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​august 7, 2019  
equipment failure at mcmicken battery facility 
Around 5 p.m. on April 19, there were reports of smoke from the battery system at APS’s McMicken site in Surprise, Arizona. Hazardous Material units and first responders arrived on scene to secure the area. For reasons still unknown, the system subsequently experienced a catastrophic failure, resulting in injured first responders who were transported to area hospitals. An investigation led by APS, first-responder representatives, the system integrator, manufacturers and third-party engineering and safety experts is underway to determine the cause of the incident.
first responders 
We greatly appreciate the hard work and bravery of the first responders who were involved. While the recovery of the first responders injured on scene during the incident remains top of mind for all involved with the investigation, their progress and status will not be included in these updates. 
investigation underway 
The timeline to complete the investigation is still uncertain, but periodic updates will be posted here to report on the process and progress being made. Until the investigation is completed, the parties involved cannot speculate about the cause of the incident.
lessons to be learned 
APS and the investigation team intend to share what they can of the ultimate findings, especially to the extent they are helpful to the industry and response agencies. What we do know is that energy storage, including batteries, is vital to a clean-energy future. This technology is solving important challenges and creating new opportunities for clean energy like solar. The investigation will help us learn all we can from what happened so that we can apply those lessons to how we move ahead. 
mcmicken battery facts 
  • Location: Surprise, Arizona, near the APS McMicken substation (28 miles northwest of downtown Phoenix)
  • Technology: Lithium-ion battery
  • Capacity: 2 megawatts/2 megawatt-hours
  • System integrator: Fluence
  • In-service date: March 2017
  • Primary functions: Integrating solar energy resources in an area with high rooftop solar penetration, and grid services including voltage regulation and power quality. 
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