Vietnam Tightens ESS Import Rules: UL 1973 TRP Test Mandatory for C&I Systems

Vietnam’s Ministry of Industry and Trade (MOIT) issued Technical Circular No. 32/TB-BCT on May 7, 2026, mandating UL 1973 Section 7.3 thermal runaway propagation (TRP) testing for all imported commercial and industrial (C&I)-grade energy storage systems (ESS), effective June 1, 2026. This development directly affects ESS manufacturers, importers, system integrators, and certification service providers engaged in the Vietnamese market — signaling a material escalation in technical compliance requirements beyond prior UL 9540A system-level evaluation.

Event Overview

On May 7, 2026, Vietnam’s Ministry of Industry and Trade (MOIT) published Technical Circular No. 32/TB-BCT. The circular stipulates that, starting June 1, 2026, all imported C&I-grade energy storage systems must undergo mandatory thermal runaway propagation (TRP) testing per UL 1973 Section 7.3. Previously, only UL 9540A system-level fire propagation testing was required. The new requirement extends verification to the cell and module level, introducing a more granular and technically demanding layer of conformity assessment.

Industries Affected

ESS Exporters & Importers

Exporters and importers of C&I-grade ESS into Vietnam will face extended lead times and higher pre-shipment compliance costs. Because TRP testing under UL 1973 is performed at the cell and module level — not just at the full system level — documentation and test reports must now reflect multi-tier validation. This may delay customs clearance if test data lacks traceability to specific production batches or configurations.

Cell & Module Manufacturers

Manufacturers supplying cells or modules integrated into C&I ESS destined for Vietnam must ensure their products are explicitly tested and certified for TRP per UL 1973 Section 7.3. Unlike UL 9540A, which evaluates assembled systems, UL 1973 TRP applies to individual electrochemical components and their arrangements. This implies potential redesigns or additional qualification cycles for certain chemistries or packaging formats.

System Integrators & OEMs

Integrators assembling C&I ESS using third-party cells/modules must now verify upstream TRP compliance — not merely rely on system-level UL 9540A reports. Failure to align module-level TRP performance with system architecture (e.g., spacing, thermal barriers, venting paths) may invalidate downstream certification. Integration workflows must incorporate TRP-specific design validation checkpoints.

Certification & Testing Service Providers

Laboratories accredited for UL 1973 testing — particularly those with capability for TRP under Section 7.3 — are likely to see increased demand from exporters preparing for Vietnamese market entry. However, capacity constraints and regional accreditation gaps may limit turnaround; providers must confirm MOIT recognition status of their TRP test reports before submission.

What Enterprises and Practitioners Should Focus On

Monitor MOIT’s official implementation guidance

The circular (No. 32/TB-BCT) references UL 1973 but does not specify whether MOIT accepts test reports from non-Vietnamese-accredited labs or requires local witnessing. Enterprises should track MOIT’s subsequent notices or Q&A documents for clarification on report validity, sample selection criteria, and acceptable deviations.

Verify TRP coverage across product tiers — not just final systems

Current UL 9540A reports do not satisfy the new requirement. Companies must audit existing certifications to identify which cell types, module designs, and BMS configurations have undergone UL 1973 Section 7.3 TRP testing — and whether such testing covers the exact variants intended for Vietnamese shipment.

Distinguish between policy issuance and operational enforcement

While the rule takes effect June 1, 2026, customs authorities may apply transitional allowances during initial rollout. Enterprises should not assume immediate full enforcement but must treat the June 1 date as the definitive compliance deadline for new shipments — avoiding reliance on informal grace periods.

Update procurement and supply chain documentation protocols

Procurement contracts with cell/module suppliers should now explicitly require UL 1973 TRP test reports, including test date, lab accreditation details, and configuration scope. Internal documentation systems must support version-controlled traceability from component test reports to final ESS declarations submitted to Vietnamese customs.

Editorial Perspective / Industry Observation

Observably, this regulatory update reflects Vietnam’s shift toward preemptive safety governance for grid-connected ESS — moving beyond post-integration behavior (UL 9540A) to intrinsic cell-level failure containment. Analysis shows the TRP mandate is less about immediate market restriction and more about signaling long-term technical expectations: future Vietnamese standards may harmonize with IEC 62933-4-2 or draft ASEAN-wide ESS safety frameworks. From an industry perspective, it functions primarily as a forward-looking signal — one that rewards proactive alignment with international cell-level safety benchmarks, rather than reacting to ad hoc compliance demands.

Consequently, the measure is better understood not as an isolated barrier, but as an early indicator of tightening regional convergence around electrochemical safety fundamentals — especially for markets scaling up utility-scale and commercial behind-the-meter deployments.

Conclusion

This MOIT circular marks a meaningful step in Vietnam’s technical regulation of energy storage imports. Its significance lies not in immediate disruption, but in its articulation of a higher baseline for cell- and module-level safety assurance. For stakeholders, the most rational interpretation is that UL 1973 TRP compliance is now a structural prerequisite — not a situational add-on — for sustained access to Vietnam’s growing C&I ESS market.

Information Sources

Main source: Vietnam Ministry of Industry and Trade (MOIT), Technical Circular No. 32/TB-BCT, issued May 7, 2026. Ongoing implementation details — including laboratory recognition procedures and transitional provisions — remain subject to further official notice and require continuous monitoring.