All of the calculations are for energy, not power. In other words, you might produce 2400 MWh per day, but that doesn’t mean you’ll always have 100 MW available at any given instant. Sometimes you’ll generate more, other times less. Obviously there will be no solar production at night and less wind production on calm days. To be fully off-grid, Tesla will need some form of storage. As I surmised in a previous article, Tesla is probably shooting for more than the EV market; it seems logical for them to be looking into grid-level storage as well. What better way to showcase that than to include Li-ion batteries for on-site storage?

via Can Tesla Power Its Gigafactory with Renewables Alone? > ENGINEERING.com.