UL 9540A 6th Edition Technical Information Service (TIS) Report
TIS Report: 80298264 | Date: May 5, 2026 | Issued by: CSA Group
Client: Lunar Energy, Inc., 755 Ravendale Drive, Mountain View, California 94043
Subject
Evaluation of CSA Reports 80257877 & 80257878 for compliance to UL 9540A 6th Edition (ANS/CAN/UL 9540A:2026 — Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems).
Purpose
This TIS determines whether UL 9540A 5th Edition testing performed on Lunar Energy's L2-ESS-20KWH and LE-DC-UNIT (under CSA Reports 80257877 and 80257878) is equivalent to UL 9540A 6th Edition requirements, and evaluates whether installation-level large-scale fire testing per Section 10 of the 6th Edition is applicable.
Note: After those reports were issued, Lunar Energy updated their model nomenclature from L2-ESS-30KWH to L2-ESS-20KWH + (2) LE-DC-UNIT. No constructional changes were involved; this was handled under TIS Report 80285269.
Assessment
Under UL 9540A 6th Ed. clause 9.1.1, unit-level testing is required for the following applicable conditions — all of which were covered by the testing in Reports 80257877 and 80257878:
Residential use BESS greater than 20 kWh (30 kWh system tested)
Residential use BESS with less than 0.9 m (3 ft) separation to windows or doors
Residential use BESS with non-metallic enclosure (tested including non-metallic external enclosures)
Spacing: Fixed by mechanical interface of wall brackets — no additional spacing required between vertically installed DC ESS units; 6-inch minimum horizontal clearance required to adjacent BESS.
Unit-Level Test Equivalence
No changes were made to the unit-level test methodology when moving from 5th to 6th Edition. Testing in accordance with Section 9 of the 6th Edition is identical to Section 9 of the 5th Edition. Therefore, testing in CSA Reports 80257877 and 80257878 is still valid to UL 9540A 6th Edition. No further unit-level testing is required.
Large-Scale Fire Testing
UL 9540A 6th Edition introduced large-scale fire testing (replacing the Section 10 installation-level test from the 5th Edition). Large-scale fire testing is primarily applicable to non-residential installations, or as the final stage if a BESS does not meet unit-level performance requirements.
Lunar Energy's system is intended only for residential applications. Per Section 9.8.1, large-scale fire testing is not required for residential installations that meet all performance criteria of the unit-level test.
Lunar Energy's system met all performance criteria of Table 9.1 per Reports 80257877 and 80257878.
Conclusion
The unit-level test did not change between 5th and 6th Edition of UL 9540A. The testing conducted under CSA Reports 80257877 and 80257878 is still considered valid to UL 9540A 6th Edition. For residential installations meeting unit-level performance criteria, installation-level large-scale fire testing is not necessary. No further testing is required.
Note: If Lunar Energy markets their system for non-residential installations in the future, an AHJ may require large-scale fire testing before installation approval.
Source document: https://documents.lunarenergy.com/ul-9540a-6th-edition-tis-report