These are the kind of calculations that make me weep - somebody getting happy with numbers without engaging their brain as to the answer. Obviously the Tesla factory is not going to require 20,000,000 Megawatthours to operate - that is as much as the whole electricity production of the State of New Hampshire.
Assuming their input data is actually correct, I will speculate they are calculating the energy cost of the entire lithium battery production from raw materials, such as extracting lithium from mineral deposits, the majority of which would happen before the materials arrived at the Tesla factory.
I also expect Elon Musk knows what his electricity bill is. Given his investment in green technologies and his general success in delivering projects, I would be rather surprised if he advertised a solar factory if there was a chance he would be out by 4 orders of magnitude on how much power he would need.
Assuming their input data is actually correct, I will speculate they are calculating the energy cost of the entire lithium battery production from raw materials, such as extracting lithium from mineral deposits, the majority of which would happen before the materials arrived at the Tesla factory.
I also expect Elon Musk knows what his electricity bill is. Given his investment in green technologies and his general success in delivering projects, I would be rather surprised if he advertised a solar factory if there was a chance he would be out by 4 orders of magnitude on how much power he would need.