Real-world experience from utilities with a relatively high penetration of light-duty EVs shows that EV charging brings additional utility revenues that vastly exceed the costs to generate and deliver the additional energy. This may be surprising given the concerns expressed in some industry opinion pieces on the ability of the grid to support EVs. However, in California, with high EV penetration and otherwise relatively low average residential load, only 0.15% of EVs required a service line or distribution system upgrade. At a system level, a Hydro-Quebec study shows that average home charging of an EV draws only 600 watts on peak – a small amount. It is worth noting that these two examples do not even rely on EV load management, which would further lower contribution to peak load.
In practice, many factors contribute to mitigating the impact of unmanaged EV charging on the grid. For instance, many owners of long-range EVs only charge at home once or twice a week, and not necessarily at peak system time. Also, many EV drivers are simply charging off a standard 120 V wall plug – slow but enough in most circumstances. More and more drivers charge at their workplace or at public stations, with diversified load curves. At the local level, distribution transformers used for residential customers are typically loaded at 25% to 30% of their rating; a few hours a year may be above the kVA rating of the transformer, but with little consequence.
If anything, the advent of EVs may get electric utilities growing again: current year-over-year electricity consumption growth (kWh) averages below 1% in North America but was about 2.5% as recently in the 1990s. Perhaps incredibly, yearly growth was about 8% to 10% in the 1950s and 1960s, as a wave of electrification propelled the economy. The ADN of electric utilities includes building the electricity grid and adding capacity.
Looking forward, various forecasts of the electricity use from EV adoption range from a fraction of a percent to perhaps 2% per year – not negligible, but clearly manageable in view of past growth rates.
Overall, grid impacts of light-duty EV load profile over at least the next decade should be relatively modest and net economic benefits from additional utility revenue vastly exceed costs. Those benefits will exert a downward pressure on rates for all utility customers – not just to those driving EVs. For example, Avista estimates that the net present value to ratepayers of a single EV on its system is $1,206 without managed charging. Furthermore, shifting charging to off-peak or high renewable generation periods further improves benefits – up to $1,603 per EV for Avista. Furthermore, EV drivers also gain from lower maintenance and operating costs. And besides, the switch to EVs significantly reduce greenhouse gas and other harmful air pollutant emissions.
This post was initially published at https://chargehub.com/en/blog/index.php/2020/03/25/ev-charging-puts-downward-pressure-on-rates/.
 Joint IOU Electric Vehicle Load Research – 7th Report, June 19, 2019.
 Public Fast Charging Service for Electric Vehicles, Hydro-Québec, R-4060-2018, HQD-1, document 1.
 Electric Power Distribution Handbook, T.A. Short, chapter 5. Some winter-peaking utilities are even planning the overloading of distribution transformer, counting on the low ambient temperature to cool it down.
 https://data.nrel.gov/files/90/EFS_71500_figure_data%20(1).xlsx, figure 2.1, for US data.
 For examples of forecast electricity use from EV adoption, see:
– Mai et al., Electrification Futures Study, page 82. https://www.nrel.gov/docs/fy18osti/71500.pdf.
– Canadian electric vehicle transition – the difference between evolution and revolution, EY Strategy, October 2019, page 9. https://assets.ey.com/content/dam/ey-sites/ey-com/en_ca/topics/oil-and-gas/canadian-electric-vehicle-transition-the-difference-between-revolution-or-evolution.pdf.
 Electric Vehicle Supply Equipment Pilot Final Report, Avista Corp., October 18, 2019.