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​april 26, 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, and firefighters who responded to the call were transported to area hospitals. An investigation with APS, first-responder representatives, 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. Our hearts go out to the firefighters injured in the line of duty. Their health, safety and recovery are our top priorities. 
investigation underway 
An investigation with APS, first-responder representatives and third-party engineering and safety experts is underway. What we know at this point is that we had an equipment failure. A thorough investigation will help us determine what exactly failed and why.
lessons to be learned 
Importantly, until the investigation is completed, we cannot speculate about the root cause of the incidentwhether it was the battery unit itself or another grid component. 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. It is too early to know when we will complete the investigation, but we will act quickly to apply the safety lessons learned from this incident. 
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. 
additional resources