How charge management can reduce OpEx and CapEx for EV fleet projects

  • Charge management software optimizes charging based on the available power, the schedules of the vehicles and the cost of electricity—from the rudimentary systems built into chargers to highly sophisticated systems that integrate with micro-grids or depot management.

  • The amount of peak reduction a CMS can deliver depends on the duty cycle of the vehicles. It ranges from 60% for school buses to 15 to 20% for more demanding use cases such as transit buses.

  • The time required for a local utility to provide a service upgrade can be a major bottleneck. A CMS can mitigate this constraint by maximizing the number of vehicles that can be served by the existing power capacity.

Q&A with The Mobility House Business Development Manager Sam Hill-Cristol

If there’s one topic that everyone in the EV infrastructure field is talking about these days, it’s charge management. As organizations of all sizes electrify their vehicles, they often find that power consumption is a major constraint. Charging stations, especially those that serve large fleets and/or heavy-duty vehicles, can suck up vast amounts of power, and simply plugging an array of chargers into the wall (so to speak) is not a good option.

Using charge management to manage power levels and charging times enables a fleet or charging provider to limit its peak power usage and thus lower its electricity bills, but it also offers several other benefits. Managing charging times can ensure that vehicles are charged with renewable energy as much as possible. Planning infrastructure projects with charge management in mind can allow companies to get their charging done with fewer and/or lower-power chargers, and it can help to avoid long delays in getting new electrical service set up by the local utility.

The Mobility House provides charge management systems to a wide variety of customers in Europe and in the US, including fleet operators, car dealerships, multi-family housing and workplace charging projects. Charged spoke with Business Development Manager Sam Hill-Cristol about how charge management works, how it can address the different needs of various types of customers, and how emerging technologies such as vehicle-to-grid and micro-grids fit into the picture.

Charged: As far as the terminology, I see charging management, load management, load balancing, smart charging…Do these have some specific meanings, or are they different terms for the same thing?

Sam Hill-Cristol: I’m not sure that everyone agrees, but we say charge management system (CMS), or charging and energy management—we usually throw energy in there to communicate that we’re controlling power flows. Some of those other terms refer to functions that a charge management system should provide. A useful CMS is a software solution that can provide load management, load balancing and even dynamic load management, which is a situation where the chargers are on the same meter as a building load, and we’re actually monitoring the building load and adjusting the charge limit based on the building load.

Charged: I’ve heard a lot about charge management systems, but I’ve never seen one. What’s the physical layout at a vehicle depot or a charging hub? Are there some servers in a shed that are connected to all the charging stations?

Sam Hill-Cristol: It varies. There are versions of charge management that are pretty invisible on the site. These are cloud-based and/or within the chargers themselves. They might do something simple like share power equally between a few chargers on a single circuit, depending on how many vehicles are plugged in.

A more robust charge management system—something that is more of a fit for fleets or multi-family, and can really help us attack the distribution grid limitations—that system has some hard-wired components and a local controller. A little controller, probably the size of your palm, sits on-site inside a weatherproof box. It has a 120-volt power supply and a switch, or maybe multiple switches, so you can connect a bunch of chargers to it.

That controller is hard-wired with Ethernet cable into every charger. It’s not daisy-chained from one charger to another—there’s no line where if you break communication with one charger, then you lose everything else down the line. We have what we call a ChargePilot kit, which is basically what I described, and we can just send that out to a site. And we typically work with an engineer or an EPC [engineering, procurement and construction] firm that knows our system. They can just install it, and it’s pretty straightforward. There’s also a router, so we can send data from our controller up to the cloud, to a user interface that the fleet can log into and see data and a live view of what’s happening on the site.

Charged: Is the software that makes all this work something that The Mobility House provides, or could that be a commercial product that’s available from different vendors?

Sam Hill-Cristol: Certainly there are options, but yes, The Mobility House provides that software. What I just described, all of those physical components are relatively off-the-shelf, but the software is what’s proprietary and where all the intelligence lies. That’s what allows us to optimize charging based on whatever the available power is, whatever the limit is that the grid has, or a sub-panel has, the schedules of the vehicles and the cost of electricity. Now those are the three big, big things that we’re paying attention to, but how that’s optimized and which chargers are told to turn on when and how much, that’s the software that lives on the controller. Of course we can push updates to it from the cloud, but if you were to lose connectivity, you would still have that intelligence, and that charging management would still occur.

