Stating the obvious, there is a factor of 3 difference in size between a 100 MWhr battery and a 300 MWhr battery. It was reinforced by the fact that Tesla had recently installed a 20 MW, 80 MWhr battery in Southern California. On Twitter, Musk had made an attractive, but guardedly qualified price estimate of $250/kw-hr for installations larger than 100 MWhr. Premier Jay Weatherill has a total of A$550 million available, and Tesla's massive battery is only a part of the necessary capability. The South Australian government and Tesla have declined requests to provide details about the total project cost for the "world's largest grid-connected battery."

Source: Forbes July 07, 2017 12:20 UTC