That is mainly because the increase in storage capacity has come at the expense of a 64% increase in mass, 33,000 pounds (14.97 tons) and an increase in size in all its dimensions: it is 27% longer, 3% wider and 17% higher. In other words, the energy density is actually worse than other batteries used by Tesla, a fact that clearly suggests the use of lithium iron phosphate for this particular case.
As a general rule of thumb, in electric vehicles it is very important to keep the mass at bay in order to reduce the energy consumption of moving the battery pack itself – apart from moving all the rest of the components in a car, obviously -, and also for reasons of active safety, and many other considerations. But when it comes very specifically to static storage, those considerations applied to cars are not so important, as Elon Musk explained in 2021: "However, for static storage, the energy density is not that important because it stays in the ground".
Indeed, the purpose of the Megapacks is to store a lot of energy, and so whether they are bigger or heavier actually becomes a secondary consideration: they already need a lot of space, and the increase in size is very small in comparison anyway; and as long as the architectural team is minimally competent, the weight gained is also bearable on the right terrain with the right foundations.
On the other hand, iron and lithium-based chemicals do not need cobalt, a somehow controversial material which mainly cones from sources in the Congo in Central Africa, where it is actually difficult to guarantee that the supply does not disturb Western minds that think about human rights, labor and environmental issues. On the other hand, there is plenty of iron on this planet, almost everywhere, and which by the way is fairly simple to obtain.
You can order the new Tesla Megapack for 2.4 million dollars on the Tesla website in the US, with 1.9 MW of power and 2 hours of autonomy, and if you need to have 4 hours of autonomy the price actually drops to $1,93 million, although the power is lower: 1 MW.
All images courtesy of Tesla Inc.
Nico Caballero is the VP of Finance of Cogency Power, specializing in solar energy. He also holds a Diploma in Electric Cars from Delft University of Technology in the Netherlands, and enjoys doing research about Tesla and EV batteries. He can be reached at @NicoTorqueNews on Twitter. Nico covers Tesla and electric vehicle latest happenings at Torque News.