Trend Watch: Grid-Forming Inverters and IEEE 1547 Updates

The grid is shifting to inverter-based resources. From field reviews and standards work I track, the biggest unlock is the move toward grid-forming (GFM) controls, supported by modern interconnection rules. This page explains what GFM inverters do, how IEEE 1547-2018 and IEEE 1547.1-2020 shape requirements and tests, and where UL 1741 SB certification fits so your design decisions are verifiable—not just aspirational.

The Rise of Grid-Forming Inverters

For years, grid-following (GFL) inverters synchronized to an existing waveform and injected current. GFM inverters, by contrast, regulate voltage and can establish a stable reference—making them suitable leaders in microgrids and supportive actors on weak grids. Research summarizes the distinction and cautions that some capabilities (e.g., black-start) may require system-level validation or specific hardware paths. See NREL introduction to GFM controls and NREL black-start notes.

Why GFM Capability Matters Now

As synchronous inertia declines, GFM controls offer fast frequency and voltage support, “virtual inertia” behaviors, and better disturbance response. A coordinated approach—controls, protection, storage sizing, and communications—determines what you actually achieve on site. For an overview of GFM expectations and operating envelopes, see DOE specifications for GFM IBRs.

Decoding IEEE 1547 Updates

IEEE 1547-2018 sets functional requirements for distributed energy resources (DERs) interconnecting with the grid (e.g., ride-through, voltage/frequency support, categories). See NREL highlights of IEEE 1547-2018 and NREL explainer.

From Requirements to Tests

IEEE 1547.1-2020 provides the conformance test procedures to verify that DER equipment meets 1547-2018. Public summaries are available here: IEEE 1547.1 overview and industry advisory.

Certification: Where UL 1741 SB Fits

UL 1741 is the safety/certification standard for inverters and related DER equipment. Supplement SB incorporates test procedures aligned with IEEE 1547.1-2020 so products can be listed as meeting advanced grid-support functions. See UL 1741 SB technical summary and IEEE SCC21 page.

Adoption and Profiles

Whether a jurisdiction requires “IEEE 1547-2018 + UL 1741 SB” depends on local adoption. Many entities are transitioning; always verify utility-required settings (profiles) early in design. A public tracker is maintained here: IEEE 1547-2018 adoption tracker. NREL also publishes adoption primers: adoption primer.

Grid-Following vs. Grid-Forming: The Practical Shift

GFL inverters “follow the beat.” GFM inverters can “set the beat” and coordinate mixed resources. In my projects, the most reliable path is: pick equipment listed to applicable profiles, test ride-through and support in the lab (per 1547.1 methods), then confirm field settings with the utility before commissioning.

Design Notes for Solar+Storage Teams

• System objectives first: If you need islanding or black-start, validate that capability as a system (inverter + controls + energy storage + protection). Some GFM behaviors are software-led, but others may require hardware and procedural steps. See GFM intro, black-start study.
• Standards alignment: Use IEEE 1547-2018 functions (e.g., ride-through, droop/volt-var) as the design baseline. Validate by referencing IEEE 1547.1-2020 tests and obtaining a UL 1741 SB listing for the specific product/version.
• Utility profiles: Lock settings with the AHJ/utility (volt/freq bands, trip logic, ramp rates). Requirements can vary by service territory.
• Documentation: Keep a versioned set of test reports, listings, and commissioning settings for review.

Why This Matters Now

GFM controls and modern interconnection rules turn DERs into active grid supporters. Public resources summarize the performance categories and bulk-power considerations, helping designers make defensible choices. See NREL highlights and NREL GFM research hub.

FAQ

Does IEEE 1547-2018 require grid-forming?

No. The standard requires DER support functions (e.g., ride-through, voltage/frequency response). GFM is a control capability that can help meet system-level reliability goals; it is not universally mandated. See NREL 1547-2018 highlights.

How does UL 1741 SB relate to IEEE 1547.1?

IEEE 1547.1-2020 defines the test procedures; UL 1741 SB incorporates those procedures into certification so products can be listed as compliant with the required grid-support functions. See IEEE overview and UL 1741 SB summary.

Is IEEE 1547-2018 mandatory in my area?

It depends on local adoption by commissions and utilities. Check current status and any utility-required profiles. See adoption tracker and adoption primer.

Compliance note: This content is for general information only and not legal advice. Always verify applicable standards, listings, and utility profiles with your AHJ and interconnecting utility.