Workplace Charging – The Goldilocks Approach

Many companies are considering providing workplace charging for their employees and finding they are in new territory with many options to consider. We at Plug In America would like to share what we have learned having been involved for over 10 years in both using charging infrastructure as drivers and advising site hosts of all types in how to provide effective charging facilities.

Goals

There are many reasons a company may be considering providing workplace charging. It could be to attract and retain forward-thinking employees, to enhance a company’s “green” image, to gain points toward LEED certification, or to raise awareness of electric vehicles.

Our analysis and recommendations are based on the goal of using workplace charging to increase the adoption of electric vehicles, which ties in with many of the reasons we find companies are considering making charging available in the workplace. Even when this is not an explicit goal at a given company, understanding the issues presented here may be helpful in evaluating charging options.

We also want to minimize the cost to the employer while meeting the goal of encouraging increased use of electric vehicles. These considerations include infrastructure costs, operating costs, maintenance costs, and efficient use of employee time.

There is certainly no one-size-fits-all approach that fits the goals and needs of every company. The ideas presented here are meant to serve as a starting point, a baseline plan that can be used to inform the analysis of corporate goals, infrastructure considerations, and employee interests.

Terminology

Level 1 refers to charging at 120V. This can be from an ordinary outlet using a charging cord or from a dedicated Level 1 station that has the proper electronics and plug to connect directly to a plug-in electric vehicle. For long term loads, like charging a vehicle, the current drawn is generally limited to 12A, which yields 1.44 kilowatts (kW) of charging.

Level 2 refers to charging at higher voltage, 208V to 240V. This can also done from a 240V outlet (NEMA 14-50, for example) using a charging cord, but is more typically done with a dedicated charging station. The current limit for these stations is typically 30 to 32 amps (~7 kW), can be anything from 15A to 80A (up to 19.2 kW).

DC Quick Charge This charging method bypasses the vehicle’s on-board charging equipment and sends high voltage (300V to 400V) DC directly to the battery, at rates between 20 and 130 kW. These are expensive to install and operate and are typically used for road trips or other situations where extra charge is needed in a hurry, not for a workday charging session.
The “Just Right” Fee
Problem – Free Reduces Availability

Free charging sounds like the best incentive to get people to consider electric vehicles, but the cost of electricity is not a barrier to EV adoption. An exact comparison with gas depends on a number of factors, but think of driving on electricity as equivalent to getting gas for less than $1 per gallon. Free charging makes the cost benefit more apparent, but has a couple of problems. First, it sets an expectation that charging will always be free, something that generally isn’t sustainable. A short term pilot with free charging can be very effective in kickstarting awareness of electric vehicles, and some companies may want to continue to provide free charging even as EVs rise in popularity.

However, if free charging drives demand to a level that can’t be met, the resulting oversubscription can create problems that reduce EV adoption. Free charging motivates everyone to charge at work because it’s cheaper than charging at home. This means most of the energy and infrastructure costs go to giving people free fuel. In fact, people who can’t charge at home can’t depend on charging that’s oversubscribed and therefore undependable. This built-in conflict can even create a hostile environment at work. Who wants to get into a shouting match over fueling their car so they can get home? Therefore the only people who can use free charging are those who don’t need it because they have a more reliable alternative.

When free charging leads to oversubscription and reduces charging availability for those who need to charge, it discourages EV adoption among those who could most benefit from charging at work.
Problem – Overly Cheap Charging Can Hurt The Environment

Like free charging, billing at a rate that’s below the market price for electricity incentivizes shifting charging from overnight at home to charging at work during the day without a corresponding increase in adoption or use merely erases the many advantages of charging off peak, thus reducing the benefits of mass EV adoption.
Problem – Overly Expensive Charging Can Hurt Adoption Or Usage

Paid charging billed far above the cost of electricity will reduce demand by not incentivizing shifting charging from home to work, but it also erases the economic advantage of driving electric. People who can’t charge at home thus can’t use this as a way to make driving electric financially viable. This therefore will not increase EV adoption. Likewise it can’t substantially increase use of EVs if it makes driving electric cost more than burning gas.
Solution – Charge a Little Over Market Price

Paid charging billed just a little above local home rates. This extends the economic advantages of driving electric to those who cannot charge at home. It also eliminates the incentive to shift charging from home to work. Together these benefits reduce the infrastructure cost of providing charging at work and focus the benefits on those who need it the most.

