Usually automated storage and retrieval is a sign of misplaced priorities in manufacturing, as storage and retrieval add capital and operating costs (and more importantly cycle time to the inventory, and lags in cause and effect as downstream processes are often the place where flaws are found- they tie up money and effort and delay the discovery of flaws creating a junk exposure/risk) with no actual value added to the product.
So in trying to sort this, if an IC guy designed this thinking that buffers are good, there are differences between data and physical product, but Tesla is pretty smart, and they know that inventory turns matter, so this would be bad sorting on my part.
If color changeovers are so expensive that this facility is the only way to get more than one color on a truck, that might make sense.
I am from the school of low rate parallel machines that don't need a buffer in case they break down. Shigeo Shingo school I guess.
If it is to store finished product to avoid crossing the threshold, because the natural area of distribution is large, it is a natural capacitor, I would tend to rent space in mall garages, on a temporary basis. Or even rail cars or trucks.
If there is some sort of soak time required in the manufacturing process - reforming or something like that, it could make sense. Maybe they are moving a battery process step to occur in vehicle?
I see a pile of money, delay and misdirected effort in these types of buildings. Sometimes to serve a fragile high rate process with slow changeover time. If the inventory money and effort and lag costs were directed toward buying more manufacturing equipment or improving changeover speeds, ... usually it is better not to have these sorts of buildings.
Pretty sure I am missing something.
[Edit: AWK mind bending stream processing with no memory management and Shigeo Shingo single minute exchange of die( and other stuff) are the two things that set my expectation of high speed and low cost to a point where others think "impossible unrealistic." Appreciating these things creates conflict with those who don't...]
I wonder if the fact that Tesla is rather highly vertically integrated, whereas the plant when it was originally designed for NUMMI may have been laid out for more of a just-in-time manufacturing process plays in to this.
It seems to me that your "parts storage" for a JIT facility is the pipeline from your suppliers (their warehouses, ships, rail lines, trucks, etc...) to you.
For a vertically integrated environment, you are your own supplier for many of your parts, and thus you need some buffer space to accommodate those parts.