Combining the Demands of V2G With M/HD EV Fleet Charging

(Joseph Gottlieb, CTO, Tuesday October 20, 2020)

If fleet charging for M/HD EVs wasn’t complex enough, many of these operators are now beingrequired to support vehicle to grid (V2G) operation, such as school bus operators and public transit bus operators. The positives of V2G are compelling: reduced energy costs and ability to support the grid during peak hours. However, implementing V2G is very complex, for everything from managing dozens of vehicles to the bidirectional charging hardware required to the vehicle interface software stack to the grid electrical interface to the utility supply/demand interfaces. Then throw on top of this the extra certifications required for V2G operation, and you have a set of charger requirements that is fundamentally different and more complex than what is required for either consumer or commercial auto chargers.

Since many of the V2G complexities impacting M/HD fleet EV chargers are not yet solidified, M/HD EV chargers must be “malleable” enough to evolve to the changes that will occur as the V2G ecosystem matures. Rhombus chargers embrace this philosophy on several levels. We support a variety of physical control interfaces for our chargers, enabling our systems to work in a number of industry-standard configurations. We also support a number of industry-standard communications protocols, simplifying interconnection with different control systems. Finally, the software in our chargers is also highly adaptable and can run new plugins or third-party applications. The result is an M/HD EV charging infrastructure that will meet the need of fleet operators both today and in the future.

Rhombus has built high-power inverters for renewable energy such as “behind the meter” grid energy storage systems for several years. We have applied that expertise to the design of our latest-generation bi-directional electric vehicle (EV) charging systems (which are designed from the start for the needs of fleet operators) and bi-directional smart inverter systems for microgrids. Rhombus 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. Rhombus also excels in the design and testing of high-power electrical equipment to meet the requirements of UL and other certification organizations. We have built hundreds of 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.