Constructing EV Charging Stations

By Ken Thomson

Building EV charging stations for public and private customers enables the contractor to facilitate a host of people transferring their vehicular power away from fossil fuels and towards electricity. EV charging stations have been springing up left and right as more and more drivers opt to purchase hybrid or all-electric cars, trucks and SUVs. As accessibility to recharging stations continues to grow, the momentum is apt to snowball.

The construction of EV charging stations is relatively straightforward. Most of the interfaces are prepackaged units available from several suppliers. The contractor's job is to set up the interface, ensure that all standards and safety regulations are met and work out parking and accessibility options with the station owner. Comparatively, natural gas filling stations are more complicated to construct, primarily due to accommodating the tank, controlling moisture content and the greater number of interfacing options to choose among.

There are a number of details that have to be worked out and a number of choices made in the process of building an EV charging station. At a high level, one has to establish whether the installation is public or private, residential or commercial and the number of parking spaces with access to charging interfaces. At a lower level, one has to calculate charging capacity, determine means of access and set the charging standard.

A private station is appropriate for commercial vehicle fleets and also for individually assigned use at residences or places of employment. Public accessibility implies that there needs to be an interface equipped with a universal form of billing. Public stations also typically need to provide more than one charging level option.

Often when a new technology is introduced into an existing environment, some amount of alteration is necessary. In the case of bringing EV charge capability to a building, one may have to consider laying extra conduit, adjusting electrical loads and changing parking assignments. For multiple users, such as in a condominium or office building, additional measures might be in order, such as individualizing power usage records. Construction contracts in such cases need to spell out the terms of tenant improvements, especially if uninterrupted continual use of the space during construction is required.

The owner of an EV charging station must anticipate the number of simultaneous users and acceptable charge time to order his supply equipment to match the needs accordingly. Currently there are two levels of service widely available. Level I operates at 120 volts AC and a maximum current of 15-20 amps. Level II uses 208/240 volts AC and currents of up to 80 amps, though some circuits are limited to 32 or 40 amps. Level I is adequate for distances less than 30 miles, taking about 4-6 hours to recharge. Level II recharges roughly 4 to 5 times faster than Level I.

There is also a DC fast charger, the availability of which is currently rather limited, that allows vehicles to recharge up to 80% capacity within a half hour. However, its power draw is excessive enough that a battery buffer may be required, enabling it to deliver 50 kW to the EV while drawing 20 kW from the grid.

There are some other issues EV charging station owners should discuss with their general contractor. For example, off-grid solutions can be installed under certain circumstances, such as solar panels mounted on carports, rooftops or stand-alone structures. In some cases, unused power can be sold back to the utility. Another option is to connect to a special EV network grid, the power for which is 100% from renewable energy sources. For on-grid applications, it may be possible to implement a "smart grid" arrangement whereby charging is reduced at peak load hours and/or initiated at low-cost times.

Facility Builders has been the construction manager for many EV charging station projects. Our company is a leader in the green building movement and we are set up to facilitate LEED certification. Our emphasis on communication and pre-construction services results consistently in buildings delivered within budget and schedule to satisfied customers. Please consider contacting FB&E today.