When Will UL 1741 SB Certification Be Required In CA Rule 21?

If you have been participating in the SIWG, FIGII, or UL 1741 SB meetings, you know the challenges of getting the industry certified to UL 1741 SB are receiving more focus. On April 1, 2021, the California IOUs presented what they believe to be a reasonable timeline for transitioning the Rule 21 inverter requirements to UL 1741 SB. They shared a proposed schedule with a March 2022 requirement date and a 6-month window, during which they would accept both “Existing Rule 21” inverters (UL 1741 SA plus) and “Future Rule 21” certified inverters (UL 1741 SB).

One issue not included in the timeline was the upcoming revision to UL 1741 SB, which is becoming the critical path to certification. Tim Zgonena of UL reviewed with the group the status and process of the revision as well as its significance. For example, there are 75-80 “clarifications” to IEEE 1547.1 that vendors and NRTLs are waiting on before completing testing and certification of inverters. Tim was hopeful the final revision would be ready for a 45-day ballot by early May. If everything goes smoothly, a final 1741 SB update could be published in June, though it seems more realistic there may be further issues and delays and a July or August publication date is more probable. At the subsequent SIWG meeting April 15, Tim revised the timeline to early September at the earliest.

Tim further discussed the complexity of 1547.1-2020 versus the prior version. For instance, IEEE 1547.1-2020 is 263 pages versus 54 pages for the first edition. The implication is that certification could take as long as three months with traditional methods of certification testing.

When you factor in the delay in UL 1741 SB and the increased timeline for actual certification testing, if the NRTLs can’t start actual testing until at least June, getting inverters through the process and being listed for California Interconnection by the CEC (California Energy Commission actually verifies certification and maintains the list of approved inverters) by March 2022 seems very challenging. The SIWG will be digesting this new information and reconsidering the schedule again in the coming weeks. At the April 15 SIWG meeting there was discussion about making the required by date 9 or 12 months after the publication of the UL 1741 SB revision. That would put the date in June or September of 2022. But no decision has been made.

Accelerating UL 1741 SB Certifications: QualityLogic’s New IEEE 1547.1 Test Tools

Regardless of the CA Rule 21 schedule, automating UL 1741 SB testing will be critical to accelerating the certification process. That’s why UL, Intertek, TUV, and CSA are all early customers for QualityLogic’s new IEEE 1547.1 test automation tools. We’ve been making great progress on the test tools, and I wanted to give you an update.

Adding SunSpec Modbus Support

Because so many vendors already support SunSpec Modbus we are adding support for it in our 1547.1 Interop testing tools. We already support IEEE 2030.5 in a 1547.1 FTS designed for both Interop and Type testing, and adding SunSpec Modbus means:

  • Vendors using SunSpec Modbus for their local Interop interface can use the same tools used for IEEE 2030.5 Interop testing to 1547.1 requirements;
  • It becomes very easy to support both IEEE 2030.5 and SunSpec Modbus in the same certification process (or add it on later), and;
  • With either protocol, the actual lab systems (inverter, simulators, data collection) are integrated into one test system that automates the full testing process.

We are currently shipping the IEEE 1547.1FTS and Equipment Management beta versions to our customers and plan to ship the SunSpec Modbus beta by the end of May 2021.

Supporting Type Testing

In 2020, we set out to build a test tool to support IEEE 2030.5 Interop testing (Section 6 in IEEE 1547.1). During the process, we put in place the software architecture to support Section 5 Type testing – e.g., any 1547.1 function that requires communications and must be automated. Instead of setting a couple of curves or settings for functions like Volt-VAR, Freq-Watt, etc., we set all the required curves and settings—which could be in the dozens—for each function. This automates all the Type tests from end to end, greatly speeding up the testing (and re-testing) process.

Controlling the Test Equipment

From the start of our development, we wanted to build a system that actually controlled the complete IEEE 1547.1 Test setup consisting of the inverter, grid and DC simulators, and data collection systems. As of April 2021, we’ve implemented an automation engine to remotely control and manage these systems in our NRTL partner labs and at the Portland State University Inverter Lab.

To date, we’ve integrated with Ametek (California Instruments) MX30/MX45, NH Research Grid Simulator NHR9410, Magna Power SL, Yokogawa WT5000 Power Analyzer, Chromas 6200H DC Power Supply.

Vendor Accelerator Program

We are looking for a limited number of vendors that are interested in our test tools to be part of our IEEE 1547.1 Vendor Accelerator Program. This is an opportunity to receive early access to the QualityLogic 1547.1 tools and take advantage of significant discounts and extraordinary support and interaction on the tools. We will integrate the tools into your processes and equipment, including the use of our planned API to interface with your existing 1547.1 test systems.

Be one of the first vendors to use the same tools as the labs, and get through the certification process ahead of the pack!