EV Charging Utilization Rate: Time to Standardize the Definition?

When a charge-point operator (CPO) states that they have a utilization rate of 21%, do you know what that actually means?

One of the challenges of new or maturing industries is that they often lack standardization on simple things such as terminology and metrics. We've reached this same point of inconsistency in the electric vehicle (EV) charging industry.

Time-Based Utilization Rate

"Utilization" is not a term just used in the charging ecosystem. The professional services industry, for example, uses the "utilization rate" metric to calculate how billable employees are: Billable hours ÷ total hours x 100 = utilization rate

With time-based charging utilization, the standardized denominator is the number of hours a charging station is open to EV drivers. For most stations that is going to be 24 hours. The resulting rate calculation (percent utilized) is normalized and can be benchmarked across internal or competitive charging stations.

Bill Ferro, Paren CTO, feels even more strongly about time-based utilization arguing that this rate is fundamentally about measuring the user experience.

The Problem With Throughput-Based Utilization

When it comes to using the throughput (kWh)-based utilization metric, it becomes difficult or perhaps impossible to have a denominator that can be used to benchmark across your portfolio or against competitors. There are simply too many variables, including power level, throttling, shared power, maximum charging rate of the EV, charging curve, battery state, and more.

Session-Based Utilization

A third potential utilization rate calculation would be based on session volume. The problem is that the number of potential sessions in a daily period can vary based on most of the variables outlined above. This metric provides value to CPOs on an internal portfolio basis but is difficult to benchmark across companies.

Stations, Stalls or Ports?

From an industry benchmark perspective, we at Paren argue that utilization should be calculated at the station level. As a CPO, whether a charging station has 2 or 24 stalls, what matters is the total utilization and revenue from the site.

What do you think? Share your thoughts here on charging utilization rates and if the industry should work together on a standardized metric definition.

By Loren McDonald, Chief Analyst