That’s the architecture of The Mobility House’s system, ChargePilot. It’s not the architecture of every system, but that’s what we see as a best-in-class charge management system, and that’s what you need from a reliability perspective.

We’re starting to see more RFPs that are just for charge management, that are isolating that as an individual category

Charged: Is there such a thing as a standalone, off-the-shelf software package that somebody could go out and buy?

Sam Hill-Cristol: There are third-party charge management companies like ours that are selling software as a service, and we do a lot of work with partners. Someone could come to us and say, “I want to buy your system and roll it out on a bunch of sites and resell it.” We do a lot of reselling work. I think that is a good model.

There’s also in-house charge management software that a charger manufacturer makes. The downside of that is that it only works with the chargers that that company makes, so you kind of get locked in as a fleet and you don’t have any flexibility to go buy new chargers, because then your new chargers won’t talk to your old chargers.

Charged: What kind of RFPs do you usually see? Do most customers want a full turnkey system, or do some mix and match products and services?

Sam Hill-Cristol: We’re starting to see more RFPs that are just for charge management, that are isolating that as an individual category. And if you are a sophisticated customer, like a transit agency, we see a lot of piecemeal procurement—we’re going to get the buses, we’re going to get the chargers, we’re going to get charge management, and we’re going to put a solution together that works for us. So we’re starting to see that increasingly, and seeing charge management broken out as its own RFP.

Even on some of the smaller municipal fleets, we’re starting to see this, as opposed to one RFP that’s for everything, or it’s just for chargers and they don’t even really talk about charge management. I think the industry’s getting a little more educated on that, but we still see the old type of RFP where they just say “Hey, let’s buy some chargers,” and don’t really think about the software at all.

That’s why we created our RFP Guidebook for charging and energy management. We saw that many fleet operators didn’t know the full set of questions to ask about what their charge management could or should do for them. There were actually several RFPs that went out in the last couple of years that didn’t evaluate or differentiate for charge management comprehensively, and they had to start over and try again. 

Charged: The classic story is that a fleet buys a few EVs, they buy a few chargers, and after a while they realize that they need expert help to get their system organized. Would you say that’s a thing of the past, or are you still seeing fleets that don’t understand the need for charge management?

Sam Hill-Cristol: I would say it’s still there, but it’s changing, and a lot of our job has been market education. Certainly in the school bus space, transit space, municipal space, I think we’re starting to see a shift towards a more complete approach—people kind of learning from the first wave and thinking a little more critically about all the pieces of the puzzle.

I would say that charge management was not considered as one of the three pillars until recently. It was seen as within the chargers themselves, and now it’s starting to be seen separately.

Charged: Would you say that charge management is analogous to a company’s IT department in the sense that a smaller company might buy a turnkey system, whereas a larger, more sophisticated customer might have their own in-house people that run the system?

Sam Hill-Cristol: I would draw that parallel more about the whole charging ecosystem. I don’t think there’s any fleet out there, as sophisticated as they are, that’s putting together their own charge management system. I think the sophisticated fleets are putting together their own charging ecosystem of vehicles, chargers and charge management, and they’re picking and choosing vendors. Whereas yes, a smaller fleet might say “Just give me the whole ecosystem. You give me the chargers, you give me the software, all turnkey from one provider.”

We don’t see anyone building a charge management system from components from the ground up. That just doesn’t make sense. We’re always selling a whole system, we’re always selling software as a service, but for more sophisticated fleets, we’ll sell just charge management. For others, we might tack on some chargers for them if they ask for that.

From an IT perspective, we certainly see more demanding security requirements from larger fleets. They’re more involved in that sense, but they’re still buying the whole turnkey software solution. They just might buy that separately from charging hardware.

Charged: Vehicles, chargers, charge management—could we call those the Three Pillars of an electrification project?

Sam Hill-Cristol: Yeah, I would say those are the three most important, and I would say that charge management was not considered as one of the three pillars until recently. It was seen as within the chargers themselves, and now it’s starting to be seen separately.

Charged: Some of the chargers do provide some rudimentary charge management.

