Serniter, yes, you are right. Sorry, I did not explain well.
I made calculation from the fact NA households have higher current rating than those in Japan. The 14/7-hour rating is based on 15 amps of max current. I think we can supply twice as much during off-peak hours (as long as we are not using AC, kitchen stove, oven and clothes dryer at the same time). The battery pack itself can take much higher current. The quick charging system is rated at 50kW, which is about 170 amps at 300 volts DC.