUC on its integrated grid planning work, during which the message was largely that the utility would be working slowly. Mark Oliver, Duke’s managing director of integrated systems planning, argued that a slow pace was necessary to protect grid reliability and affordability, as the utility sees technologies like energy storage as too cost prohibitive.

Oliver also said that the systems planning work wouldn’t be incorporated into the utility’s integrated resource plans (IRPs) until 2022, and even then, Duke’s DER investments weren’t expected to significantly increase. (See NC Looks at Holistic Approach to Planning.)

Duke’s reluctance to commit fully to DERs is evident in its current IRPs, which anticipate primarily a buildout of natural gas to replace coal. The IRPs present battery storage as too expensive and renewable generation as not reliable enough to meet customer needs, despite studies from North Carolina groups that suggest otherwise. The NCUC is currently in the midst of a series of public hearings on the IRPs which will continue into May. (See NC Net-zero Goals Could Hinge on Duke IRPs.)

While Gajda sees the utility heading in the right direction, he said solar and DER providers are relying on Duke “to move ahead with changes to its planning and operating standards to be compatible with 1547.”

“If there are no changes really considered to the planning and operating standards, then we all know we are operating with unchanged distribution system architecture,” he said. “This needs to be a transparent piece of all of this. Without guidance, things like new inverter regulations risk being used in isolated situations only.”