Applications: Stationary Energy Storage

Notable Advancements in Codes and Standards for 2025 2026 NFPA 8551,2

General requirements applicable to all ESS now found in exclusively in Chapter 4. Emergent battery chemistries have been included, formerly falling into the “Otherˮ category. Lead-acid, aqueous nickel-based, and aqueous metal-air batteries now have consistent exclusions throughout. Exclusions have been added to Chapter 14 to allow for temporary storage of Li-Ion batteries under certain conditions. New requirements for emergency response plans, EV charging systems with integrated ESS, flow batteries, and ESS on barges. Annex Section G.8 has been revised to aid in evaluating the potential consequences of an explosion event. Decouples UL 9540A Edition 5 and prior) from Large-Scale Fire Testing. Both are now required for the reduction of prescriptive sizing and spacing - in response to concerns that prior large-scale test requirements and hazard analyses did not consistently capture realistic multi-enclosure failure scenarios and emerging ESS technologies.

2026 National Electrical Code3,4

Sizing guidance clarified for behind the meter ESS, providing for more consistent interpretation and application. Allowances for Power Control Systems PCS) to manage current flow and provide inherent overcurrent protection. Expanded guidance on bidirectional power and grid integration

UL 9540, Edition 3 redlines published in 20255,6

New product certifications after the effective date of September 2024 must comply with Edition 3. Significant update to introduce clear definitions and marking requirements for both AC ESS and DC ESS. Each component in an ESS is now more appropriately defined by its function, rather than physical location.

UL 3601 and UL 1974 represent an emerging focus on battery lifecycle and circularity

UL 3601 Edition 1 published in July 2025 establishes a framework for measuring and reporting on the sustainability of Li-ion and other secondary batteries. In parallel, UL Solutions now offers an ECOLOGO® Certification fro Circularity of Batteries.7,8 UL 1974 Edition 2, first published in November of 2023 is currently in active status with several changes being proposed. Provides a path for repurposing EV batteries in less-demanding stationary storage applications.9

Taken in aggregate, these changes highlight near-term stabilization in safety-related ESS codes and standards, while also demonstrating an industry shift towards maturity and sustainability.

Source: NFPA 855, 2026 Edition, Meyfire Blog, NFPA 70, 2026 Edition, IAEI Magazine, UL Standards and Engagement, Sustainable Energy Action Committee SEAC, UL 3601, Edition 1, UL Solutions UL, LLC, UL 1974 Creating a Safe Second Life for Electric Vehicle Batteries

Extracted from the PDF; charts and images may read imperfectly.