Finding
Megablock makes Tesla a grid-hardware OEM: batteries, inverters, transformer, switchgear and controls ship as one tested skid
Announced in September 2025 for delivery from late 2026, Megablock combines four Megapack 3 units (5 MWh each, 20 MWh total) with a medium-voltage transformer and switchgear. Tesla claims up to 40% lower construction cost, 23% faster installation and up to 1 GWh deployable in 20 business days. Megapack 3 and Megablock are built at Tesla's Brookshire, Texas Megafactory near Houston.
Bundling the transformer and switchgear removes the two items a storage developer usually buys separately and waits longest for - large transformers take about 128 weeks. Electrical and control interfaces are standardized, so arrays grow by adding blocks; Tesla's software discovers and configures new blocks, and Autobidder and Opticaster trade and schedule them.
Competition is at the integration level. BYD passed Tesla as the largest storage integrator in 2025 (13% against 10%, Benchmark) with MC Cube and the 14.5 MWh HaoHan; Sungrow's PowerTitan 3.0, CATL's TENER Stack and Fluence's Smartstack all push toward larger, more complete blocks. Megablock is Tesla's answer: own everything from cell to medium-voltage terminals.
Contents
What is on the skid
| Component | Megablock | Conventional BESS site |
|---|---|---|
| Batteries | Four Megapack 3 units, 5 MWh each | Containers from one vendor, PCS from another |
| Inverters | Tesla-designed, integrated with pack firmware | Separate PCS skids |
| MV transformer | On the skid, supplied by Tesla | Procured separately; long lead |
| MV switchgear and protection | On the skid | Field-installed, site-specific |
| Thermal | Heat-pump based, shared by packs and electronics | Per-container HVAC |
| Controls and EMS | Tesla site controller; Autobidder, Opticaster | Third-party EMS integration |
| Commissioning | Software discovery and configuration | Manual, multi-vendor testing |
Comparison
Field-built substation and BESS against Megablock
| Factor | Field-built substation + BESS | Megablock |
|---|---|---|
| Vendors | Transformer, switchgear, BESS and controls from different suppliers | One |
| Transformer supply | Long lead times can delay projects one to two years | Bundled with the block |
| Engineering | Site-specific design for each project | Standard block interfaces |
| Civil work | Bespoke foundations and trenching | Repeatable pads and routing |
| Testing | In the field | In the factory, before shipping |
AI data centers
Why AI data centers need oversized storage
GPU clusters ramp from near idle to full power in tens of milliseconds, and thousands of GPUs step together. xAI's Colossus in Memphis uses Megapacks to buffer those swings.
| Requirement | Reason | Sizing |
|---|---|---|
| Fast inverter response | Synchronized training steps create load ramps and collapses in milliseconds | Inverter power ~1.2-1.5x peak IT load |
| Storage energy | Ride through grid events for minutes; shift energy | ~1.5-2.0x peak IT load, in MWh |
| Power quality | Harmonics and tight voltage and frequency tolerances | Grid-forming control |
| Grid-friendly profile | Utilities want a flat load even when compute swings | EMS shapes the site load |
Sources
Sources and scope
- Scope
- Tesla Megablock
- Sources
- Tesla (September 2025 announcement; 2025 deployment report); Benchmark Mineral Intelligence; ElectronsX sizing assumptions
- Updated
- October 2026