^{Arizona Governor Katie Hobbs tours Roadrunner Reserve I during a ribbon-cutting ceremony in November.}

Tucson Electric Power (TEP) has officially put into service one of Arizona’s largest battery energy storage systems. The 200-megawatt system, called Roadrunner Reserve I, can power 42,000 homes for up to four hours when deployed at full capacity.

Storing solar energy for use during peak demand not only helps maintain service during extreme conditions, but it also supports deployment of lower cost energy. TEP plans 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 is typically at its highest.

“Roadrunner Reserve 1 represents a strategic investment designed to strengthen energy resilience and reliability, while advancing TEP’s commitment to achieving its clean energy objectives,” said Jim Reid, Executive Vice President, Sustainability and Chief Legal Officer, Fortis Inc.

This $350 million project proved its value during record-breaking heat in August, when energy demand reached an all-time high. Roadrunner Reserve helped keep homes cool and supported grid stability during the summer’s hottest days.

Erik Bakken, Senior Vice President and Chief Administrative Officer, TEP, explained, “Not everyone has the resources to install solar panels or manage their own private battery system. That’s why we’re investing in large-scale solutions like this one — to benefit all of our customers, every day.”

A second 200 MW system is expected to be in service by summer 2026, doubling storage capacity.

Learn more: TEP Celebrates Launch of Roadrunner Reserve with Governor Hobbs and Local Leaders – Tucson Electric Power