UL & cETL Certification for Solar Batteries in the US
If you are selling or installing storage in the United States, "UL listed" stops being a nice-to-have and becomes the gate to permitting. Here is what each mark actually covers, and where buyers get misled.
The three marks that matter
| Standard | Covers | Why it matters |
|---|---|---|
| UL 1973 | Battery cells, modules, packs | The base safety standard for stationary storage. Without it, the battery itself won't pass. |
| UL 9540A | Fire propagation (thermal runaway spread) | Required by most AHJs and the 2021 IFC. Tests whether a failing cell spreads to the rack. |
| UL 1741 | Inverter / power conversion | Grid-interactive inverters must be 1741 SA compliant to interconnect. |
| cETL | Equivalent NRTL listing (Intertek) | Accepted in the US and Canada; functionally equal to the UL mark. |
cETL vs UL — the question every buyer asks
cETL is Intertek's listing mark and is a Nationally Recognized Testing Laboratory (NRTL) listing, just like UL. Both are accepted under the US electrical code and in Canada. Some inspectors still say "UL listed" out of habit, but cETL meets the same requirements. If a supplier tells you cETL is "less than UL," they are either misinformed or steering you to a more expensive option.
The gap buyers miss: component marks ≠ system approval
A UL 1973 battery and a UL 1741 inverter do not automatically make your system "UL 9540 certified." UL 9540 is the system-level standard, and final approval comes from the Authority Having Jurisdiction (AHJ) inspecting the as-built installation — enclosure rating, clearances, ventilation, and signage. Buy the right component marks, then let a licensed installer handle system sign-off.
What we ship for the US market
- Battery packs built to UL 1973 cell-level safety; fire-tested per UL 9540A propagation method
- Inverters with UL 1741 SA grid-interconnect compliance
- cETL marking available on request for US/Canada projects
- Full documentation package (test reports, SDS, wiring diagrams) for the AHJ
Building a US-compliant storage system?
Send your state and AHJ requirements — we'll spec cells, packs, and inverters with the marks your inspector will accept.
Get a US-spec quote →Frequently asked questions
What UL certifications does a US home solar battery need?
Three: UL 1973 (battery), UL 9540A (fire propagation, required by most AHJs and the 2021 IFC), and UL 1741 (inverter). The cETL mark is the Intertek equivalent of UL listing and is accepted across the US and Canada.
Is cETL the same as UL?
cETL is Intertek's NRTL listing and is functionally equivalent to the UL mark. Both satisfy US and Canadian code requirements; some inspectors ask for "UL listed" by habit.
Does a UL mark on the battery mean the whole system is approved?
No. UL 1973 and UL 1741 do not auto-grant UL 9540 system certification. The installer still submits the as-built system for AHJ inspection.