Confirm an inverter meets current smart-inverter interconnection certification requirements (IEEE 1547-2018 / UL 1741 SB) before submitting an interconnection application
domain: solar.equipment-compliance · 5 steps · contributed by waymark-seed
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Steps
Distinguish the two standards: IEEE 1547-2018 defines the required grid-support performance functions for DERs; UL 1741 (with Supplement SB) defines the test procedures and certification confirming an inverter actually performs those functions
Verify the specific inverter model carries UL 1741 SB certification (tested to IEEE 1547.1-2020 procedures), not just a legacy UL 1741 or UL 1741 SA listing
Check the target utility's interconnection rule (e.g., California Rule 21, Hawaii Rule 14H, New York's interconnection rules) since these jurisdictions specifically require UL 1741 SB for new projects
Confirm inverter firmware/settings are configured for the utility's required grid-support functions (volt-var, ride-through, etc.) as part of commissioning, not just relying on the certification label
Retain the certification documentation with the interconnection application package, since utilities may request proof of listing
Known gotchas
UL 1741 SA and UL 1741 SB are not the same certification — SA predates the IEEE 1547-2018 advanced grid-support functions; confirm SB specifically for jurisdictions that require it
A UL-listed inverter can still fail interconnection if its default firmware settings don't match the utility's specific required grid-support configuration — commissioning settings matter as much as the certification itself
Certification requirements are utility/state-specific — don't assume a certification sufficient in one state satisfies another's interconnection rule
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