Part of Grid Network »

The Grid Professionals Group covers electric current from its transmission step down to each customer's home. 


EV Sales: "Warm and Fuzzy" Now.....But....

image credit: and a publicly available (non-credit) photo
W. Alan Snook, II's picture
President GRID20/20, Inc.

Given 25 years of entrepreneurial business experience at many levels, my daily focus remains on building relationships, supporting customers and team members, and holding tightly to core business...

  • Member since 2021
  • 21 items added with 9,714 views
  • Aug 2, 2021

EV Sales:  "Warm and Fuzzy Now"…BUT…


  Source: Zpryme, June 30, 2021


Surely there is a growing sense of excitement, enthusiasm, and optimism for those who espouse EVs presenting a meaningful Climate Change influence.   EV supporters, manufacturers, and many political leaders have to be encouraged when they see the eye-popping EV Sales stats that are unfolding in 2021.

While the mantra in support of EVs seems to be deeply rooted in Greenhouse Gas (GHG) emissions reduction, there are some interesting realities that we should be considering.

For example, residentially-installed EV charging stations typically occur without utility awareness.   Very simply, a new EV owner contacts his/her local electrician, and just like that a new EV charging station is added onto the grid-edge.   This activity is unfolding right now, all across the US (and abroad where EVs are gaining market share).


And, EV customers commonly re-charge their vehicles during the evening hours; when most transformers are intended to be cooling down from the load burden being serviced during the daytime hours.  

So what?  Well, each residentially-installed EV charging station introduces a new, unplanned electricity demand into the grid.  This unplanned (and typically unknown to the utility) demand is commonly equivalent to instantly adding the burden of 1 – 2.5 NEW HOMES onto the grid; depending upon the rate of re-charge selected by the EV owner.  It’s fair to conclude that instantly adding an entirely unplanned demand of 1 -2.5 NEW HOMES is substantial.   It gets VERY interesting when two or more EV owners have a residentially-installed EV charging station added onto the SAME upstream distribution transformer that historically services their respective homes.   And, a lack of appropriate cool-down times for a transformer asset is the recipe for accelerated End of Life (EOL).   Either of these examples, or the combination of the two, can quickly result in substantial transformer overload, and therefore sets the stage for imminent transformer failure. 

To make things more interesting, the US distribution transformer fleet is now DECADES-Aged...meaning that many of our transformers were deployed decades ago with no expectation of the now-present demand burden being created by today’s EV uptake.   Very simply, utility operators did not have ample forecasting information decades ago that would permit them to deploy transformers sized to handle today’s emerging EV charging station demand. 

This culmination is known as ‘unplanned load/overload’….and it is now proportionally growing throughout our AGING transformer fleets across America as our EV charging stations are being installed.  This unfolding reality is setting the stage for INCREASED transformer failures, and power outages, and fires/wildfires, and increased public safety and environmental risks.  

While many proponents are celebrating the emerging ‘successes’ of EV adoption, and eventual GHG emissions reductions designed to impact Climate Change, we are quietly posturing ourselves for serious challenges, costs, and potential disasters.

It is not fear-mongering to reveal the unfolding truth of imminent negative impacts.  It is not a scare-tactic to reveal that substantial unplanned EV charging station installations will undoubtedly over-burden our aging transformer fleet.  And, it is not nay-saying to suggest that EV charging stations are helping to posture us for major grid-edge impacts.

Rather, this entire perspective is being brought to light so that while we are delighting in our EV market adoption successes, we can appropriately and proactively realize and then address the unfolding collateral impacts of our celebrated “EV progress”.

Yes, utility operators are in tune with commercial EV charging station installations.  Yes, new transformer installations designed to create a nationwide public EV charging infrastructure will adequately and safely serve those needs.  BUT, the quietly emerging impact of residential EV charging station demand somehow remains an “off the radar” problem; just waiting to rear its ugly head one day in the form of a major problem, or by quietly creating an increased frequency of power outages that will ultimately escalate electricity costs for all of us.

