Vietnam Adds UL 1973 Thermal Runaway Test for C&I ESS Imports

Vietnam’s Ministry of Industry and Trade (MOIT) and the General Department of Standards, Metrology and Quality (STAMEQ) jointly issued a notice on May 6, 2026, mandating that all commercial and industrial (C&I) energy storage systems (ESS) imported into Vietnam must pass the UL 1973 standard’s module-to-module thermal runaway propagation test. Effective July 1, 2026, this requirement applies to all containerized and cabinet-type ESS units. Chinese manufacturers must complete testing and submit reports by May 20, 2026—failure to do so will result in denial of Vietnamese import licenses. This development directly affects exporters, system integrators, and supply chain stakeholders serving the Vietnamese C&I ESS market.

Event Overview

On May 6, 2026, MOIT and STAMEQ published an official notice stipulating that, starting July 1, 2026, all C&I-grade ESS imported into Vietnam must comply with the UL 1973 standard’s thermal runaway propagation test (module-to-module configuration). The notice specifies that Chinese manufacturers must complete the test and submit valid reports no later than May 20, 2026. The requirement covers all containerized and cabinet-style ESS products. No exceptions or transitional provisions were announced in the notice.

Industries Affected

Direct Exporters (China-based ESS OEMs and System Integrators)

These entities face immediate compliance deadlines: failure to submit UL 1973 thermal runaway test reports by May 20, 2026, will block issuance of Vietnamese import licenses. Impact manifests as shipment delays, potential contract renegotiation, and loss of market access for Q3 2026 deliveries.

ESS Component Suppliers (Battery Module & BMS Manufacturers)

Suppliers supporting Chinese OEMs may be asked to provide updated safety documentation or revalidate module-level thermal propagation performance under UL 1973 conditions. Their impact is indirect but operationally consequential—especially if existing modules lack pre-certified thermal runaway propagation data aligned with UL 1973’s specific test protocol.

Logistics and Import Compliance Service Providers

Third-party conformity assessment agents, customs brokers, and certification consultants handling Vietnamese market entry must now verify UL 1973 test report validity—including test lab accreditation status, test scope (explicitly stating module-to-module propagation), and report issuance date—prior to customs clearance applications.

Distribution and Channel Partners (Vietnam-based ESS Resellers & EPC Firms)

Local partners risk inventory obsolescence if unsold stock lacks compliant test reports. Procurement cycles for new projects may extend due to verification requirements, affecting tender timelines and project commissioning schedules for C&I solar-plus-storage deployments.

What Stakeholders Should Focus On and How to Respond

Monitor Official Clarifications from MOIT and STAMEQ

Confirm whether test reports must originate exclusively from UL-authorized labs or if other NVLAP-accredited or IEC 17025-certified laboratories are accepted. Also verify whether reports issued before May 6, 2026—but meeting UL 1973—remain valid, or whether retesting under newly specified parameters is required.

Prioritize Testing for High-Volume or Near-Term Shipments

Allocate testing capacity toward SKUs scheduled for shipment between July and December 2026. Given typical UL 1973 thermal propagation test lead times (4–8 weeks depending on lab backlog), initiating testing before mid-April 2026 is advisable for on-time submission by May 20.

Distinguish Between Regulatory Signal and Enforceable Requirement

This notice establishes a hard deadline for documentation submission—not just a procedural suggestion. However, enforcement mechanisms (e.g., document review depth at customs, penalties for incomplete submissions) remain unclarified. Stakeholders should treat the May 20 deadline as binding while preparing contingency plans for possible administrative delays or interpretation variance during license processing.

Update Internal Documentation and Supplier Coordination Protocols

Revise export checklists to include UL 1973 thermal propagation report validation. Engage battery module suppliers early to confirm availability of test-ready units and alignment of their thermal design documentation with UL 1973 Annex D (thermal propagation test methodology). Where internal BMS or enclosure designs influence propagation behavior, engineering sign-off on test configuration is recommended prior to lab submission.

Editorial Perspective / Industry Observation

Observably, this requirement reflects Vietnam’s broader shift toward aligning ESS safety regulation with international best practices—particularly those emphasizing system-level fire safety in dense deployment environments. Analysis shows it functions less as an isolated technical update and more as an early signal of tightening conformity assessment across ASEAN markets, where harmonization efforts around IEC 62619 and UL 1973 are gaining traction. From an industry perspective, it is not yet a de facto market barrier—but rather a threshold condition whose enforcement rigor will determine its real-world impact. Continued monitoring of STAMEQ’s guidance documents and MOIT’s import license issuance patterns over Q3 2026 will clarify whether this becomes a precedent for broader Southeast Asian regulatory convergence.

This notice marks a concrete step in Vietnam’s formalization of ESS safety governance for the C&I segment. It does not introduce new technology mandates, but rather enforces verifiable, standardized safety validation—making compliance traceable and auditable. For stakeholders, the current situation is best understood not as a sudden disruption, but as a defined procedural checkpoint requiring timely, evidence-based action. Preparedness hinges on documentation accuracy, lab coordination, and clarity on official interpretation—not on technical redesign.

Source: Official notice jointly issued by Vietnam’s Ministry of Industry and Trade (MOIT) and the General Department of Standards, Metrology and Quality (STAMEQ), dated May 6, 2026.
Note: Enforcement details—including accepted lab accreditation scopes, appeal procedures for rejected submissions, and potential extensions—remain pending official clarification and are subject to ongoing observation.