Let's use some round numbers. A typical home use about 36 kWh per day while a car needs about 12 kWh per day. So in terms of average power, that's 1.5 kW for a home and 0.5 kW. But really it is kind of silly to talk about average power because demand varies through out the day and utility capacity is determined by peak demand not average demand. So if everyone had a home and a car which demand would determine the peak. Home use of power is very hard to shift--try running the AC at night and not at mid day. By contrast, car charging can happen at any time at discretion. Thus, people will mostly charge their cars when rates are low or to save on demand charges when household demand is low. So any economical charging of cars will atlctually reduce peak to average power ratios, not make them worse as the Toyota executive is suggesting. Surely the top engineer at Toyota understands this, so he must be engaging false and misleading claims.
The impact of battery storage on the grid whether stationary or automotive will smooth out power demand, not make it worse. Toyota should be ashamed of itself for suggesting otherwise.
Just to add some additional measure to the ratio of supercharging vs. home charging, in one of the shareholder's letters (don't remember exactly which quarter, but it was during the last year) TM included total quantity of miles that was traveled using energy from superchargers. There was also contemporaneous information on total miles driven by the fleet of MS on the roads. So back then I calculated the ratio of miles traveled on supercharged energy vs. total energy used by the fleet - it was around 8%.
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