What did Tesla unveil at the Las Megas event?

Tesla unveiled the Megapack 3, a next-generation utility-scale battery, and the Megablock, a pre-engineered system integrating multiple Megapacks with transformers and switchgear.

What is the capacity of the Tesla Megapack 3?

The Tesla Megapack 3 offers up to 5 MWh of usable AC energy per unit, a 28% increase over the previous Megapack 2XL.

How does the Tesla Megablock improve deployment?

The Tesla Megablock streamlines installation by integrating four Megapack 3 units with transformer and switchgear, enabling 23% faster deployment and up to 40% lower construction costs.

When will Tesla start producing the Megapack 3?

Tesla plans to begin producing the Megapack 3 at its Houston Megafactory in late 2026, supported by a 7 GWh LFP cell facility in Nevada.

Las Megas: Tesla Just Rewired the Future of Energy

Rebellionaire Staff
Sep 9
4 min read

Tesla Megablock

Las Vegas has seen its share of flashy shows, but last night Tesla Energy rolled out something different. Forget neon lights and slot machines—this was about raw power. Utility-scale power. The kind that keeps cities running when the sun sets or when the grid groans under peak demand.

The event was cheekily branded “Las Megas”, and the stars of the show weren’t cars or robots, but two massive additions to Tesla’s energy arsenal: the Megapack 3 and the Megablock. Both are built to shake up how fast we can deploy renewable energy at scale and how cheaply we can do it.

Megapack 3: Tesla’s Grid Battery Grows Up

Tesla didn’t reinvent the Megapack from scratch—they made it meaner, leaner, and way more adaptable. The new Megapack 3 takes everything the Megapack 2XL did and cranks it up.

Capacity upgrade: One unit now stores up to 5 MWh of usable AC energy—a 28% jump over the 3.9 MWh in the previous generation [4].
Cell innovation: Inside are 2.8-liter LFP cells, co-developed by Tesla. About 75% of the unit’s weight is just batteries, with a single module weighing as much as a Cybertruck [5].
Simplified guts: Tesla cut wiring complexity by 78% fewer connections, reducing potential failure points and making servicing easier [3].
Heat pump assist: Borrowing from its Model Y playbook, Tesla added a heat pump for thermal management, plus front-access servicing so techs don’t need to cut roof holes just to get inside [5].
Tough as nails: This beast runs anywhere from –40 °C to +60 °C, ready for Arctic winters or desert heat [5].

And the build scale? Tesla plans to produce these at a new Houston Megafactory starting in late 2026, targeting 50 GWh a year in output [5]. Feeding that will be a 7 GWh LFP cell plant in Nevada opening in 2025, plus partnerships with third-party suppliers [5].

That’s not a little side hustle. That’s global energy infrastructure in the making.

Megablock: Plug-and-Play Powerplants

If the Megapack 3 is Tesla’s refined grid battery, the Megablock is its hammer.

This isn’t just four Megapacks stacked together—it’s pre-engineered with its own transformer, switchgear, and automation built in. Show up with one of these blocks, drop it on site, hook it into the grid, and go [3][4].

Massive power in one block: Each Megablock delivers 20 MWh of AC energy, with a lifespan of 25 years and over 10,000 cycles [2].
High efficiency: Tesla claims 91% round-trip efficiency, even after auxiliary loads [2].
Fast installs, cheaper builds: Deployment is 23% faster and construction costs drop by up to 40% thanks to a new flexible busbar system that eliminates above-ground cabling [4].
Insane density: At 248 MWh per acre, these things can pack more energy into tight spaces—huge for utilities squeezed for land [2].
Speed at scale: Tesla says it can commission 1 GWh of storage in just 20 business days. That’s enough juice to keep 400,000 homes powered for a month [2].

Oh, and Elon dropped a side note: Tesla is going to start building its own transformers. In true Musk fashion, the message was clear—if supply chains get in the way, Tesla just eats them [4].

Why This Event Mattered More Than You Think

Let’s zoom out. Everyone loves talking about Tesla’s cars, FSD, or Optimus robots. But here’s the truth: the real trillion-dollar story is energy.

Tesla Energy is already flexing:

In Q2 2025, Tesla deployed 9.6 GWh of storage, bringing the first half of the year to 20 GWh—a 48% jump year-over-year [6].
Margins in the Energy division are running above 30%, accounting for nearly a quarter of Tesla’s total profits despite contributing just 12% of revenue [6].
Globally, Tesla still leads the pack with the #1 market share in battery energy storage systems, commanding nearly 40% in North America [6].

That’s the kind of growth Wall Street sleeps on until it doesn’t.

And now? With Megapack 3 and Megablock, Tesla isn’t just shipping batteries. It’s shipping instant grid solutions. Utilities no longer have to string together dozens of containers, transformers, and cabling from a dozen vendors. Tesla sells you the whole package. Drop it, wire it, flip the switch.

The Rebellionaire Take

The Las Megas event showed Tesla’s playbook:

Simplify the product until even massive utilities can deploy at speed.
Dominate margins by cutting costs and controlling more of the supply chain.
Scale manufacturing like it’s cranking out cars, but this time it’s megawatt-hours.

Think about that 1 GWh in 20 business days claim. Utilities used to plan these projects in years. Now we’re talking weeks. That’s not incremental. That’s a paradigm shift.

Wall Street can keep arguing about whether FSD is Level 4 or Level 5. Meanwhile, Tesla is quietly building the backbone of the renewable energy future. The lights in your house? The hospital down the road? The data center powering AI models? Increasingly, all of it runs on Megapacks.

So yeah, cars are fun. Robotaxis will grab headlines. But energy? Energy is where Tesla becomes unstoppable.

Sources

“Tesla Energy Announces New Mega Product as China EV Sales Still Lag.” Investor’s Business Daily, 8 Sept. 2025, www.investors.com/news/tesla-energy-megablock-china-ev-sales-tesla-stock/.
“Tesla Stock Climbs Premarket on Megapack 3, Megablock Launch; Musk Promises Cheaper, Quicker Energy Storage.” Stocktwits News, 9 Sept. 2025, stocktwits.com/news-articles/markets/equity/tesla-stock-climbs-premarket-on-megapack-3-megablock-launch-musk-promises-cheaper-quicker-energy-storage/chw0yN9Rdsm.
“Tesla Unveils Megapack 3 and Megablock Giant Grid Batteries for Cities.” TeslaNorth, 9 Sept. 2025, teslanorth.com/2025/09/09/tesla-unveils-megapack-3-and-megablock-giant-grid-batteries-for-cities/.
“Tesla Unveils New Generation of Utility-Scale Batteries.” PV Magazine, 9 Sept. 2025, www.pv-magazine.com/2025/09/09/tesla-unveils-new-generation-of-utility-scale-batteries/.
Alvarez, Simon. “Tesla’s New Megablock Powers 400,000 Homes in Under a Month.” Teslarati, 9 Sept. 2025, www.teslarati.com/tesla-new-megablock-powers-400000-homes-in-under-a-month/.
“Tesla Energy Has Quietly Become the Company’s Most Profitable Division.” PV Magazine USA, 4 Aug. 2025, pv-magazine-usa.com/2025/08/04/tesla-energy-has-quietly-become-the-companys-most-profitable-division/.