What
@Lloyd was talking about is true. The utilities need to manage the peak electricity usage to avoid blackouts. If your car starts charging, utilities will burn more natural gas to cope up with the demand. Consumption of electricity and generation of it must match every second, or the frequency of AC will fluctuate, or worse, cause voltage drops/rises.
Tesla chose the original design to "half" the demand charge by limiting to 135kW per two stalls. Supercharger V3 now requires 250kW per ONE stall, making demand charges roughly FOUR TIMES more expensive to them at peak.
InJapan demand charges are timed per minute, and lasts one year. That means if you use peak power for 1 min, then the next one year you have that rate (per kW base charge). Here in Tokyo demand charge for 1kW is approx 14.34 USD. With one 250kW supercharger stall, Tesla will pay 3585 USD per month per stall, in addition to "per kWh" electricity cost.