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Why Energy Storage is Important for Fleet Electric Vehicle Charging

 (Rick Sanders, CEO, Tuesday, October 1, 2019)

Electrification of medium/heavy duty electric vehicles (EVs) such as transit buses and short/medium range delivery trucks is a rapidly growing trend. Bloomberg New Energy Finance forecasts that 60% of public transit buses will be electrified by 2040, up from 17% (426,000 vehicles) today. This trend represents a great way for transit systems and delivery companies to help the environment while reducing both their energy and maintenance costs. For large fleet charging hubs such as vehicle barns however, one of the biggest issues is the availability of enough cheap power from the utility grid when the vehicles are being charged. Since these vehicles typically operate during the day, charging usually starts in the early evening, which also happens to be the peak load times for utilities.

Additionally, the power demands of fleet charging locations such as EV vehicle barns can often exceed the power commonly available from the utility grid. While many of these sites are great candidates for renewable energy sources such as photovoltaic power, that power is generally available only during daytime hours, exactly when it is NOT needed. And even if that power is put back in the grid to offset consumption (and energy costs) later in the day, it doesn’t fix the inability of the utility grid to supply adequate energy.

The obvious answer to this issue is to integrate energy storage systems with the charging infrastructure. Since batteries and (most) renewable power sources are DC-based just like vehicle batteries, this should be a straightforward endeavor. However in practice, this is often more difficult than it needs to be. Most EV charging systems aren’t designed to support DC power inputs, and are not easily modified to do so. A still bigger problem is that these systems often do not possess the intelligence to perform critical features such as peak power shaving, load balancing, and/or power provisioning and forecasting. These capabilities have to be designed into the EV charging infrastructure from the start – they generally cannot be retrofitted after the fact.

At Rhombus, our mission is to help solve the world’s energy challenges by designing and deploying the most innovative and efficient power conversion and management solutions. We are experts in building intelligent, extensible, and reliable EV fleet charging infrastructure for the most demanding environments. We have 20 years of algorithm development for every operational requirement and offer budget flexibility by applying only the resources you require. Learn more at

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