Every time I post an article on Seeking Alpha about the growth of electric vehicles, I get a bunch of posts from naysayers that it will require major upgrades to the grid. However, none of that is likely true. There probably needs to be little to no change in infrastructure and here’s a look at why.

The Duck Curve

To understand our electricity consumption, look at this chart modified from GreenTechMedia depicting the “duck curve” of electricity consumption in California. I’ve taken the chart and placed it right next to a copy of the chart showing a two day span:

duck curve peaks

“Net Load” in this case is the total load minus intermittent sources like solar and wind. Notice how, regardless of the time of the year, the mid-day and night time loads are lower than AM and early PM loads.


Adding EVs To The Equation

Currently less than 2% of vehicles in California are electric. Let’s say suddenly 10% of the cars on California roads become electric. This will take many years but let’s just assume it happens overnight. As an EV driver, I generally charge my EV at night. Before we got solar panels, we were on a time of use (TOU) plan and charged our EVs when power was the cheapest. My thinking is that either people will charge EVs at night or they will charge EVs at work, neither of which represents peak hours. So effectively electric cars are likely to smooth out the duck curve. Let’s just see how much:

Let’s stick with California and use the chart above. There are roughly 15 million vehicles in California. I’ll assume that most vehicles are charged daily and drive an average of 35 miles/day (~12,000 miles per year). Electric vehicles go about 3.5miles/kWh so each car will use about 10kWh / day. Multiply that by 1.5 million and you get 15 million kWh. Let’s look at what this would look like with charging at night. For each period of the year, I’ve rough approximated two different lines – one is of people starting charging near the peak (plug in when you get home) and the other is if people charge mostly when power is cheaper:

In power production, the bigger problem is the slope of a curve not the width of the peak. A lot of EVs charging at night probably is unlikely to affect the slope going up but it will definitely help reduce the slope at night on the way down. If more people choose to charge at cheaper power rates, the night time slope will get much gentler. If some people charge during the day, the day time slope will get a shallower. The conclusion to draw is that unless everybody decides to charge their electric cars during peak hours, the growth of electric cars is likely to be a non-issue for the grid and it might also be beneficial to the grid as more renewables make the duck curve worse. This is not even taking into account upcoming technologies like storage, virtual grids, v2g etc., which I’ll leave for future posts along with a more detailed look.

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