The answer is pretty simple; global production of battery cells suitable for automotive use is far, far below what is required for Tesla's goal of turning (forcing) the majority of the world's produced cars electric. Buying this capacity from a third party cannot be done; there is no seller capable of providing the product.
Global car production is on the order of 50 million vehicles per year, which means a required capacity of 2500GWh/year assuming 50GWh/car. 2013 li-ion battery production was 35GWh, some 1.5% of this number.
Tesla wants to reach a production rate of 500k cars/year in the next couple of years, and you probably wouldn't find a 3rd party manufacturer willing to eat the risk of upping the world's battery capacity by 50% to fulfil this contract. Never mind Tesla's long-term production goals, which are in the millions of vehicles per year.
Hence they're forced to do it themselves, same situation as the charger network on a bigger scale (which could in an ideal world be done by governments or a third party, but never on the short time scale required). I can't speak to the location of the factory.
Global car production is on the order of 50 million vehicles per year, which means a required capacity of 2500GWh/year assuming 50GWh/car. 2013 li-ion battery production was 35GWh, some 1.5% of this number.
Tesla wants to reach a production rate of 500k cars/year in the next couple of years, and you probably wouldn't find a 3rd party manufacturer willing to eat the risk of upping the world's battery capacity by 50% to fulfil this contract. Never mind Tesla's long-term production goals, which are in the millions of vehicles per year.
Hence they're forced to do it themselves, same situation as the charger network on a bigger scale (which could in an ideal world be done by governments or a third party, but never on the short time scale required). I can't speak to the location of the factory.