EPRI Battery Energy Storage Systems (BESS) Failure Incident Database

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The database captures incidents occurring globally and cites information from publicly available sources, including media reports, published root cause analyses (RCA), and corporate press releases. Source documents are identified by active searching of global English-language media, and passive collection of reports through keyword flagging on internet websites and RSS feeds. Crowdsourced information that can be verified through publicly available documenta- tion is also incorporated. EPRI has used academic publica- tions, and collaborated with other organizations tracking failures, to ensure all publicly known stationary BESS events are captured. However, many incidents are not reported
in news media, especially before 2018-19 when there was
a renewed industry focus on safety. There is no guarantee that the database captures every relevant BESS failure incident, nor that all project data related to an incident
is captured. Despite these caveats, this remains the most comprehensive stationary BESS failure database available.
Data Collection
At the time of writing, the database contained 81 incidents. Of these, 26 incidents had sufficient information to assign
a root cause and to identify the element that experienced failure. Certain incidents had published root cause analy- sis reports that explicitly noted the cause of failure. The remaining incidents were classified based on engineering judgement by subject matter experts at EPRI, TWAICE, and Pacific Northwest National Laboratory (PNNL). The authors reviewed publicly available technical details and inter- viewed other industry experts involved in failure incident analysis. No proprietary information was discussed in these interviews nor used in the classification of the incidents.
Transparency on the cause of BESS failures continues to be limited. Battery OEMs and BESS integrators are often reluc- tant to disclose the cause of failure, and many investigation reports are not released to the public. In several instances, legal complications prevent site owners or manufacturers from divulging information about the nature of the fail- ure. Aggregation and anonymization by a third-party can encourage disclosure of such information to support safety research advancement.
Classification of Failure Incidents
Incidents can result from a variety of causes, such as water intrusion, retrofitting errors, operating conditions, cool- ant leaks, temperature stress, quality control, component manufacturing defects and other factors. For meaningful analysis, these causes were grouped into classifications. Each failure incident with sufficient information was clas- sified by root cause and by failed element. Definitions for each classification are provided below:
Root Cause:
• Design
A failure due to planned architecture, layout, or func- tioning of the individual components or the energy storage system as a whole. Design failures include those due to a fundamental product flaw or lack of safeguards against reasonably foreseen misuse.
• Manufacturing
A failure due to a defect in an element of an energy storage system introduced in the manufacturing pro- cess, including but not limited to, the introduction of foreign material into cells, forming to incorrect physical tolerances, or missing or misassembled parts.
• Integration, Assembly & Construction
A failure due to poor integration, component incompat- ibility, incorrect installation of elements of an energy storage system or due to inadequate commissioning procedures.
• Operation
A failure due to the charge, discharge, and rest behav- ior of the energy storage system exceeding the design tolerances of an element of an energy storage system or the system as a whole. Operational failures include, but are not limited to, incorrect sensing of voltage, current, temperature, and other set point values, or operation above designed temperature, C-rate, state of charge, or voltage limits of the energy storage system.
Failed Element:
•
6
Cell/Module
A failure originating in the lithium ion cell or battery module, the basic functional unit of the energy stor- age system. It consists of an assembly of electrodes, electrolyte, casing, terminal, and usually separators.6
IEC Glossary. https://www.electropedia.org/iev/iev.nsf/display?openf orm&ievref=482-01-01.
4 | EPRI White Paper
15256168
May 2024