Tesla Energy showcased its latest BESS, featuring up to 5 MWh of storage capacity, at RE+ 2025
The company also unveiled its compact and modular design platform that combines multiple BESSs, a transformer, and switchgear in a pre-engineered structure
It will start commercial production of these displayed products in its USA factory by late 2026
Tesla Energy, the energy generation and storage segment of leading BEV manufacturer Tesla Inc., introduced 2 major additions to its energy storage portfolio, Megapack 3 and Megablock, both designed for the US’s utility-scale storage projects, at RE+ 2025.
Megapack 3 is the company’s latest utility-scale battery energy storage system (BESS), which it says delivers a significant improvement in performance compared to its predecessor, Megapack 2XL. Its lithium-iron-phosphate (LFP) battery cells are sourced from the US, Southeast Asia, and China. Equipped with silicon carbide (SiC) based power electronic switching devices, each BESS offers up to 5 MWh of storage capacity compared to its predecessor’s 3.9 MWh. Additionally, it has incorporated a heat pump with scaled-up capacity from Model Y, the company’s popular BEV. Featuring an operational temperature range of -40°C to +60°C without derating, the product is capable of operating in the US’s extreme environmental conditions. Weighing 39,000 kg, it can be transported in a standard 7-axle trailer and installed without any on-site assembly. The company plans to start commercial production of this product at its upcoming factory in Houston, which is expected to have an annual output capacity of 50 GWh, in late 2026.
The other exhibit was the company’s BESS solution, Megablock. It consists of 4 units of the Megapack 3 paired with a transformer and a switchgear in a pre-engineered modular structure, creating a block with a storage capacity of up to 20 MWh. It offers a consistent round-trip efficiency (RTE) of up to 91%, including auxiliary loads, at medium voltage level. It is rated for more than 10,000 cycles of charge or discharge across its lifespan of up to 25 years.
Megablock features a busbar assembly, which eliminates above-ground cabling between Megapacks and the transformer, enabling a ‘plug and play’ architecture that simplifies on-site installations. The company says that given the ability to scale up to 1 GWh of capacity by paralleling 50 Megablocks within 20 working days, deployments can be quicker compared to its predecessors. The company adds that with this solution, the site-level energy density can reach up to 248 MWh AC per acre.
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