Sam Hill-Cristol: Exactly. It’s sort of a spectrum of charge management from what I would call load sharing on a single circuit to a more advanced sort of site-level optimization that can look at schedules, costs, power limitations across a whole site, multiple sub-panels, multiple types of chargers; and even provide some ability to integrate with solar and storage, or a micro-grid, or talk to a depot management system that’s calculating schedules. You start to get to a pretty advanced level with different integrations. But it is a spectrum and there is a very sort of simple version that I think works when you have only a couple chargers.

Charged: So, the main point is to control our energy consumption. Can we put some numbers to that? Let’s say I have a fleet of 50 trucks or buses. How much power capacity am I going to need, and by what factor can I reduce that requirement by using charge management?

Sam Hill-Cristol: It really depends on the duty cycle of the vehicle, but if you say it’s a larger, mid-mile delivery truck, maybe you’re looking at a 50-kilowatt to 100-kilowatt charger minimum, and a 250 kW or even 350 kW charger could be needed. If you need that for every vehicle, you’re looking at 2,500 kilowatts, 5,000 kilowatts minimum. For school buses, often we’re looking at 19.2-kilowatt charging stations. So if you had 50 of those, that’s about 960 kilowatts. And that’s what you would expect to see if you just plugged in all of the vehicles at the same time.

With charge management, we can see anywhere from a 15 to 20% reduction in that peak, all the way up to maybe 60% for school buses in some cases that we’ve modeled. School buses are a use case that has a huge potential for charge management because their schedules are not very demanding. You might be able to bring that 960 kW peak down to 200 kW, because you’re spreading that across the whole night. For commercial trucks, it may be somewhere in the middle. Then for a transit agency, where you have really demanding duty cycles, the vehicles are on the road a lot, maybe you only see a 10-15% reduction. But even then, for a fleet of 50 transit buses, you’re looking at at least 5 megawatts or something in an unmanaged scenario, so even that relatively smaller reduction can have some pretty big cost implications.

Certainly that has operating cost implications—if you can reduce your peak by 50 to 60%, you’re going to save money on demand charges and reduce your electricity bill. But I think it also can have implications for the capital costs if you know what charge management can do for you up front. One thing I like to point out, which I think is not always talked about, is: What’s your ratio of plugs to power capacity? Because if you’re reducing your peak and maybe instead of 960 kW, you only need 200 or 250 kW, you might be able to buy fewer chargers. And if those chargers are of the type where you have 3 or 5 plugs for every power cabinet, you can still plug all the buses in.

You still get 50 plugs, but behind that is less power, and that’s a lot cheaper. We talk a lot about vehicle-to-charger ratio, but I think the right charging management system makes you think about your plug-to-power capacity ratio, and that might lead to a cheaper capital solution because you have that software control.

For a good management system, the key overriding parameter is operation of the vehicle. You can never sacrifice that. 

Charged: It sounds like school buses are at one end of the use-case spectrum and transit buses are at the other end.

Sam Hill-Cristol: Yeah, I think that’s right. It’s about how much the vehicle is on the road. What are the duty cycles? What’s the dwell time? Do you have any exceptions to standard routes? If you’re a municipal fleet you may have some emergency response—sometimes you need to respond to a snowstorm with your plow trucks. You can certainly get complicated and think about the edge cases, but generally, you have school buses or municipal vehicles that only operate during the day, they sit all night. And that really provides a ton of flexibility in terms of how many chargers you might need and how much you can optimize the charging, how low you can push the peak by staggering the charging.

But for a good management system, the key overriding parameter is operation of the vehicle. You can never sacrifice that. You get into the transit world, for example, you have a bus that’s running multiple routes a day, maybe it’s charging multiple times a day, you have to respect that. And so sometimes you say, “I actually can’t delay charging. I’d like to, it’s going to be expensive right now, but I have to charge.” The right charge management system pays attention to vehicle routes first and foremost, and then everything else flows from there.

Charged: It sounds like there’s quite a lot of consultation with a customer involved before they ever buy any chargers.

