Safety testing and certification for energy storage systems (ESS)
Large batteries present unique safety considerations because they contain high levels of energy. Additionally, they may utilize hazardous materials and moving parts.
We work hand in hand with system integrators and OEMs to better understand and address these issues.
Understanding UL 9540 and ESS certification
UL 9540, the Standard for Energy Storage Systems and Equipment, covers electrical, electrochemical, mechanical and other types of energy storage technologies for systems intended to supply electrical energy. The Standard covers a comprehensive review of ESS, including charging and discharging, protection, control, communication between devices, fluids movement and other aspects.
UL 9540 provides a basis for safety of energy storage systems that includes reference to critical technology safety standards and codes, such as:
- IEEE 1547 and 1547.1
- CSA FC1
- NFPA 70
- NFPA 2
- ASME Boiler and Pressure Vessel Code
- ASME B31 piping codes
The standard includes additional criteria to address materials, enclosures, including walk-in enclosures, controls, piping, utility grid interaction, and special purpose interactive systems, hazardous moving parts, signage and instructions.
If successful, ESS certification can be achieved by evaluation of off-the-shelf components that are put together by the manufacturer or integrator and submitted for certification.
ESS performance and reliability testing
We also offer performance and reliability testing, including capacity claims, charge and discharge cycling, overcharge abilities, environmental and altitude simulation, and combined temperature cycling and vibration testing.
We offer performance testing to standards such as:
- IEC 61960
- IEC 60068 series
- IEC 62933-1-1
- IEC 62933-5-2
- NEMA 80057-2024 (formerly NEMA ESS 1)
Our key services for battery energy storage system (BESS) applications
Testing for safety compliance requirements
We help you meet legislation and market access requirements set by countries across North America, South America, Europe and Asia.
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Testing for global safety and performance requirements
We are deeply knowledgeable about SAE, IEC, UN and UL Standards.
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Performance and reliability testing
We help demonstrate how your products will perform under anticipated usage and various hazardous scenarios — including abuse — during discharge and recharge cycles. We offer custom research and testing services, witness testing and field evaluations.
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Regulatory and code compliance support services
Our seasoned experts can answer questions about the code requirements that may affect your products. We also offer code review services that utilize our expertise in codes to provide technical opinions on requirements that impact product design and installation.
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Our BESS services by application
- Commercial and industrial battery energy storage systems
- Residential battery energy storage systems
- Utility-scale energy storage systems
- Uninterruptible power supply (UPS)
- Electric vehicle charging equipment
Our BESS services by safety standard
UL 9540, The Standard for Energy Storage Systems and Equipment
Covers electrical, electrochemical, mechanical and other types of energy storage technologies for systems intended to supply electrical energy.
UL 9540A, The Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems
Explicitly cited in NFPA 855 for large-scale fire testing and is the only national standard in the U.S. and Canada for fire safety testing methods for battery ESS.
UL 1973, The Standard for Batteries for Use in Stationary and Motive Auxiliary Power Applications.
UL 9540B, The Outline of Investigation for Large-Scale Fire Test for Residential Battery Energy Storage Systems
Addresses additional risks and considerations around safety for residential use.
UL 3202, The Standard for Safety for Mobile Electric Vehicle Charging Systems Integrated with Energy Storage Systems
UN/DOT 38.3
United Nations (UN) Manual of Tests and Criteria, Lithium Metal, Lithium-Ion and Sodium-Ion Batteries.
On-demand webinar
Introduction to Revisions of UL 9540A:2025
Explore the latest UL 9540A:2025 updates on thermal runaway testing for battery energy storage systems (BESS) with expert insights from UL Solutions.
Who can benefit from BESS services?
ESS manufacturers
ESS manufacturers can benefit from testing and certification services for ESS standards and codes. We also offer performance and reliability testing, including capacity claims, charge and discharge cycling, overcharge abilities, environmental and altitude simulation, and combined temperature cycling and vibration testing.
Unit assemblers and system integrators
Unit assemblers and system integrators can benefit from our comprehensive field evaluations that can help you demonstrate the compliance of an ESS installation to code authorities, owners and regulatory bodies.
Installers
Installers can benefit from our field services that bring compliance expertise to you to help address the safety and performance of equipment and systems as during or upon installation.
Module and pack manufacturers
Module and pack manufacturers can benefit from electrical, mechanical and environmental testing to evaluate the ability of large batteries to safely withstand simulated abuse conditions based on your specified charge and discharge parameters.
Cell manufacturers
Cell manufacturers can benefit from battery cell certification services that test to all applicable industry standards to help demonstrate the performance, reliability and safety of battery cells used in an increasing number of products.
Marking for ESS
Depending on the applicability of the system, different standards need to be met before you can get your products into different installations and markets. For example, depending on the area of Europe the product will be installed, you may need:
- CE marking and CE self-declaration for all Europe except the United Kingdom
- UKCA marking and UKCA self-declaration for Great Britain (as of January 1, 2021)
- UKNI Marking and UKNI self-declaration for Northern Ireland (as of January 1, 2021)
For any of the marking processes listed above, your system must meet the following requirements:
Safety requirements for Marking and self-declaration
- Low Voltage 2014/35/UE
- UK Legislation; Electrical Equipment (Safety) Regulations 2016
EMC requirements for Marking and self-declaration
- Electromagnetic Compatibility 2014/30/UE
- UK Legislation; Electromagnetic Compatibility Regulations 2016
Custom research of energy storage systems
We conduct custom research to help identify and address the unique performance and safety issues associated with large energy storage systems. Research offerings include:
- Regulatory assessment services
- Simulation of fire suppression/containment system
- Full-scale energy storage system fire demos (for firefighter safety)
- Computer modeling and scaling
- Construction assessment
- Battery aging study
- Forensic analysis/failure investigation
- Fault Tree Analysis (FTA) of failure modes
- Internal short circuit/failure
- Smoke characterization
- Failure propagation
Why UL Solutions
When you partner with us, you will benefit from the demonstrated mastery in advancing battery technology and safety we have amassed in more than 35 years of battery testing. Our team of scientists, engineers and product specialists are committed to advancing battery technology and are actively involved in shaping industry standards, developing Outlines of Investigation and refining testing protocols.
Our experienced engineering and research teams can help you develop insights using our deep knowledge of battery chemistries and fire suppression formed by establishing and cultivating enduring partnerships with regulators and industry stakeholders. We are proud of our demonstrable track record of success serving organizations and entities such as fire departments and electrical and building inspectors.
Among our global network of facilities, six of our 80 laboratories specialize in battery cell, pack and module testing and feature flexible availability, with no need for subcontracting. Our staff of expert field engineers is ready to deliver on-site or witness testing services to support your market access across North America, South America, Europe and Asia.
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We work with system integrators and OEMs to better understand and address energy storage systems issues.
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