Image: Tesla
A new $51 million Tesla Megapack battery energy storage system is now operational in Kingman, Arizona. Developed by Ameresco, Inc., the 50 MW/200 MWh installation is the largest behind-the-meter (BTM) battery project in Arizona and the fourth largest of its kind in the U.S.
The system supports the ongoing expansion of Nucor’s Kingman bar mill, which includes the addition of a new electric arc furnace aimed at boosting production capacity to 600,000 tons annually. “By placing a battery energy storage system onsite at Nucor’s Kingman plant, we are helping to support their expansion and create a more resilient, reliable and clean energy future,” said Jonathan Mancini, Senior Vice President of Solar & BESS Project Development at Ameresco.
Image: Tesla
Construction began in December 2024 and features 58 Tesla Megapack 2XL units installed at a Nucor substation within Mohave Electric Cooperative’s territory. The Ameresco-owned system operates under a 20-year Storage Services Agreement (SSA) and is managed by the Arizona Electric Power Cooperative. A complementary 25 MW solar asset is also scheduled to begin operation in 2026.
Tesla’s Megapack is its flagship utility-scale energy storage solution. Designed for grid and industrial applications, each Megapack can store massive amounts of energy and discharge it when needed, helping stabilize demand and integrate renewable sources like solar and wind into the grid. The technology has already become a cornerstone for large-scale energy storage projects across the U.S., Australia, and other global markets.
This milestone follows a series of major wins for Tesla Energy in 2025. Earlier this summer, Tesla secured a massive $2.7 billion order for Megapacks from Georgia Power, one of the largest single contracts in the company’s history. Last month, Tesla also unveiled the Megapack 3 — a next-generation design featuring 5 MWh of usable AC energy per unit and a streamlined architecture for faster installation, improved efficiency, and greater long-term reliability.
