Summary: Switching Remote Dispensers – The Right Answer for M/HD EV Fleets

Joseph Gottlieb, CTO, Tuesday Sept 21, 2021

As we have spoken about in several of our recent blogs, the procurement, installation, maintenance, and operation of electric vehicle (EV) support equipment (EVSE) is a large component of medium- and heavy-duty (M/HD) EV total cost of ownership (TCO). And while the price of chargers is often what customers first think about, the installation of this equipment for fleet M/HD EV operators is a significant cost. Let’s look at two scenarios: one with four dispensers per Power Control System (PCS) connected in parallel, and one with four dispensers per PCS connected serially using Rhombus’ Sequential Power Switching (SPS) technology. We will also assume that the average cable run is in the parallel scenario is 200 ft.

  Metric Cost Each Parallel Scenario SPS Scenario SPS Savings
Qty Total Cost Qty Total Cost
# of Dispensers $7,500 100 $750,000 100 $750,000 $0
# of PCSs $30,000 25 $750,000 25 $750,000 $0
# of HV DC External Switches $5,000 25 $125,000 0 $0 $125,000
# Trenches (200 ft avg length) $4,000 100 $400,000 25 $100,000 $300,000
Total Cost $2,025,000   $1,600,000 $425,000

As you can see, the EVSE cost for the SPS scenario is $425,000 less than the cost of the parallel scenario. This is a 20% reduction in EVSE cost, or a reduction of $4,250 per vehicle. When rebates are figured in, the reduction is even more. For instance, just adding in the SCE Charge Ready Program Rebate for 25 chargers in the 51kW-150kW range ($512,500, or $5,120 per dispenser) reduces the cost of the parallel scenario to $1,513,000, and the cost of the SPS scenario to $1,087,500. The $425,000 savings between the parallel scenario and the SPS scenario then represents a reduction in EVSE cost of over 28%. That is what makes the SPS capability attractive for M/HD EV fleets.

If you are looking for made in the USA high-power DC fast charging systems for those EVs, look to Rhombus Energy Solutions. Our market-leading bi-directional EV charging systems (which are designed from the start for the needs of fleet operators) are designed and built in the USA. Rhombus also excel in the design of high-power smart inverters for next-generation renewable energy and energy storage deployments. Our expertise in energy management system (EMS) software is also embedded in our VectorStat EMS controller and software which is embedded in our EV charging systems and smart inverters. We have built over a thousand V2G-capable high-power, high-reliability chargers and bi-directional smart inverters for a variety of different sizes and classes of EVs

Find out how we can help you by contacting us at, or by reading our Vehicle to Grid Solution Brief.