Proactive, reliable intra-grid data is quickly becoming a dire necessity for our operators.  Advanced Meter Infrastructure (i.e., AMI, or smart meters) are NOT able to reliably deliver this needed intra-grid info.   

Our now-unfolding residential EV charging station matter is yet another perfect application for the time-proven/field-proven Advanced Transformer Infrastructure (ATI) technology; where reliable, unique, timely, accurate, granular intra-grid data is seamlessly driven by ATI from the field, to our utility provider’s existing operations systems. 

In closing, while we are celebrating our developing EV market adoption success, we must also apply adequate focus to the unplanned electricity demand that we are introducing onto our aging grid-edge assets.  Before we allow a good thing like EV adoption to become multiple bad things like a) drastically increased power outages, b) painful electricity rate increases, c) increased transformer failure/fire risk, d) potential transformer failure-catalyzed wildfire risks, and the plethora of bad news outcomes that all of these items ultimately impart upon our societies, our environment and our wallets, we must get wise to this developing situation. 

EV adoption is fantastic….it improves our ability to impact GHG emissions.   But we cannot continue a ‘blind-eye’ policy with regard to the undeniable impacts that EV charging stations present to our aging distribution grid architecture; nor the likely negative outcomes that will result from the aforementioned asset failures and associated impacts, damages, costs, risk of injuries/fatalities, etc.    

Awareness is the first step…admission of the issue is the second step…corrective actions is the final step.

This message is designed to create ‘awareness’ of the emerging EV charging station issues, and ‘awareness’ that today’s Advanced Transformer Infrastructure (ATI) technology is available to remedy this unfolding problem. 


Donald McDaniel's picture
Donald McDaniel on Aug 5, 2021

Two points, I argue day after MDM data is a very valid way to determine if transformers are becoming overloaded.  The second is that at our Cooperative, we are more concerned with infrastructure than individual transforms overloads.  If a transformer overloads we are aware and can track the load increase assuming 4 neighbors don't all install EV's on the same day.  But we are proactively changing our design standards to allow for larger primary and secondary.  The replacement of conductors is our main concern.

W. Alan Snook, II's picture
W. Alan Snook, II on Aug 16, 2021

Donald - Thanks for your shared comments, and your expressed perspectives.  Our experience with operators has suggested that GIS mapping may not always be as accurate as may be assumed, or hoped to be.   In those cases, the MDM data is plentiful, but it is inherently inaccurate regarding the upstream asset conditions.  Undoubtedly, every utility has differing degrees of meter-to-transformer mapping accuracy.  For those dealing with such mapping inaccuracies, Advanced Transformer Infrastructure (ATI) empirically alleviates this challenge, and ensures that the operator has access to a series of reliable data points including but not limited to load/overload/asset condition/dynamic intra-grid conditions/etc.  We find that ATI synergizes with AMI, thereby providing very reliable data inputs for seamlessly supporting operations, planning, etc.  By employing both ATI and AMI, GIS mapping issues can be identified and addressed; and ongoing ATI monitoring ensures that future GIS mapping errors will not develop, or at least they will not persist if they do inadvertently occur.   

We truly appreciate that you reviewed our article.  Cheers!

Chris Chandler's picture
Chris Chandler on Aug 5, 2021

"Adding the burden of 1-2.5 new homes on the grid" per EV.  Really?  According to whom/what?  EVs are up to 80% more energy-efficient than vehicles with internal combustion engines, which waste a vast amount of gasoline in producing heat, not forward motion. 

According to the USDOT Federal Highway Administration, the average American drives 37 miles a day.  The average EV gets between 3.5 and 4.2 miles per kilowatt hour (mpk), but to be sporting, let's roll with the low number-- 3.5 mpk.  37/3.5 = 10.6 kWh, or, 317 kWh a month (EVs that get 4.2 mpk use less).  In a year? 3,804 kWh. 

In comparison, on average a residential electric water heater uses between 4,600 and 5,082 kWh a year, per USDOE on  

According to the US Energy Information Administration, the average American home uses 887 kWh/month.  So, EVs do NOT use the same amount of electricity as one home, let alone 2.5.  On average, adding an EV to one's home (and the grid) will have less impact than a second hot water heater.

