Electric Vehicles: Home Charging

Electric Vehicles: Home Charging
AP Photo/St. Paul Pioneer Press, Scott Takushi
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In my previous RealClearEnergy article on electric vehicle (EV) charging, I found that relying primarily on public fast chargers was not a realistic option. Based on the 80 miles I drive daily, between home and work, it would require over 200 hours per year to charge the Hyundai Kona EV as compared to less than five hours fueling my gasoline-powered car. This is also assuming a charger was both conveniently located and ready for immediate use. Clearly, home charging is a much better option.

I have had a home EV charger for several years and found charging my car was not only more convenient than having to fuel my (ICE) internal combustion-powered car but that home electricity is also less expensive than gasoline. But the questions remain: what are the impacts on my home energy bill and power consumption? What are the implications for grid capacity to supply power to charge the ever expanding number of EVs?

Several years ago I installed a Siemens VersiCharge Level II charger in my garage. It charged well but I could never get it to connect with my home WiFi which would allow me to program the charging time or find out how much energy I was using. I called the Siemens’ technical support line several times, but they were either unavailable or promised to call back and never did. Next time I will be more careful to check consumer reviews, since I found I was not the only one who purchased this charger and experienced these same problems. 

When it was time to purchase a different charger I opted for the Juice Box 32 by Enel X. The Juice Box was easy to install and connect with my WiFi. The app provides lots of information, and it is easy to track power consumption and program charging times. It is said that EV owners will prefer to charge their cars during non-peak power periods, such as between midnight and 5AM when power is plentiful. I found that my electricity provider, Dominion Energy, had an off-peak power plan. The cost of electricity is significantly higher during periods of peak-power demand and somewhat lower for off-peak periods. It is a voluntary program and available to the first 10,000 customers who also have a smart meter. I was surprised that even though this program has been available for over a year, I was still able to join the plan.

With all the many thousands of EVs in the DC area, the peak power plan is not very popular. Taking advantage of the program, I scheduled my EVs charging time to begin at 8PM, which is the end of the evening peak-power demand period. I have no idea if the peak power plan is going to save money. On its website, Dominion Energy says that it will soon include a calculator so power users can more easily determine if this is a good plan for customers. Another good feature of the Dominion Energy website is that it provides customers a detailed report of their power consumption broken down into half-hour units. This will allow me to see how much additional energy I consume when I charge my EV. 

I generally have been driving my EV back and forth to work weekdays and not usually on weekends when I use my (ICE) Nissan Titan truck. This is sometimes true on weekdays so I can easily compare the difference in my home power consumption between days when I charge my EV and those days when I do not. My home is heated by gas so my electrical consumption surprisingly has little deviation between night and daytime hours. Power consumption is highest in summer from air conditioning use.

The big question is when EV owners will choose to plug in their vehicles since this will have potential implications for grid capacity. Generally speaking, peak power demand is in the morning when people are waking and getting ready for the day and in the evening from 5PM to 9PM. According to the Dominion Power website, evening peak demand is at 8PM and then declines through the night. This is also true in California according to ISO, the California Independent System Operator. The narrowest gap between peak power demand and total energy availability is at the same time when people are coming home from work, cooking dinner, engaging in evening activities, and for some of us, plugging in our EVs. I realize that energy planners hope that EV owners will charge their vehicles after midnight when energy availability is plentiful, but will this actually happen?

Human nature says that absent compelling reasons to do so, people such as myself, will plug in as soon as they come home in order to assure that charging has begun. There are many reasons for this such as having a charged car ready for an emergency, or avoiding potential late night power interruptions. We have all experienced power outages late while asleep. Waking up late and seeing your clock radio light flashing on and off, the tell-tale sign of a power outage. Nothing like starting your day and discovering your EV is not charged as you expected. This happened to me one day. I was in a panic since I had difficulty finding the keys to my gasoline-powered car.

There are also studies about using EV batteries to help stabilize the grid by providing an additional power source during periods of peak power demand. As demonstrated in California and Germany, when there is a high dependence on renewable wind and solar energy, there are periods when additional power is needed to supply the grid. Some of the back-up could come from industrial sized batteries such as those being manufactured by Tesla and installed in such places as Australia, California, and now Texas. It is hard to understand how many EV owners would agree to such a plan, since it means coming home, plugging in, expecting charging to begin, but instead, due to high power demand and low renewable energy availability, electricity is instead drained from the battery. There is also the question of battery degradation since lithium batteries lose a small portion of their energy storage capacity each time they are discharged and recharged.

I was surprised how much my home electricity consumption increased during the hours when my EV charges. The Hyundai Kona EV surged power consumption by 369% and with my newest EV, the VW ID.4, due to its larger battery and more rapid rate of charge, consumption increased an astonishing 479%. Electricity demand would increase still further if my wife or someone else in my household also charged their EV at the same time. If all my neighbors owned EVs and charged them at home, would the existing power supply on the street be sufficient to charge them? Electricity consumption in the U.S. is expected to grow significantly as EVs sales inevitably increase. Because of its high adoption of EVs, Norway has the second highest per-capita electricity consumption in the world, according to the World Bank, and Bloomberg reports that is expected to grow 30% by 2040. 

One of the benefits of driving an EVs is that they are considered zero-emission. While EVs do not have a tail pipe, I have read EVs require significantly more energy to manufacture than similar sized (ICE) internal combustion engine vehicles. Then there is the question of how clean the power sources are that are used to charge them. In the 13-state PJM grid that stretches from Chicago to Virginia, and which also serves my own home, only 3.3% of energy is generated from wind power and 0.5% from solar energy. With so many of our largest corporations claiming they use renewable energy, I have to wonder how much of the 3.8% is actually available to charge my ‘green-powered’ EV when I plug in?


Geoffrey Pohanka is a third generation automobile dealer.                                                                                                       

He is Chairman of the Pohanka Automotive Group, located in Capitol Heights MD.                                                                                                                          

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