The solar + storage industry evolves rapidly as new technologies and capabilities come to market. Meanwhile, the bureaucratic institutions that regulate how these systems interconnect to the grid usually lag far behind. But some standout states are finally making significant progress on catching up.

The Interstate Renewable Energy Council (IREC) has led the charge on modernizing interconnection across the country. Most recently, the group’s work with the New Mexico Public Regulation Commission (NMPRC) has led to one of the most progressive new interconnection rulings nationwide.

One breakthrough of New Mexico’s ruling was establishing special considerations for energy storage interconnection. Prior rules made no mention of energy storage, leading utilities to either deny non-energy-exporting solar + storage projects or study them as if the battery was fully exporting power to the grid, just like the solar array.

“They’re usually designed to charge from the solar and then discharge into the evening hours, but the default for a utility would be to study [batteries] as though they are simultaneously exporting, which would significantly increase the potential grid impacts,” said Sky Stanfield, lawyer for IREC and partner at law firm Shute, Mihaly & Weinberger.

So IREC and its partners set out to give utilities the required information to study energy storage projects differently, considering the battery’s ability to limit energy exports to the grid. Those “limited exports” are made possible by UL-certified power control systems, which can be programmed based on settings established by utilities. IREC brought research from its Dept. of Energy-supported BATRIES (Building a Technically Reliable Interconnection Evolution for Storage) report to New Mexico’s proceedings to develop these new evaluations or “screens” for energy storage interconnection.

“You give the utilities the confidence that these are safe and reliable means and then you make sure that they’re reviewing the projects appropriately in in the screening process,” Stanfield said.

New Mexico’s ruling also includes what’s known as “inadvertent exports” in storage interconnection planning — meant to address the power that is unintentionally exported from a distributed energy resource when the load drops off suddenly, before the power control system can respond to the signal to limit or stop export, according to IREC.

“New Mexico is the first state to adopt that screen. We think that’s a really important step forward and should give utilities the confidence that they aren’t going to see impacts from inadvertent export and clarifies the process from the developer standpoint as well,” Stanfield said.

The state will also require using smart inverters that comply with the IEEE 1547 standard on new projects starting in spring 2023. Smart inverters can make autonomous decisions to keep the grid stable as more distributed resources come online or the grid’s voltage or frequency fluctuates. Each utility will set forth its own smart inverter technical interconnection and interoperability requirements to ensure it’s in sync with the grid’s needs, but it must align with the NMPRC’s ruling.

Along with new considerations for batteries and inverters, New Mexico’s ruling attempts to expedite the interconnection process. Applicants will now be allowed to make limited modifications to an application to fix any issues that arise in the study process, without being sent to the back of the interconnection queue. This should especially help developers working with utilities that don’t provide much upfront information on grid status.

“Where you don’t have a really detailed hosting capacity map, you can’t figure any of this out in advance. So, the screening and study process becomes a little bit more interactive between the customer and the utility,” Stanfield said.

New Mexico isn’t the only state making progress on streamlining and accurately studying interconnection of solar + storage systems. New York, Maryland, Massachusetts and others have either already implemented or started working on energy storage and smart inverter integration. But those states can look to the Southwest for a holistic road map for interconnection overhaul.

“There’s such a diversity on each issue. It’s hard to say one state has it all. And that’s why I think we’re excited about what the New Mexico rule is,” Stanfield said. “They didn’t just do a little bit of good stuff over here and then backtrack over here. They went ahead and tried to do a comprehensive update.”

This story is part of SPW’s 2023 Trends in Solar. Read all of this year’s trends here.