The average American drives about 55 miles per day. A typical EV uses about 300Wh per mile. That gives us a typical demand of about 17kWh of charging per day. A standard single-phase fast charger puts out 7kW and a three-phase fast charger puts out 22kW. There's plenty of opportunity to spread out that demand throughout the overnight off-peak period, because most EV users only need to charge for a couple of hours per day.

With smart metering, EVs can also feed energy back to the grid during transient demand peaks. Users won't notice if 5% of their battery is ringfenced for grid storage, but it'll provide a vast proportion of the storage capacity we need to manage an all-renewable grid.

Between the rebalancing of peak and off-peak demand and the potential to use EVs for grid storage, the widespread adoption of EVs is likely to be of net benefit to the electricity grid.

What if something unusual happens? Imagine there is a long blackout during those 9pm to 6am hours. It doesn't have to be the entire city, just a significant number of homes. The next morning, thousands of drivers find they don't have enough power to get to work. Thousands of cars are suddenly charging beyond the expected 9pm to 6am window. Will the grid be able to handle full daytime load in addition to this huge unexpected load? How much would it cost to upgrade the grid to worst case scenario? (entire city blackout during 9pm to 6am)?

If charging shifts to early-mid morning after an overnight outage, I would expect that there's enough distribution/generation capacity to handle it. Take a look at this curve again:

http://www.caiso.com/Pages/TodaysOutlook.aspx#SupplyandDeman...

Although demand at 7:00 AM is 5 gigawatts above the 4:00 AM nadir, it's still 15 gigawatts below the 5:00 PM peak. Since electrical generating and distribution systems are sized to handle those early-evening peaks, shifting charging some hours away from the traditional peaks (either direction, later or earlier) should allow vehicles to recharge daily without increasing daily peak demand.

What about places that aren't California? Even places that have more seasonal electricity demand in the winter than in the summer, like the UK, see their daily peaks in the early evening. Peak demand hours are more about human behavior than geography. People come home after work, cook dinner, turn on lights, do chores... Traditional peak demand hours coincide with this burst of domestic activity. Scheduling charging away from the traditional peak electricity times makes more efficient use of existing infrastructure and allows peak distribution/generation capacity upgrades to be delayed and minimized even with rising adoption of home-charged EVs.

Which also reminds me of 120V 15A/20A charging, which the vast majority of EVs will likely use.

It may require that electric providers require deferred charging, even to the point they set when you can. While you could defer your charging don't expect that everyone will. As we see with charging stations in areas with more EVs there are those who just don't care. We need to instruct future owners the expected etiquette

Dynamic pricing could work better than etiquette

In the UK, differential tariffs were introduced in the 1970s for the benefit of homeowners with electric storage heating. On the Economy 7 tariff you get substantially discounted power for a seven hour period overnight, often as much as 50% lower than the peak rate. Pretty much every British EV owner uses this tariff and a timed charger, because it offers huge cost savings.

https://en.wikipedia.org/wiki/Economy_7

peaks will happen if enough people do it at the same time. Almost every summer (maybe except this one), there's always that heat wave that taxes the grid. A solvable problem for sure (just like how we can now handle cell phone overload during emergencies) but lets not pretend the problem doesn't exist.

philipkglass showed how the problem is solved, he did not ignore the problem.

philipkglass showed how the problem is solved

jasonmaydie showed that even if a problem is solved it can still be a "problem"