Case Study: Penske Truck Leasing achieves 40% site peak energy reduction and optimized EV fleet charging with Stem’s Athena energy storage solution

Piloting Battery Storage for EV Fleet Charging

Penske Truck Leasing piloted a battery energy storage system (BESS) at its Ontario, CA EV fleet charging depot to address the operational and investment challenges of California’s transition to zero‑emission heavy‑duty trucks. The project, funded in part by SCAQMD and the ports and developed with partners including Stem, sought a reliable software solution after the original provider struggled to optimize the battery; Penske turned to Stem’s Athena® smart energy software to improve charging outcomes.

Stem provided a turnkey solution—installing a 350 kW / 800 kWh energy storage system and deploying Athena® to model tariffs, optimize EV charging in real time, and ensure SGIP‑compliant GHG reductions. The Stem system reduced Penske’s site peak energy consumption by 40%, restored project value through revenue‑maximizing optimization, and is guiding Penske’s long‑term fleetwide EV charging strategy.

Penske Truck Leasing

Sean Yentsch

Vice President Facilities