Work Begins in 2025 on Tucson Electric Power’s Largest Solar Battery Plus System
Construction will begin in January to expand the largest solar plus storage system in Tucson Electric Power’s growing clean energy portfolio.
Wilmot Energy Center II will include a 100-megawatt solar array and a 100 MW, four-hour lithium-ion battery energy storage system. The additions will double the generating capacity and more than quadruple the storage capacity on the site, located south of the Tucson International Airport near South Wilmot and East Sahuarita Road.
The system’s photovoltaic panels will be mounted on a single axis tracking system that allows them to follow the sun’s position in the sky to maximize production. The new battery system will be able to store 400 megawatt hours of energy, enough to serve approximately 14,600 homes for four hours.
The existing Wilmot Energy Center includes 100 MW of solar generation and 30 MW of two-hour storage. An affiliate of NextEra Energy Resources owns and operates that system for TEP and will do the same for the new resources, which should come online in 2027.
“We continue to make significant progress toward our goals by expanding the clean energy resources that provide reliable service to our customers,” said Erik Bakken, TEP Senior Vice President of Energy Resources and Chief Sustainability Officer. “With more energy storage systems, we can deliver more clean energy to customers when they need it most.”
Wilmot II will advance TEP’s efforts to expand clean energy resources as we work toward achieving net zero carbon emissions by 2050.
TEP’s 200 MW Roadrunner Reserve battery energy storage system in southeast Tucson is under construction. That system will be its largest energy storage resource and one of the largest in Arizona when it begins operation in summer 2025. A second 200-MW battery system at the same location – Roadrunner Reserve II – is scheduled to begin operation in early 2026.
Winchester Solar, located in Cochise County, will include an 80-MW solar and 80-MW battery energy storage system. The system will produce enough energy each year to serve the annual energy needs of about 11,000 homes. The 320 megawatt-hour battery system can provide 80 MW of energy for four hours when fully charged. The system is expected to come online in 2027.
Battery systems help TEP and other utilities make better use of wind and solar resources by “shifting” their output to periods of greatest need. They also can help smooth out imbalances throughout the day as clouds block the sun or wind patterns shift. Currently, TEP has 51 MW of energy storage capacity.
Wilmot II was selected through an all-source request for proposals issued in 2022. This process identifies the most cost-effective project among competing proposals that satisfy certain energy requirements. TEP and sister company UniSource Energy Services are currently evaluating proposals submitted in response to the 2024 all source request for proposals.
Projects selected through this process align with our long-term integrated resource plans, which describe how each company plans to meet customers’ increasing energy needs over the next 15 years while maintaining affordable service.
About 20% of TEP’s power came from its clean energy resources in 2023.
