Tucson Electric Power’s largest battery energy storage system will be up and running soon – storing lower-cost energy during the day to help satisfy energy needs through hot summer afternoons and evenings.
TEP’s 200-megawatt (MW) Roadrunner Reserve system will store 800 megawatt hours of energy, enough to serve approximately 42,000 homes for four hours when deploying at full capacity. The system, which is expected to start providing service for TEP customers this month, will be the largest energy storage resource in TEP’s portfolio.
TEP expects to charge the grid-connected batteries in the morning and early afternoon, when solar energy is abundant and costs less to purchase. Stored energy will be delivered later in the day when energy use typically is at its highest. By leveraging lower-priced market power to offset higher cost generation, TEP estimates that the project will reduce fuel and purchased power costs by $25 million from June 2025 through September 2026.
“Roadrunner Reserve will allow us to provide reliable, affordable service to our customers when they need it most,” said Eric Bronner, Vice President of Energy Management, Planning and Development. “This new energy system will also protect customers from fuel price volatility and help keep rates more stable over time.”
Roadrunner Reserve is the latest addition to a balanced mix of resources, including solar and wind, that support a cleaner energy future. TEP invested about $350 million in the system, which was built next to a southeast side TEP substation.
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, reducing the amount of clean energy produced by renewable resources. In addition to Roadrunner Reserve, TEP has about 50 MW of energy storage capacity.
Construction has begun on a 200 MW expansion of Roadrunner Reserve that will begin operations in 2026.
Roadrunner Reserve is being designed and built for TEP by Scottsdale-based DEPCOM Power, Inc. It employs lithium iron phosphate battery units, a newer technology that offers longer life and safer operation than other types of battery systems.
The system supports TEP’s plan to meet future energy demand with a balanced portfolio of wind, solar and natural gas generation, as well as energy storage systems. Our 2023 Integrated Resource Plan also sets our aspirational goal of achieving net zero direct greenhouse gas emissions by 2050.
TEP has signed several other agreements for new clean energy resources, including:
- Babacomari Solar, a 160 MW solar project in Cochise County coming online in 2026.
- Wilmot Energy Center expansion, a 100 MW solar and 100 MW battery energy storage system coming online in 2026.
- Winchester Solar, an 80 MW solar and 80 MW battery energy storage system coming online in 2027.