W. Alan Snook, II's picture
W. Alan Snook, II on Aug 16, 2021

Chris - Thanks very much for sharing many facts supported by the USDOT, the EIA, and the DOE.   In fact, I am in agreement with the facts that you listed.  Perhaps the article did an insufficient job of articulating the proper message.  We were not disputing any Efficiency-related items associated with EVs vs. Combustion Engine vehicles.   The Efficiency data regarding EVs is clearly advantageous, hence the ongoing push for EVs.   However, the point we desired to make is regarding the unplanned demand that is created by residential EV charging stations on their upstream transformers.   Depending upon the charging system (110v, or 240v)  and the corresponding battery, the charging periods will require anywhere from 5-19 hours.  This will deliver an unplanned demand that is equivalent to 1-2.5 homes of load during that charging period.  For those drivers that travel the avg. per day mileage you accurately noted above, they will most likely not recharge their EVs nightly...likely they will recharge once every 5-7 days.  So, the unplanned demand we are highlighting will occur at this 5-7 day interval (if only one residential EV charging station is being serviced by the upstream transformer).  The other potential factor in this equation is the time of day when recharging occurs.  Thus far, it seems more common for nighttime EV recharging -- in fact, it appears that some utilities actually encourage or even reward EV recharging that occurs at night.  But, the interesting fact is that transformers are designed with a necessary cool-down period being expected.  So, for those instances where an upstream transformer is loaded/overloaded during the daytime, then the residential EV recharge occurs at night, there is less cool-down opportunity for the upstream transformer.   This is where accelerated End of Life for the transformer enters the equation.      I'm hopeful this message helps to properly distinguish between the accurate Efficiency figures you cited, and the accurate Demand figures that we are citing.      

Thank you for taking time to read the associated article, and thanks again for then taking time to share your thoughts.  

Chris Chandler's picture
Chris Chandler on Aug 16, 2021

I've driven 150,000 electric miles thus far, and I, and nearly all of the EV drivers I know, charge every night, not once every 5-7 days.  It's just the prudent thing to do.  Most EV manufacturers recommend charging only to 80%-90% daily, and only charging to 100% when needed.  We arrive home, plug in, walk away and don't have to think any more than that few seconds about charging. 

People's plans change quickly, and it's best to be properly charged up when leaving every morning.

Matt Chester's picture
Matt Chester on Aug 17, 2021

Most EV manufacturers recommend charging only to 80%-90% daily, and only charging to 100% when needed.

I'm curious-- do you have a setting where you are able to instruct your EV to stop charging at that 90% level? And do you override it if you know you're about to take a longer trip and want to reach 100% ahead of that? 

Chris Chandler's picture
Chris Chandler on Aug 18, 2021

Absolutely! For some, it's on an app from the manufacturer, for others on a screen inside the EV. (The new Volvo XC40 Recharge even allows the driver to select the amperage used when charging on its app.) Some DC quick charging stations (also known as Level 3 charging) automatically stop when charging is at 80% of battery capacity, since slamming 480V power onto batteries isn't optimal--really just recommended for those longer trips--and really isn't good for batteries beyond that 80% threshold. Charging to 100% on a Level 1 or 2 charger doesn't require an override, just an easy change in the setting.

W. Alan Snook, II's picture
Thank W. Alan for the Post!
Energy Central contributors share their experience and insights for the benefit of other Members (like you). Please show them your appreciation by leaving a comment, 'liking' this post, or following this Member.
More posts from this member

Get Published - Build a Following

The Energy Central Power Industry Network is based on one core idea - power industry professionals helping each other and advancing the industry by sharing and learning from each other.

If you have an experience or insight to share or have learned something from a conference or seminar, your peers and colleagues on Energy Central want to hear about it. It's also easy to share a link to an article you've liked or an industry resource that you think would be helpful.

                 Learn more about posting on Energy Central »