Note that public charging is different; other issues are at play there.
What Technology To Choose?
Problem – Level 2 Infrastructure Requires Resource Management
A typical Level 2 charging station delivers enough power to add approximately 200 miles of electric driving range in a workday, far more than the average commuter needs to charge up. Thus there’s an incentive to take time out of the day to go out and shuffle cars so the next car can charge. Employees at workplaces with oversubscribed Level 2 chargers have developed dedicated mailing lists and sophisticated notification systems to coordinate swapping vehicles at charging stations.
In the long run, employee distraction is probably the most expensive cost in providing workplace charging, easily exceeding the cost of electricity and, over time, exceeding the cost of equipment and installation.
Problem – Simultaneous Level 2 Charging Risks Utility Demand Charges
If there’s enough Level 2 charging that shuffling cars during the day isn’t needed, then the vast majority of EVs will get their full charge in the first couple of hours in the morning. Because of this, compared to a more gradual charging method, a company’s exposure to utility demand charges is tripled or worse, another hidden cost that can exceed the more obvious electricity, equipment and install costs.
Problem – Different Models Draw Power At Different Rates
Different cars draw power at different rates from Level 2 stations. A car’s charge rate is determined by its on-board charger, typically either 3.3 or 6.6 kW1.
When demand for charging is high and turnover is required to get everyone charged, then the scarce resource isn’t the electricity, it is the opportunity to charge. Billing by the hour seems like the right choice to incentivize shared chargers use, but is unfair to the vehicles that charge at half the rate of others.
Problem – Networked Billing Rates Can Be Too High

Because electricity is so cheap, most current solutions for paid charging require billing at twice the cost of the electricity, or more, for the site owner to break even on costs. This varies by region and may be better (or worse) in specific areas. Paying double for charging may leave some economic advantage in driving electric for those who can’t charge at home, but it’s at best dramatically reduced.
Problem – Billing Systems Can Cost More Than They’re Worth

Billing is expensive because you have to have equipment that measures time and/or energy dispensed and connects to a network (with some exceptions2) to transmit the resulting billing information. The equipment to measure time or energy can be cheap, but processing transactions that average around $1 each is expensive. If the billing rate is set low enough to encourage use, it may be impossible to ever recover the incremental cost of the more sophisticated hardware.
Solution – Fixed Monthly Rate Parking Pass And Simple Charging Station
Billing

With Level 1 charging, billing can be handled by having employees pay for a parking pass at a fixed monthly rate that allows them to use the charging. Charging for 8 hours will yield about 35 miles of range, which is enough for most commutes. So the billing rate could be set to be just a little above the cost for 8 hours of Level 1 charging, or about 11.5 kWh. If someone needs only six hours, they are overpaying by 33%, which is still far better than paying double at a billed Level 2 station. Because charging takes most of the day, there’s no incentive to run out and shuffle cars around, and exposure to demand charges is also lowered3. EV drivers can do the legwork needed for enforcement by reporting violators to facilities. Facilities can then issue a warning or call a tow truck.
Hardware

Level 1 charging can be either simple outlets or actual charging stations.
Leveraging Existing Hardware

Simple outlets (NEMA 5-15 or NEMA 5-20) are very inexpensive and may already be available in employee parking lots. If already available, providing charging can be as simple as adopting policy for giving permission to employees to use the existing outlets. These outlets need to be on dedicated circuits, which need to be rated for at least 15 amps and preferably for 20 amps. They should be situated such that a cordset won’t cause a trip or ADA hazard.
Advantages of Dedicated Stations

Level 1 charging stations have a number of advantages. Charging stations use the J1772 connector which is designed for thousands of plug/unplug cycles, are weather-resistant, have built-in ground fault protection, and communicate the maximum safe charging level to the car. In addition, having to pull a cable out of the trunk, lay it on the ground where it gets filthy, and putting it away later gets old. Charging needs to be fast and convenient: 10 seconds to plug in and you’re done. This requires actual charging stations.
Cost Of Hardware Is Small Percentage Of Total Cost

Although Level 1 charging stations are more expensive than outlets, when installing new wiring, the cost of the stations may not add much to the total cost of installing charging infrastructure.
Level 2 For Increased Availability

Level 1 may not be sufficient to meet everyone’s charging needs, so some Level 2 should also be available but at a higher billing rate than Level 1. Low power Level 2 stations (12 to 15 amps) can be administered in the same way as Level 1 stations, using inexpensive stations and controlling access via parking passes sold at a slight premium to an assumed 8 hours of charging per day at the local daytime utility rate.
DC Quick Charging For Edge Cases

DC Quick Charging can also make sense as a safety net for those odd cases where someone needs to charge quickly. This could be on site at the workplace for large companies or just conveniently located nearby.
Summary

Generally speaking, workplace charging should consist of mostly Level 1 charging, billed at just above the cost of 8 hours of charging per day, with some Level 2 available at a higher billing rate. Even though Level 1 charging stations and installation may not be any less expensive than non-billing Level 2 stations, this will meet the goal of increasing EV adoption and use while minimizing infrastructure costs, utility demand charges, and lost employee time.

Source: PluginAmerica.org