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Building Vehicle-To-Grid Power Storage Solutions for Fleet EV Operators

(Joseph Gottlieb, CTO, Thursday, May 21, 2020)

Our last blog explored the use of vehicle-to-grid (V2G) for energy storage. Let’s delve a little deeper into V2G, and how fleet electric vehicle (EV) operators might utilize V2G as a part of their high-power EV charging infrastructure. As we pointed out in our last blog, V2G implementations require chargers that are bi-directional. More specifically, bi-directional chargers in North America need to conform to the UL 9741 specification. UL 9741 specifies the interface between the bi-directional charger and the utility grid, allowing the grid management system to control the output of stored energy from the vehicle to the utility grid. However, having UL 9741 chargers as part of your charging infrastructure alone does not give a fleet EV operator a viable V2G solution – fleet operators have to determine what they want to get out of a V2G solution.

The most straightforward way for fleet EV operators to utilize V2G is to reduce their energy costs by putting power back onto the grid during peak hours. As vehicles return to the vehicle yard (usually for most fleet operators, this is in the early evening during peak hours), the power remaining in the vehicles is put back onto the grid at a high price. After peak hours are over, the vehicles can be recharged at a much lower price. The result is significantly reduced energy costs. This is the most common use case for V2G, but there are other possibilities depending on how the EVs are operated. For instance, school bus operators could “rent out” the energy storage capacity in their buses during the weekends and the summer when they are not being used.

As a leader in the development and manufacturing of bi-directional, high-power energy systems for both vehicle charging and photovoltaic solar applications, Rhombus is an expert in high-power charging systems for EVs, and especially in the area of vehicle-to-grid (V2G) charging. We have built hundreds of V2G-capable high-power, high-reliability chargers 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 Energy Storage Reference Architecture white paper.

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