Tesla Megapack 3 Enters Mass Production: Cabinet Capacity Up 28%, New Texas Factory Begins Operations

Tesla has officially launched mass production of its next-generation grid-scale energy storage system, the Megapack 3. The first units have rolled off the assembly line at the company's new Megafactory in Brooks County, Texas, USA. Built from groundbreaking to commissioning in just 16 months, the facility is designed for an annual output of 50 GWh — exclusively for Megapack 3.

This milestone marks the transition of the Megapack 3 and Megablock technologies — announced last September — into commercial delivery. While Tesla revealed detailed specifications at launch, mass production had not yet commenced. Today's launch represents a critical execution step in Tesla's ongoing iteration of large-scale energy storage systems.

Each Megapack 3 cabinet delivers a nominal capacity of approximately 5 MWh — up ~28% versus the previous-generation Megapack 2 XL (3.9 MWh) — while retaining identical physical dimensions. Tesla achieved this energy density leap primarily by adopting larger-format cells (2.8 liters) and simultaneously optimizing its thermal management system: connection points are reduced by 78% compared to the prior generation, significantly lowering risks of coolant leakage and failure in liquid-cooled systems — and shortening installation and maintenance time.

A more fundamental upgrade lies in the Megablock architecture: it integrates up to four Megapack 3 units (totaling ~20 MWh), medium-voltage transformers, and switchgear into a single factory-assembled unit. Compared to traditional on-site integration — which requires extensive medium-voltage cabling — the Megablock drastically compresses project timelines. Tesla claims deployment density of up to 248 MWh per acre, with 1 GWh projects installable within 20 working days — a roughly 23% improvement in overall construction efficiency.

This addresses a key bottleneck in today's large-scale energy storage deployments: lengthy grid interconnection approvals, complex on-site electrical work, and extended commissioning cycles — all driving up cost and schedule risk. Pre-integrating complex systems at the factory is emerging as the core enabler for faster, scalable rollout. Tesla recently signed a $5 billion, 25 GWh Megapack order with European utility NatPower; data center operators are also accelerating procurement of energy storage systems.

The rapid commissioning of the Brooks County factory also reflects Tesla's strategic response to mounting production pressure and intensifying competition. As CATL, Fluence, and BYD accelerate their energy storage initiatives, Tesla urgently needs expanded capacity. With its dedicated 50 GWh output, this facility is poised to surpass the total production of Tesla's Lathrop, California plant — and become its largest global energy storage manufacturing base. However, actual ramp-up pace remains constrained by supply stability of large-format lithium iron phosphate (LFP) cells, as well as U.S. import tariffs on LFP batteries, which are pressuring Tesla's energy business gross margin.