Rural electric co-ops form engineering group to evaluate smart inverter standards

Smart inverters enable more distributed solar to be added to the grid, and some rural co-ops are evaluating smart inverter standards as more co-op members become prosumers.

December 19, 2025 William Driscoll

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More than 100 rural co-ops have joined an engineering standards interest group formed by the National Rural Electric Cooperative Association, focused on the IEEE 1547 series of standards that specify requirements for smart inverters for distributed solar and battery storage.

When distributed solar installations use smart inverters meeting the IEEE 1547-2018 standard, those inverters can regulate voltage on a distribution circuit, allowing more solar to be installed on each circuit without utility-supplied voltage regulation hardware.

That’s of interest to some rural co-ops, with Jennah Denney, a senior program manager at NRECA, noting that more co-op members “are becoming prosumers.” She spoke on a webinar hosted by Berkeley Lab as part of the U.S. Department of Energy’s Interconnection Innovation e-Xchange.

NRECA formed the Cooperative Engineering Standards Interest Group in recognition that many electricity distribution co-ops “have very limited engineering staff,” while some may not have even one engineer on staff, said David Farmer, a senior principal at NRECA speaking on the webinar. “If there’s anything going on” with the standards-making process “that might be a problem for a small utility, we want to push back on it if we need to, and we’re educating our members as well.”

Denney said that “co-ops need solutions to work within real operational constraints,” noting that rural co-ops typically have long radial feeders, lower load diversity and density, smaller engineering and general staff teams, and fewer parallel paths for redundancy. “This context does matter” for interconnection standards, she said.

There has been a “patchwork of adoption” of the IEEE 1547-2018 standard across the U.S., Farmer said, pointing to a map prepared by the Interstate Renewable Energy Council, “mainly because of technical operational challenges, interoperability challenges, and cybersecurity risk.”

Smaller utilities, he said, “generally lack” the needed expertise and infrastructure. Speaking to a technical audience, he said “A lot of the co-ops say ‘We don’t want to get into this. We’re just going to have them set the power factor at unity. We’re not going to actively regulate the voltage. We’ll adjust to ride-through settings; that’s not too complicated.’”

“On the other hand, some of our co-ops are really out in front of all this,” Farmer said. “La Plata Electric Association in southwest Colorado, where rooftop solar is very popular amongst their membership, realized they were having some high-voltage problems on their system during light load periods.”

“So by applying smart inverters with a simple volt-watt setting, they’re able to restrict the output of the rooftop solar, and bring the voltage back down into compliance. It’s not a complicated thing to implement, because it’s all responded locally. Probably the more complicated part was getting their members to buy into that, because that is going to limit their expected solar output, and they may not get the savings that they expect to see when they’re curtailing the output of the solar.”

Farmer said he expects a revised version of the IEEE 1547-2018 standard that’s “ready for public ballot” to be released soon.

Denney observed that as distributed energy resource penetration grows, “reliability increasingly depends on how well these interconnection standards are implemented, not just written.”

NRECA’s members include 830 electricity distribution cooperatives and 64 generation and transmission cooperatives.

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