Tesla reported in December they have the ability to produce...

Tesla reported in December they have the ability to produce 10,000 battery Megapacks per year used in electricity grid storage. The updated Megapack design contains 3MWh of Lithium Iron Phosphate batteries (LFP). Although heavier than the NCM811 batteries used in their cars the LFP batteries are safer without the worry of thermal runaway and weight is not an issue.
To equate this into layman's terms 1MWh = 1,000KWh.
A model S has a 100KWh battery pack so a 3MWh Megapack has about 30 Model S batteries in terms of quantity.
So 30 x 10,000 Megapacks per annum is equivalent to approx 300,000 Model S packs annually.

So this 400MWh project is equivalent to about 4,000 Tesla Model S's worth of batteries

Here is an open Megapack.

Here is the previous SA Big Battery.