Great to see someone actually doing some calculations instead of just presenting a cosy vision. For example, they argue that - contrary to what Elon Musk implies with his illustrations - the solar cells on the roof of the gigafactory will only be able to generate a small fraction of the energy required to run it.
> The average solar insolation in Arizona is 1,964 kWh/m2/yr (in Phoenix). If we assume a solar PV efficiency of 15%, one m2 of solar panels would generate at most 295 kWh per year. Consequently, almost 68 square kilometers of solar panels (6,800 ha) would be required to power the factory -- a calculation that also relies on the assumption that solar energy is equally distributed throughout the days and the seasons (or stored in batteries), and that there's no open space between the panels. Remarkably, Tesla shows an illustration of the factory with solar panels on the roof. Knowing that the factory will occupy a surface of 1 ha, while 6,800 ha of solar panels is required to run it on renewable energy, Tesla's claim is an obvious example of greenwashing -- and everyone seems to buy it.
> The average solar insolation in Arizona is 1,964 kWh/m2/yr (in Phoenix). If we assume a solar PV efficiency of 15%, one m2 of solar panels would generate at most 295 kWh per year. Consequently, almost 68 square kilometers of solar panels (6,800 ha) would be required to power the factory -- a calculation that also relies on the assumption that solar energy is equally distributed throughout the days and the seasons (or stored in batteries), and that there's no open space between the panels. Remarkably, Tesla shows an illustration of the factory with solar panels on the roof. Knowing that the factory will occupy a surface of 1 ha, while 6,800 ha of solar panels is required to run it on renewable energy, Tesla's claim is an obvious example of greenwashing -- and everyone seems to buy it.