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APS activates giant batteries at Arizona solar facilities to release power after sunset


A network of solar generating stations has been sending electricity to Arizona Public Service Co. and its customers for the past decade. Now, the company is storing more of that power during the day for release at peak-demand evening hours when the sun is no longer shining.

APS said it recently activated giant batteries at nine solar-panel locations for night use through the heat wave this summer. Most of the nine locations are located west of Phoenix, taking advantage of prime solar availability in southwestern Arizona, said Ben Cluff, APS’ director of renewable resources.

The program, dubbed “Solar after Sunset,” helps to balance the electrical system and improve its resilience and reliability. APS said it has incorporated an array of safety recommendations after a fire and explosion at a battery facility in Surprise in 2019 that seriously injured four first responders.

Releasing solar power at night

The new systems absorb solar energy during the day and discharge it during high-demand periods later. The systems contributed power during the recent record stretch of high temperatures and record-shattering demand placed on APS, Salt River Project and other electric utilities.

“We just came through the worst heat wave in Phoenix history, delivering reliable electricity, and now we are serving our customers with this exciting new technology,” Cluff said.

The nine locations can provide 200 megawatts of power, enough to serve 32,000 Arizona homes for three to four hours. The company also plans to purchase power from 13 other energy storage systems located in Arizona over the next couple of years.

That additional solar generation and battery release will bring another 2,246 megawatts to the grid, supplying another 359,360 homes. APS estimates one megawatt can power, on average, about 160 homes.

Explosion leads to safety changes

APS said its energy-storage facilities are being built and operated with safety as a top concern. The company delayed these projects after the fire and explosion in Surprise.

The company implemented an array of safety measures after a two-year investigation. The new policies include much closer communication with and training of first responders, including more than a dozen fire departments around the state monitoring the new systems.

Of the seven systems west of Phoenix, one is near Buckeye, three are located in or near Gila Bend, two are in Hyder and one is in Yuma.

APS also has a battery storage facility north of Prescott and one in Red Rock, north of Tucson. Of these, the Red Rock facility has the highest generating capacity, followed by the location in Yuma and one in Gila Bend.

Reach the writer at [email protected].


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