By: Jim Green, Manager, Global Energy Storage

Deployments of energy storage systems (ESS) in the U.S. are anticipated to nearly triple this year, thanks to the multiple value streams the systems provide, a reduction in cost, and favorable state policies.

ESS offer many benefits by helping residential, commercial/industrial, utility, and community users to more effectively manage electricity supply and use. These scalable and flexible systems can store and release electricity on demand, integrate renewable energy sources, provide backup power, and increase power quality. This wide variety of applications and system configurations lead to an equally wide variety of compliance requirements from the component to the system level across North America.

In addition, ESS development and installation involves many stakeholders – from component suppliers to battery and inverter manufacturers, system owner/operators, testing/certification organizations, and regulatory authorities. This creates a complicated landscape of constantly evolving safety requirements that must be navigated for a successful project launch.

Compliance by Market Segment

Ultimately, safety of energy storage systems is a shared responsibility and requires project owners and manufacturers to meet a broad array of requirements. A brief summary of some of the most important requirements in North America are shown in Table 1.

In addition, compliance methods differ by market segment. Residential systems, for example, typically require a certification mark from a Nationally Recognized Testing Laboratory (NRTL) such as CSA Group, while commercial or industrial systems have to follow requirements dictated by local Authorities Having Jurisdictions (AHJs) and ensure components are certified. Depending on the system and the requirements of the AHJ, they will either follow the model certification procedure or go through a field evaluation. The field evaluation process provides additional review of a unique or low volume system in the field and results in a special label for the specific installation. Often, both certification of the system and its components and a field evaluation may be necessary when final system integration takes place in the field.

Evolving Standards and Codes for ESS

1) ANSI/CAN/UL-1973 – Standard for Batteries for Use in Stationary, Vehicle Auxiliary Power and Light Electric Rail (LER) Applications

The 2018 edition of this bi-national safety standard covers cells, modules, and battery systems used in stationary applications. It includes specific safety criteria for well-known battery chemistries as well as construction and testing criteria. The standard is typically used in product testing and certification for storage battery evaluation in North America.

2) UL/CAN 9540 – Standard for Energy Storage Systems and Equipment

This bi-national standard applies broad requirements for all types of ESS, including stationary ESS connected to the power grid. It also sets standards for specific functional safety measures, including safety analysis and safety-related electrical and electronic controls. Electrical, mechanical, and environmental tests are included, as well as measures to evaluate inherent system design and performance, and how the system interfaces with infrastructure.

3) UL 9540A – Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems

UL 9540A offers a test method for evaluating thermal runaway propogation in battery ESS. Referenced in the draft National Fire Protection Association (NFPA) 855 standard, it aims to provide quantitative data to characterize potential fire events in ESS. Testing is to be done at the cell, module, unit, and possibly the installation level. UL is expecting to take this to the Standards Technical Panel (STP) process later this year, in order to begin to build industry consensus on the test procedure.

4) NFPA 855 – Standard for the Installation of Stationary Energy Storage Systems

NFPA 855, which is expected to be published in 2019, outlines the requirements for installing stationary ESS. It covers lead acid and Ni-Cd systems greater than 70 kWh, lithium-ion and sodium systems greater than 20 kWh, and other systems greater than 10 kWh, all of which must be listed to UL 9540. The standard specifies minimum water fire suppression rates, or allows for alternate fire suppression if large scale testing is conducted. It also sets size and separation requirements.

Emerging Compliance Issues

As ESS technology and usage evolve, new compliance issues arise. In the standards field, this is resulting in an increase of requirements in the National Electrical Code and a resulting increase in certification requirements for standards such as UL 1973 and UL 9540. It is also driving the development of new codes, standards, and test methods such as UL 9450A and NFPA 855 mentioned above, as well as IEC 62932 for flow battery systems, IEC 62933 for ESS, and UL 1974 for repurposed batteries.

Issues are also being raised regarding ESS software, especially regarding its ability to provide critical safety functions and its overall security posture – making cybersecurity evaluation an increasingly critical task in preparing ESS for market entry, as with any “connected” technology being used in the energy sector. Increasing digitization in energy has created opportunities for hackers that have not been fully explored, so utilities and other industry players must be – and are – focused on upping their cybersecurity measures to prevent potential attacks.[2]

Navigating these Challenges with CSA Group

As a leader in standards development and performance & safety testing of battery and energy storage systems in North America, and an expert in functional safety and cybersecurity evaluation, CSA Group can help ESS stakeholders meet their applicable requirements for safety and security through the entire product development lifecycle.

[1] GTM Research and Energy Storage Association, U.S. Energy Storage Monitor: Q1 2018, cited in Groom, Michael “U.S. energy storage market to nearly triple this year: report.” Thompson Reuters, March 6, 2018.

[2] Jason Deign (October 9, 2017), “Energy Sector Ups Cybersecurity Amid Growing IT Threats,” in Greentech Media. Retrieved from: http://www.greentechmedia.com/articles/read/energy-sector-ups-cyber-security-amid-growing-it-threats#gs.wAp2m6I