Designing the Right Electric Vehicle Charging Depot

Plug n’ play may be suited best to music, but for electric vehicle charging, the opposite applies.

Determining, planning, and installing an EV charging depot involves three primary factors: Time, patience, and plenty of specific information. The more precise the goals and plans, the more success a fleet operation gains with connecting fleet vehicles, duty cycles, and efficient charging times.

For an overview of the steps in concept design and EV power planning, Charged Fleet recently spoke with an expert in this area. Jessica Cain is a professional civil and environmental engineer for Kimley-Horn, one of the nation's leading engineering, planning, and design consulting firms headquartered in Raleigh, N.C. Cain has more than 20 years of experience in the electric vehicle industry, renewable energy, and telecommunications. She has worked in a wide array of efforts that include the development of NEVI (national electric vehicle infrastructure) plans, the design and set up of public and fleet EV charging stations, and ground based and rooftop solar projects.

[The transcribed conversation below has been edited for length and clarity].

Big Charging Projects Overview

Q: Give us a brief overview of the two charging infrastructure projects that you have worked on for fleets.

A: I worked on two very different versions of fleet charging programs. One was for a utility client. They knew right from the start that they were interested in adding solar to provide an onsite source of electricity and leverage battery storage. This helps energy consumption from the grid at peak demand, and they wanted to use as much renewable energy as possible to power their electric vehicles.

The project included an extensive solar canopy and battery storage microgrid controller for over 40 charging stations. The chargers were a combination of level 2 and DC fast chargers for their fleet vehicles that typically drive 50-60 miles per day. The second fleet program that I've been leading for a national logistics company is a series of sites.

The goal is to use only the existing electrical capacity. We focused on level 2 charging stations for vehicles with routes that were typically 80-100 miles a day. That involved quite a bit of planning to ensure the right routes were paired with EVs.

Key Steps for Designs and Plans

Q: What are some of the key design and planning steps for an EV charging depot even before construction starts?

A: There was a lot of upfront planning for both projects, and they differ in approaches, timelines, and budgets. The first step is to understand the goals of the clients. What budget do they want to work within and what does success look like for them?

We start by discussing the use case. Is it for private charging? Is it publicly accessible but geared toward fleet vehicles? A combination? Do they have performance agreements and uptime guarantees that they have signed with private fleets that will use that site? And after that, two steps that go together are a site survey and evaluation and then early coordination with the utility company.

I can't stress enough that early on, it’s critical for the utility company to understand project timelines. We evaluate the electrical configuration of a particular site, work with a utility company to determine the current electrical capacity available for that depot site, and provide the additional load we're requesting in terms of chargers.

Then we work with the utility company to determine the cost and timeline the utility company will need to serve that request. In addition, we evaluate the entry and exit routes, the traffic patterns of the sites, the water patterns, and what subsurface features we might need to consider, especially where we're boring underground or adding large piers to support solar canopies.

Plus, we'll review the environmental permitting requirements, jurisdictional code, and design requirements. There's a lot that goes into it.

Advantages of a Sustainable Microgrid

Q: How do the power grid, battery storage, solar sources all work together to create a reliable charging depot?

A: A microgrid generates electricity onsite, which is typically done with renewables such as solar panels and sometimes also backup generators. Those generators might use a renewable source of fuel such as renewable types of propane, natural gas, or renewable diesel. You might see wind and often a combination of these generation sources. The battery energy storage system, which you'll also hear of called BESS (battery energy storage system), can store the energy generated and deploy it during outages or during peak demand.

You have a resilient site backup in the event of an outage, creating a reliable charging depot. It's the insurance policy that fleet managers are looking for.

Microgrid Versus Direct Power Grid Options

Q: For those fleet operations that only want to be connected to the power grid, what equipment and resources need to be in place for that?

A: If they only want to be connected to the power grid, you can still have those resources. You can still have solar and battery storage and be connected to the power grid. If you are looking at only the power grid without some of those onsite generation resources, you typically see large transformers and large switchgear supporting those facilities.

Q: Regarding the equipment and resources for a microgrid is there anything else that must fit into that equation?

A: The systems would have a microgrid controller, which monitors the status of the onsite generation, the power grid, the battery storage, and the loads. The loads are in the form of charging stations or other demands on the system. The controller can switch between the power sources. We work with clients to set objectives and priorities during the planning process.

It’s critical to determine what portion of the expected daily electricity consumption will come from onsite generation. Other keys for site operations are space and budgetary constraints, the needs and state of the vehicles, and their routes.

Without onsite generation, fleet managers must rely only on the power grid. We work to make electrification as straightforward as possible and enable fleet managers to leverage our insights from our previous experiences.

Lessons Learned from Installing EV Chargers

Q: What would you say are some of the primary lessons that fleet managers can learn from the experience of planning and installing EV chargers based on your observations?

You’re best-off working with a team to create a plan. Clearly outline the objectives and realize that you don't have to be at 100% electrification. If that's your eventual goal, then pick the deadline to achieve it. It's going to take some time, and work toward the milestones to get you there.

Also, what do you want your charging equipment and software platform to provide? What types of ESG or sustainability reports are you looking for? I'll say it originates with the utility company, and work that early into your plan and understand what the cost of upgrades might be and don’t be afraid to talk to others doing the same thing. Ask them also to share their lessons learned.

There are so many fleet managers going through this right now and there are some very real supply chain constraints now. Understand the equipment lead times of the charging equipment, the transformers, and the switchgear. It’s important at the start of a project and it varies depending on the area of the country you're in. Besides the equipment, your fleet project might take a year, 18  months, and in some cases over two years. So that takes design and installation partners to develop a plan, including a plan for operations and maintenance.