TUCSON, Ariz. (KGUN) — Tucson Electric Power has doubled the battery storage capacity at its Roadrunner Reserve facility, bringing the total to 400 megawatts—enough to power about 85,000 homes for four hours when fully charged.
TEP and DEPCOM Power executives joined Mayor Romero and other local leaders for a ribbon-cutting ceremony Tuesday morning to celebrate the expansion.
Roadrunner Reserve 1 came online last summer, giving TEP 200 megawatts of battery storage at this site.
The expansion adds a second battery storage unit, known as Roadrunner 2, to the existing facility. The batteries store energy earlier in the day when more solar power is available, then send that energy back to the grid later when temperatures and demand start climbing.
TEP spokesperson J.D. Wallace said Tucson's record-breaking heat shows exactly why that extra storage capacity is needed.
"Our record demand was last year in 2025 on August 6th when the temperature was 111 degrees, and that record demand was 2,502 megawatts. And at that time we had Roadrunner 1 online, and that helped us meet that demand."
Roadrunner 1 has 360 batteries and Roadrunner 2 has 244. Wallace said that is because more energy can be stored in each battery in Roadrunner 2.
Roadrunner Reserve has already been tested this summer. Wallace said when a transmission line went offline and more than 400 megawatts of power were suddenly needed, the facility was able to provide most of it.
Wallace also said the batteries can help control fuel costs by storing lower-priced energy and using it later when demand is higher.
Tucson Mayor Regina Romero said the expansion is especially important for vulnerable communities during extreme heat.
"If there's less power outages, especially with extreme heat, when AC systems and the electrical grid is really used heavily, people can stay in their home."
Romero said the expansion can help Tucsonans when they need it most—during extreme heat.
"Nowadays ACs are not a luxury, they're a need."
TEP says Roadrunner Reserve is not its last planned battery storage addition. Wallace said the utility has more projects in the pipeline.
"This doesn't stop with Roadrunner 2. We also have Winchester solar and battery energy storage scheduled to come online next year. That'll add another 80 megawatts of solar and 80 megawatts of battery storage."
This story was reported on-air by a journalist and has been converted to this platform with the assistance of AI. Our editorial team verifies all reporting on all platforms for fairness and accuracy.
——
Jacqueline Aguilar is a multimedia journalist at KGUN 9. Born and raised in Yuma, AZ., she is no stranger to the unforgiving Arizona heat. Now this U of A wildcat is excited to be back in Tucson and is looking forward to involving herself in the community. Share your story ideas with Jacqueline by emailing jacqueline.aguilar@kgun9.com or connecting on Facebook, Instagram or X.
