Will My EV Crash the Grid?

Bailey Nolting Uncategorized

Pete Westlake, Manager New Products and Services, Orlando Utilities Commission

June 2024

As we ponder the transition to Battery Electric Vehicles (BEVs), a pressing question arises: Will the widespread adoption of BEVs strain our power grid beyond capacity? Could plugging in my BEV be the tipping point for our beloved electric grid, upon which we rely for countless daily activities? While this concern is voiced by personal BEV owners, it looms even larger for commercial fleet operators. Let’s explore this issue in greater detail.

Fuel Generation Capacity

First, let’s examine a few concepts for energy as it applies to BEV charging. Utilities can flex up and down to meet customer demand. However, we are required to maintain the capability to serve our peak demand plus 15% to 20% reserve at all times. Demand fluctuates based on consumer needs, with peak power demand usually occurring between 4:00 p.m. and 7:00 p.m. in the summer – when people return home, use appliances, and charge their cars. As night falls, electricity usage decreases.

When our demand peak is lower, we can use the excess capacity to serve higher loads for our customer base, sell that capacity on the open market, or reduce our generation of electricity.

The graph below shows the demand peak for July 5, 2017, before a significant number of BEVs were added to the grid. As you can see, we can generate more than we need many times throughout the day. We have assessed vehicle registration data in Orange County, Florida, revealing that there are 1.2M registered vehicles. This represents a total demand of 15,600 MWh/day. OUC’s current daily capacity is 39,840 MWh/day, and our current load is 19,785 MWh/day. If we can control when this demand happens during the day, we have more than enough capacity for the foreseeable future for BEV charging.

Fuel Requirement for BEV

How much energy does the average BEV consume? Typically, an individual drives around 13,000 miles annually, averaging roughly 35 miles per day. Although this figure may double or triple for certain commercial applications, let’s stick to a conservative average of 40 miles daily. With typical vehicle efficiency at around three miles per kWh, this equates to an average requirement of about 13 kWh per day per vehicle.

Residential BEVs

In a typical home, the fuse box can be rated anywhere from 100 to 400 amps. For this example, we will use a standard 200-amp panel.  This panel can handle up to 48 kW of demand at any time. The average household typically uses two to 20 kW/hour depending on what appliances are active in the house during that hour. 

Over the full day, a home will use between 30 and 100 kWh. Panel capacity could theoretically reach up to 1,000 kWh/day (assuming full load throughout the day, this is not the case for a typical home). So, while adding four BEVs (52 kWh/day) might double a home’s daily usage, it shouldn’t cause significant issues. However, simultaneously charging all vehicles at peak demand could overload the panel with dire results. For example, plugging in four BEVs may add as much as 36 kW, leaving 14 kW for the home. If this were to occur at a peak time, this could cause the fuse panel to overload.

For residential usage, the grid is designed to accommodate such loads, provided consumers charge their cars during off-peak hours. Time-of-use (TOU) rates incentivize this behavior. TOU is where prices vary based on the time of day, highest when electricity demand is high and low when it is not. Homeowners, however, should assess their breaker panel’s capacity, especially with multiple electric cars. As highlighted above, charging several vehicles simultaneously without safeguards could overload the panel. We do not feel that residential load due to BEV adoption will adversely affect the grid.

Commercial BEVs

Commercial fleets pose a more intricate challenge. Despite representing only 1% of total vehicles, their mileage can be significant, though unlikely to exceed 10-15% of the total miles driven in the U.S. According to estimates from the alternative fuel database, out of the 2.8 trillion miles driven, only 3 billion miles are attributed to commercial vehicles. Just as we examine local infrastructure for residential needs, the same applies to commercial settings. It’s more probable that we won’t have sufficient power available at fleet sites than the fleets outpacing our generation capability. This is why we ask our customers to engage the utility when electric vehicles are starting to be considered, not after they are purchased.

To appropriately analyze commercial fleets, we need to consider more than just range. We must also look at factors like mileage, duty cycle, and rapid charging. However, for this analysis we can assume most vehicles will charge overnight during off-peak hours aligning with residential load patterns. So just as residential charging is not likely to adversely impact the grid, so it is for commercial customers. But, just as with residential charging, the biggest potential issue is “how much power do I have at my disposal.” If it is less than I need, then it will take time to provide that additional power by the utility. And the time needed to address the issue depends on the constraint and whether you are compelled to add a transformer, secondary, or substation.

A few fleets will require rapid charging due to the need for quick turnaround vehicles such as emergency response, long-haul trucking, and truck rentals. For rapid charging, we may need to consider onsite battery storage. Battery storage allows us to flatten demand, ensuring a consistent draw from the grid while supplying the charging equipment during peak times. This is an important factor because, for OUC, the peak demand is a fixed charge based on the highest peak demand for any 15-minute interval during the billing period. This makes managing demand peak a critical part of the electrification of transportation.

So, what does all this mean? We have some good news: Long-haul fleet electrification isn’t likely to occur soon, except for specific routes where infrastructure is available. This means that the majority of charging will occur “behind the fence,” most likely overnight. Consequently, it’s unlikely to strain the grid, except for concerns about the power capability at specific fleet locations. This issue may be problematic and is likely to take time to resolve. For example, it can take months to replace a transformer and years to provide additional power capacity at the location. There may be some very densely populated areas like Manhattan, where this is even more difficult to address. However, for the lion’s share of cities, providing power is achievable assuming we have the appropriate time to prepare. This highlights the need for fleets considering electrification to engage their utility as soon as possible.

Pairing Solar with Charging

We have more good news if we are successful in pairing solar with EV charging. In OUC territory, solar is growing at 1,500 kW per month, and currently has a capacity of 90 MW at peak during the day. Charging predominantly occurs at home or work. Home charging will take up excess capacity overnight, while workplace charging presents an opportunity to leverage excess solar energy produced during the day. The pairing of charging solar during the day and excess capacity overnight makes BEVs a great benefit to the grid, not a risk.


I wish I could say that this is the end of the story. Unfortunately, the electrification of the transportation market isn’t the sole concern. This issue needs to be viewed from a higher level. 

We are experiencing unprecedented growth in the utility industry, including data centers, cryptocurrency mining, and indoor grow farms, among others. The convergence of these new load growth industries will directly impact our ability to supply power. Additionally, our traditional method of power generation, in part, involves burning fossil fuels. Most utilities have 2030 and 2050 net-zero carbon emissions goals in place, meaning we are transitioning toward greener energy sources like solar and wind. 

The good news is that transportation offers the best pairing between supply and demand. Typical charging occurs overnight when grid demand is lower, or it can be paired with solar production during the day using workplace charging. This makes transportation an ideal candidate for managing load growth.

In essence, the impact of BEVs on the grid depends on our current decisions and processes. Thoughtful charging practices, along with innovative solutions like storing solar energy in car batteries, can alleviate grid strain. Conversely, haphazard growth without load management could necessitate significant grid expansion. To optimize this transition, we must strategically pair electricity production with consumption, which presents a historic opportunity that can potentially drive down rates by maximizing asset utilization.  

So, to answer the original question, will my BEV take down the grid? The answer is no… presuming we expand this new growth thoughtfully.

  1. https://www.fhwa.dot.gov/ohim/onh00/bar8.htm
  2. https://afdc.energy.gov/fuels/electricity-benefits