Sam Hill-Cristol: Yes, there can be. Maybe this makes us unique in the charge management world, I’m not sure, but we often come in on a consulting basis, provide some modeling simulations, guide the customers through. We’re not tied to any hardware, so based on a simulation of what we think their optimized charging schedules will look like, we come up with a 15-minute interval basis. And we can look at that in a lot of detail and say, “This is how many vehicles are going to be charging at one time. This is how many vehicles are going to be plugged in at one time, based on our assumptions around when the vehicles are operating. Here’s how many chargers we think might make sense, and here’s a couple hardware options.” We often provide that to all types of customers, but certainly to ones that have less capacity in-house, maybe less money to hire a large engineering firm that’s going to do a full feasibility plan for them.

Charged: I’ve talked to a number of people recently who say that getting electrical service hooked up takes a long time, and that can be a big bottleneck.

Sam Hill-Cristol: I think those people are right and smart. We are seeing a big crunch in a lot of the country, California being one big example. We’re hearing from customers about limitations in power capacity, about utilities saying, “We need two or three years to give you the power that you need.” We try to bridge that gap. We try to say, “First, maybe you don’t need as much power as you think you do.” That’s part of our work with the charge management system.

If you know what your charge management system can do, then you can actually have some confidence to say “Hey, I thought I needed a megawatt of power but now I only need 300 kilowatts, so maybe I can start my electrification sooner, and use charge management to bridge the gap between when I want to put these vehicles on the road and when the utility is ready to upgrade my service.” And then I can iterate. “Two, three years from now, I can raise the limit. Maybe my utility finishes construction, and now instead of 300 kilowatts, I have that megawatt I originally wanted, and I can shift my charge management system, change the limit that it has, and unlock more power.”

We see our system as enabling that sort of phased approach—it future-proofs the fleet so they can start now, they don’t have to wait. I have an example of a customer in New York City that is getting a bunch of buses through the EPA Clean School Bus Program, and the utility said, “We have under 100 kilowatts for you to use on our system.”

We put that in our model, and we tell them how many buses we think they can charge on that limited power, and then that gives the customer the tools to plan their deployment. They say, “Okay, I can put 18 of my 25 buses at this site with the power limitations, and the rest need to go to my other depot.” Otherwise, those buses would show up and they would try to put the chargers in, and they would run into a big issue. It can be hard to get that information from the utility, but once you have that knowledge, then you really have a constraint, and the charge management system can maximize that situation, as opposed to, in our previous example, 19 kilowatts per bus, that might only be 3 or 4 buses without the charge management.

Charged: So they can modify their plan and stretch out their procurement, but still move ahead.

Sam Hill-Cristol: Still move ahead, and not stretch it out as much as they would have had to otherwise. 18 buses is significantly more than 3 or 4, and you can take advantage of that limited power, maximize it the best you can. And then again, you don’t have to pull the charge management system out, you just change the settings when you have more power.

Charged: What about solar and storage? Is that something that could be part of your system?

Sam Hill-Cristol: We don’t develop solar and storage on our own, but we enable the chargers to talk to those other resources. If you just have solar, our system can interface with the solar and maximize charging based on the solar output. It can monitor that load. Then if you have a full micro-grid—solar, battery storage, a generator—our system talks to the micro-grid controller, and says, “Right now the micro-grid is producing this much power, so we have this much power for charging.”

We are kind of a layer of intelligence that enables the chargers to interface with other distributed energy resources, but we work with partners to develop those. I can share an example in Silver Spring, Maryland. There’s a transit depot down there that we worked on that has a full micro-grid, so it can charge a bunch of buses when the grid’s down, and we’re a piece of that puzzle.

Charged: I know that you’ve been involved with some vehicle-to-grid pilots. Are you doing that on a commercial basis or is that still mostly in the pilot phase?

Sam Hill-Cristol: I would say that we’re at an inflection point between pilot phase and commercial. We’ve done 10 pilots around the world, all of them in Europe and Asia. We are moving forward with two projects that we’ve announced that are going to be bidirectional in the US, and we hope to scale that using industry standards such as OCPP, open charge point protocol. But there’s not a big market for bidirectionality right now in the US, so we’ve done pilots elsewhere. We don’t want to keep doing pilots, but we also can’t get ahead of the market. In the next two years I think we’ll start to see more commercially viable V2G projects that are scalable, that aren’t just a proprietary system that you build for one project. Because you can’t roll that out across the country.

This article appeared in Issue 63: Jan-Mar 2023 – Subscribe now.

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