They will reach full capacity and factory completion by 2020. The first Gigafactory is getting maxed out with the production of about 500,000 Tesla cars and charging battery products in North America.
Elon Musk has talked about the need for ten to twenty Gigafactories for Tesla to makes planned products and volume. He also said the world would need one hundred Gigafactories to make electric cars and batteries for the world.
There are recent projections for 17 times more battery production by 2030. However, the battery forecasts keep increasing and the pace keeps accelerating.
The factory passed 20 Gigawatt-hours (GWh) of batteries per year in mid-2018. Panasonic will add 3 battery cell production lines. It will result in an annual production rate of 35 GWh. Tesla has increased the planned total capacity to 105 GWh of battery cells and 150 GWh of total battery pack output.