Science safety leader UL Solutions has announced a new certification pathway intended to help manufacturers of modular direct current (DC) battery energy storage systems (BESS).
Announced 20 October, the certification could help DC BESS manufacturers bring products to market with greater flexibility and clearer documentation for installation reviews.
The systems covered by the new pathway are often used for backup power at critical infrastructure sites and for grid-scale energy storage applications.
DC BESS can help reduce energy losses by limiting the number of times electricity must be converted between alternating current (AC) and DC, and can also simplify connections to solar panels, backup generators and other equipment.
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Many of these systems use a modular design that allows manufacturers to combine different components for individual projects. However, confirming that components work safely together can add complexity to certification and installation reviews.
The new certification programme offers manufacturers an alternative to seeking a full matched-assembly system listing from the outset. When a compatible subsystem is identified, the resulting certification documentation provides manufacturers, developers and code authorities with information about the evaluated configuration.
“Modular energy storage designs require a clear way to demonstrate how the system and its critical subsystems work together,” said Wesley Kwok, vice president and general manager of the Energy and Industrial Automation group at UL Solutions. “This certification programme gives manufacturers, developers and code authorities documented information about evaluated system combinations while supporting a more flexible approach to DC energy storage system design.”
Under the programme, UL Solutions evaluates the DC ESS together with each identified subsystem against the applicable requirements of UL 9540, the Standard for Energy Storage Systems and Equipment. The evaluation covers electrical, communication and interoperability aspects between the system and its evaluated subsystems.
Compatible subsystem models are documented in the UL Product iQ certification database under the DC ESS certification category, enabling code authorities to verify evaluated combinations.
UL 9540 testing covers electrical, electrochemical, mechanical and other aspects of energy storage technologies used in systems intended to supply electrical energy. Its evaluation framework includes charging and discharging, protection, controls, communication between devices, and other system-level considerations.
The certification pathway comes as DC block designs grow in popularity within the BESS market, with a trend towards larger, 5MWh-plus, 20-foot units driven largely by cost efficiencies, particularly on large-scale US projects.
Industry figures have noted that higher energy density within these DC blocks reduces the amount of rigging, anchor bolts, auxiliary connections and fire systems required per unit of capacity.
