Americans drive 3 trillion miles per year in their cars and burn 134 billion gallons of gasoline per year. Those 134 billion gallons cost 530 billion dollars at 3.95 per gallon ( 2012 average price ). Total electric production in the US per year is about 4.1 trillion kWh Total generating capacity is about 9.2 trillion kWh ( less than half is utilized ) If those 3 trillion miles were ( magically ) driven electrically, it would require about 1 trillion more kWh at 3 miles per kWh wall to wheel. That 1 trillion kWh would cost about 120 billion dollars assuming 12 cents per kWh and require us to use idle capacity in coal, oil or natural gas generation. The average cost of electricity in the US is 9.9 cents per kWh across residential, industrial and commercial customers, but assume a 20% increase because of additional fuel usage ( total guess ). If we drove the 3 trillion miles electrically we could save 410 billion dollars per year over gasoline. Now suppose we took that 410 billion dollars and used it to build solar PV. Solar PV installed by utilities runs close to $2 per watt ( spending $400+ billion dollars on it should surely drive the cost down but we'll stick with $2 ) So we could add 205 billion watts of solar PV per year with the gasoline savings. One watt of solar produces about 1600 watt hours per year in a quality location. So that would add 328 billion kWh to the production mix per year. So it would take a little over 3 years to add enough solar to make all the energy needed for the EVs from solar and stop using additional fossil fuels. ( note that at the end of those 3 years, the price of electricity for the EVs would go down significantly, but I wont bother calculating that ) It would take another 5 or so years to add enough solar to completely eliminate coal from the US energy mix. At that point the grid would be about 55% solar and the rest natural gas, nuclear, hydro and wind - then we could stop investing in solar and make driving nearly free and electricity prices would be dramatically lower than they are now. Of course this isn't a real plan. 100+ million EVs won't appear out of nowhere. EVs are still expensive and the operating cost savings over gasoline are needed to pay for the EVs themselves. 55% solar PV is not practical. Some portion of solar generation needs to be solar thermal which allows for collection during the day and continuous production over night. I don't know what the proper mix of solar PV, solar thermal, wind and natural gas is. This is just an exercise in exploring how much we spend on gasoline and what else we could do with that money.