On September 8, 2025, in Las Vegas, Tesla unveiled two new grid-scale battery storage systems—Megapack 3 and Megablock—designed to accelerate deployment, increase energy density, and reduce project costs, as part of the company’s expansion in utility-scale energy storage systems, Reuters and industry sources report.
Product Details and Technical Specifications
The Megapack 3, the latest iteration of Tesla’s Megapack line, increases energy capacity to approximately 5 MWh per unit, up from about 3.9 MWh in Megapack 2XL, integrating Tesla’s silicon-carbide inverter, simplified fire protection, and a thermal bay with 78% fewer connections to enhance reliability.
System Configuration and Advantages
The Megablock is a pre-engineered, medium-voltage energy storage system that integrates four Megapack 3 units, a megavolt transformer, and switchgear into a plug-and-play platform. It delivers 20 MWh AC capacity, supports over 10,000 cycles, has a 25-year lifespan, and achieves 91% round-trip efficiency while operating in temperatures ranging from –40 °C to 60 °C.
Tesla projects a 23% faster installation, up to 40% lower construction costs, and a site-level energy density of 248 MWh per acre. The company claims that a Megablock configuration can be commissioned at 1 GWh in just 20 business days, potentially powering 400,000 homes in under a month.
Manufacturing and Supply Chain
Tesla intends to begin Megapack 3 production in Houston by late 2026, supported by cell supplies from its Houston Megafactory (50 GWh/year capacity), a Nevada LFP cell facility (around 7 GWh), and third-party partners.
Strategic Context
The announcement reflects Tesla’s strategy to expand beyond electric vehicles into broader utility infrastructure amid increasing demand for renewable integration and grid flexibility. It follows a $4.3 billion LFP battery supply agreement with LG Energy Solution, aimed at reducing dependence on Chinese imports and strengthening U.S.-based supply chains. Tesla also recently signed a $557 million deal to establish a Megapack-based energy storage station in Shanghai, underscoring its global deployment ambitions.
Summary
Tesla’s introduction of the Megapack 3 and the integrated Megablock represents a notable development in grid-scale battery storage. By boosting energy density, accelerating deployment, and lowering costs, these innovations position Tesla to strengthen its role in utility-scale energy storage amid growing demand for scalable clean-energy infrastructure.