IEEE 1547 Compliance Push Accelerates as 18 States Legislate Grid
- Power Quality Regulatory Standards & Compliance
Marin Holt
- 0
- 4 minutes read
- EPRI published 2025 update confirming IEEE P1547 revision is actively underway for next edition
- 18 states introduced grid-enhancing technology legislation in 2025, with 9 signing bills into law
- IEEE 1547-2018 caps Total Rated Current Distortion at 5%, harmonized with IEEE 519 strictest category
- U.S. DER capacity projected to grow 217 GW by 2028 per Wood Mackenzie
- UL 1741 Supplement B certification verifies advanced grid-support functions for IEEE 1547-2018 compliance
The distributed energy resource (DER) interconnection landscape is undergoing a significant shift. EPRI’s 2025 update on the IEEE P1547 revision signals the ongoing development of the next iteration of this critical standard. Concurrently, 18 states introduced legislation in 2025 concerning grid-enhancing technologies, with nine enacting those bills into law. This dual regulatory focus represents the most substantial period of DER standards enforcement since the publication of IEEE 1547-2018 in April 2018.
What Is Changing
IEEE 1547-2018 mandates that smart inverters maintain operation during minor grid disturbances and actively contribute to voltage and frequency stability. This contrasts with the earlier 2003 standard, which required disconnection during such events. The current standard establishes specific harmonic limits, capping Total Rated Current Distortion at 5%, aligning with the most stringent category of IEEE 519. Compliance is confirmed through UL 1741 Supplement B certification, which assesses advanced grid-support functions like volt-var, frequency-watt, and ride-through capabilities.
Enforcement Reality
While NARUC unanimously recommended state adoption in February 2020, implementation remains uneven. California, Hawaii, and Minnesota were early adopters, but many states continue to apply pre-2018 interconnection requirements. The IEEE SCC21 committee tracks state adoption progress. With U.S. DER capacity projected to increase by 217 GW by 2028, standardized interconnection requirements are essential for grid reliability as DER penetration grows.
State-by-State Status
Information on specific state legislative actions and adoption timelines for IEEE 1547-2018 and related grid-enhancing technologies is tracked by organizations like the IEEE SCC21 committee and IREC. The Bipartisan Policy Center also provides insights into state-level energy policy developments.
Why It Matters
States delaying IEEE 1547-2018 adoption risk power quality degradation as DER penetration increases without modern ride-through and voltage support mandates. The ongoing P1547 revision aims to address remaining gaps, including dynamic voltage support during abnormal conditions. For utilities and DER developers, UL 1741 SB certification ensures equipment meets advanced performance requirements that safeguard both the distribution grid and end-use power quality. This aligns with the broader goals of FERC Order 2222, which promotes DER participation in wholesale markets.
Critical Perspective
The current enforcement reality faces several hurdles. A significant bottleneck exists in testing laboratories for UL 1741 SB certification, slowing down equipment approval. Utility adoption of these new standards also lags, creating uncertainty for developers. Furthermore, the cost of updating DER inverter firmware to meet these requirements presents a financial challenge. Exemptions for rural utilities also present a potential gap in comprehensive grid modernization efforts.
