Electric Vehicle Charging at Work

Electric Vehicle Charging at Work

Ryan Winn

Workplace site hosts are investing in plug-in electric vehicle (PEV) charging infrastructure for their employees and tenants, but the impact of their investment decisions on behavior and usage are still not yet fully understood. Insight into the interdependency of pricing, behavior, productivity, usage, and investment decisions can help to achieve a balance between the needs of all three primary stakeholders (PEV drivers, site hosts, and utility providers), each of which have their own objectives interacting with the charging infrastructure. While a PEV driver wants the flexibility to charge when and where they want, utility providers want PEVs to plug in when there is an abundance of renewables and sufficient local capacity. Site hosts have a variety of goals, including maximizing vehicle turnover, operating a cost neutral resource, offering free charging as a building amenity, promoting company sustainability goals, among others. PEVs can be utilized as a grid management resource if drivers are compelled to shift usage patterns through appropriate pricing incentives to times when the marginal cost of supplying energy is lowest. Peak energy periods occur during work hours in the middle of the day when vehicles are parked idle for extended periods of time, and therefore including workplace site hosts in these discussion are critical to provide maximum cumulative benefits and align the interests of all players.

Previous research conducted on workplace charging has been limited to qualitative analyses looking at case studies and best practices to help inform employers more generally on the benefits and drawbacks of free workplace charging. This report instead quantitatively analyzes almost a half million workplace charging sessions over the past five years within Southern California in order to answer the following: How do workplace site hosts’ pricing policies and investment decisions influence PEV drivers’ behavior, and what are the consequences of their decisions on public policy?

In order to quantify the behavioral and usage effects of how PEV drivers interact with charging infrastructure, this report analyzes charging sessions conducted on ChargePoint’s network at Southern California worksites that includes information on session timing, active charging time, energy drawn, and fee charged, among other statistics. From this data, a collection of utilization and performance metrics were derived to describe charging behavior and evaluate the effects of different pricing policy components and investment decisions on charging efficiency and overall usage. Regression analyses were then conducted to isolate the effects of different pricing policy components as well as compare the six most common types of policies observed. These same metrics are then used to analyze usage trends before and after the 27 worksites identified as investing in additional charging stations to determine trends and describe how workplace charging influences PEV adoption rates.