Core Viewpoint - The new UL 9540A sixth edition introduces stricter compliance requirements for battery energy storage systems (BESS), marking a shift from optional large-scale fire testing (LSFT) to a critical compliance step, significantly impacting design and cost for manufacturers [10][11]. Regulatory Changes - The new regulations signal the end of the "wild growth" phase for the energy storage industry, as stricter compliance measures are being implemented, including the introduction of GB/T 51048-2025 and the UL 9540A sixth edition [2][3]. - The sixth edition of UL 9540A incorporates mandatory hardware design constraints, moving beyond just testing to include how systems are constructed [3][5]. Testing Standards - The sixth edition introduces significant changes in testing standards, including the requirement for LSFT to be conducted at the installation level, focusing on extreme conditions and the recording of critical data such as fire spread and toxic gas release [5][7]. - The testing now requires that even if the target cabinet does not catch fire, any failure in temperature control leading to venting will result in a failed test, emphasizing the need for enhanced safety measures [7][9]. Cost Implications - Compliance with the new standards is expected to increase certification costs significantly, with estimates ranging from $500,000 to $2 million for a single LSFT, including various associated costs [11][12]. - The financial burden of re-testing and redesigning after a failed test could add an additional 50% to 100% to initial budgets, making it crucial for manufacturers to ensure first-time success [11][12]. Industry Impact - Major companies in the energy storage sector, such as BYD and Huawei, have already begun conducting LSFTs in anticipation of the new regulations, indicating a proactive approach to compliance [12][13]. - The UL 9540A sixth edition is expected to influence not only the North American market but also projects in Australia and Europe, potentially becoming a prerequisite for market entry in China [11][12].