Fire Hazard and Risk Assessment Battery Energy Storage System (BESS)

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Fisher Engineering, Inc. Energy Safety Response Group actively participating in the steering committee, this helped ensure that from the outset communication was
timely, efficient, well-coordinated across different organizations and accurate.
In addition to the community outreach, Neoen and Tesla also briefed multiple industry, State and Federal Government Departments and Agencies immediately following the VBB fire and at the conclusion of the investigation process. These briefings helped ensure the wider energy sector with interests in BESS were able to be kept directly informed as information became available.
Overhaul and Remediation
On July 29, 2021 nearly half of the Megapacks had been installed and the site was in the testing and
commissioning stage of the project. Following the fire event on July 30, 2021, fire department personnel,
regulatory agencies and other emergency responders remained on-site for precautionary purposes until
August 2, 2021. At that time the site was turned over for regulatory fire investigations to begin. On-site fire
investigations started on August 3, 2021 and continued until August 12, 2021. During this time, starting on
August 6, 2021, the site was permitted to continue the installation of Megapacks while the area around MP-1
remained cordoned off for the investigation. On September 23rd, 2021, less than two months after the
fire, VBB was re-energized and testing and commissioning restarted. Remediation of the damaged equipment
followed shortly after, and lasted a total of three days. All testing and commissioning efforts were
completed without any further incidents and on December 8, 2021, VBB
officially opened.
Lessons Learned
The VBB fire exposed a number of unlikely factors that, when combined, contributed to the fire initiation as well as its propagation to a neighboring unit. This collection of factors had never before been encountered during previous Megapack installations, operation and/or regulatory product testing. This section summarizes those factors as well as the emergency response to the fire, discusses the lessons learned from this fire event, and highlights the mitigations Tesla has implemented in response.
1. Commissioning Procedures
Lessons learned related to commissioning procedures include: (1) limited supervision/monitoring of telemetry data during the first 24 hours of commissioning and (2) the use of the keylock switch during commissioning and testing. These two factors prevented MP-1 from transmitting telemetry data (internal temperatures, fault alarms, etc.) to Tesla’s control facility and placed critical electrical fault safety devices (such as the pyro disconnect) in a state of limited functionality, reducing the Megapack’s ability to actively monitor and interrupt electrical fault conditions prior to them escalating into a fire event.
Since the VBB fire, Tesla has modified their commissioning procedures to reduce the telemetry setup connection time for new Megapacks from 24 hours to 1 hour and to avoid utilizing the Megapack’s keylock switch unless the unit is actively being serviced.
2. Electrical Fault Protection Devices
Lessons learned related to electrical fault protection devices include: (1) coolant leak alarms; (2) the pyro disconnect being unable to interrupt fault currents when the Megapack is off via the keylock switch and (3) the pyro disconnect likely being disabled due to a power supply loss to the circuit that actuates it. These three factors prevented the pyro disconnect of MP-1 from actively monitoring and interrupting the electrical fault conditions before escalating into a fire event.
Report of Technical Findings: Page 9 Victorian Big Battery Fire 1/25/2022