If there were 10 million EVs in California then they would need 28 TWh/year. The US has added up to 100 Terawatt hours per year over ordinary recent four year periods. Adding power 25-30 TWH/yr would enable 10 million EVs per year to be added by the USA.

California generates about 280 TWh/year.

10% of the energy can be time-shifted with battery storage and with evening charging from the grid. This initially does not require new net energy generation because of the charging during non-peak times. This is what is happening now.

The US could handle 50 million EVs with offpeak charging with addition of some battery storage equal to one-fifth of the batteries used in the EVs themselves.

Getting back to average energy generation additions for five-year periods prior to this last decade would easily accommodate

Converting to 100 million electric cars for the entire united states can be done with off-peak charging and adding new net energy generation at the historical rate.

If someone installs solar power in California then a 370 watt panel would produce 2.2-kilowatt hours per day. 2000 watts of rooftop solar would produce 11-kilowatt hours of energy per day in California which would offset the energy used by an electric car driving 12000 miles. This would cost about $4000-5000 after tax credits. It would cost about $8000 after tax credits to add one 13.5 kwh Powerwall.

The additional solar and battery costs would be about the level of the cost of gasoline and oil changes for the first three to five years of car ownership.

The sunnier middle to bottom half of states would not have an issue affordably adding solar and batteries. If your electric car was $40k-60k then adding $12k-20k for the solar and batteries would enable charging of the car. Those batteries and solar can be added to homes or to public charging infrastructure.