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A Reference Architecture for Integrating Energy Storage in Fleet EV Charging Infrastructure

(Rick Sander/ CEO and Joseph Gottlieb/CTO, Tuesday, April 22, 2020)

While 2020 will likely see flat electric vehicle (EV) sales, the long-term trend of EV market penetration is still expected to accelerate over the next ten years, both as a percentage of vehicle sales and in absolute numbers. The cost of lithium ion batteries are expected to drop by 60% over the next decade, and vehicle manufacturers are moving ahead rapidly with electrification. Within vehicle fleets, electrification is growing even more rapidly, with the only exception being Class 8 long-haul trucks, where range and refueling times are an issue.

One of the likely issues that will develop as fleets electrify is a lack of utility grid power to support electrification. This is especially true for medium/heavy duty (M/HD) EVs, which often have battery capacities 8x-10x that of cars and light trucks. While a single 2MW power feed might be enough to charge 20-30 of these vehicles at night, it is woefully inadequate to charge 100-200 of these vehicles. One way to address this issue is to combine energy storage resources with the fleet charging infrastructure at the point of consumption – the “vehicle barn”. This approach has several benefits, including enabling the use of photovoltaic (PV) solar power by storing that energy during the day, and utilizing energy cost arbitrage approaches such as peak shaving to time-shift power consumption from peak hours (which is when most EVs would “naturally” recharge) to the day or to late-night “super-off-peak” hours which reduces EV energy operating expenses. Today, Rhombus released a reference architecture that describes these issues, and how energy storage at the vehicle yard can mitigate the utility grid power availability issues. You can read our press release and download the reference architecture here or from our website.

As a leader in the development and manufacturing of bi-directional, high-power vehicle charging systems, Rhombus is dedicated to helping customers bridge the power gap and electrify their vehicles. Our VectorStat® hardware and software allows fleet customers to gather data from all of their infrastructure  nodes, regardless of connectivity or network issues, to effectively manage their energy resources. VectorStat’s applet-based open architecture also enables the easy integration of new features and functionality, whether to support new hardware or to provide cutting-edge data analytics capabilities. Find out how we can help you by contacting us at

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