
Page | 001 Statement of Technical Findings Fire at the Victorian Big Battery Background On 30 July 2021, the Victorian Big Battery (VBB) experienced a fire that involved two Megapacks during commissioning. Once the CFA had brought the situation under control, it handed control of the site to Energy Safe Victoria (ESV). ESV then commenced an investigation into the incident to determine its root causes and what actions should be taken to prevent a recurrence. Neoen International SAS and its contractors UGL Engineering Pty Ltd and Tesla Motors Australia Pty Ltd (Tesla), who respectively own and operate the VBB site, have cooperated with ESV throughout its investigation. Methodology Two Megapacks (each being a shipping container size battery unit) were completely consumed by the fire. The most likely root cause was determined by Tesla’s engineering investigation and recreation of events to replicate real data from the incident in order to determine most likely the root cause. The following findings are informed by testing undertaken by Tesla, examination of the scene by ESV (and other Victorian agencies), video surveillance footage and telemetry data from the original incident. Root cause The most likely root cause of the incident was a leak within the Megapack cooling system that caused a short circuit that led to a fire in an electronic component. This resulted in heating that led to a thermal runaway and fire in an adjacent battery compartment within one Megapack, which spread to an adjacent second Megapack. Contributory factors A number of other factors contributed to this incident and the destruction of the entire Megapack. Had these contributory factors not been present, the initial fault would likely have been identified and either manually or automatically contained. • The supervisory control and data acquisition (SCADA) system for a Megapack took 24 hours to ‘map’ to the control system and provide full data functionality and oversight to operators. The Megapack that caught fire had been in service for 13 hours before being switched into an off-line mode when it was no longer required as part of the commissioning process. This prevented the receipt of alarms at the control facility. • A key lock was operated correctly to switch the Megapack to off-line service mode (which was no longer required for ongoing commissioning) but this caused: o telemetry systems for monitoring the condition of the (now out of service) Megapack to shut down and so remove visibility of the developing event o the battery cooling system to shut down o the battery protection system to shut down, including the high voltage controller (HVC) that could have operated a pyrotechnic fuse to disconnect the faulty battery unit. |