Driving Towards the Finish Line for Production Vehicle to Grid Deployments

(Joseph Gottlieb, CTO, Tuesday February 9, 2021)

In last week’s blog, we discussed why electrifying school buses was attractive from an air pollution perspective. But for electric school buses to “pencil out”, the higher acquisition cost must be offset by reductions in other costs such as maintenance costs (which we also discussed in the previous blog). One of the other opportunities for significant cost reductions is energy costs and while running a bus on electricity is less expensive than doing so on diesel fuel, vehicle to grid (V2G) can reduce energy costs even more. By taking excess energy from buses at the end of the day and putting it back onto the grid during peak hours, electric bus operators can “arbitrage” the electricity market and cut their energy costs even more. So what stands in the way of V2G becoming more widespread, and what is industry doing to overcome these issues?

Implementing V2G correctly requires a number of complex “handshakes” that must be implemented between utilities/grid operators, vehicle OEMs, aggregator software companies, and charging companies. Some of these include:

  • When to put how much electricity at what phase back onto the grid;
  • How much power is in available EVs;
  • When the vehicle will have to “go back to work”, and how much power it will need.

The vehicle OEM community, the EV charger community, and the aggregator software community have all been working hard on extending existing standards to simplify those interfaces. The last step is the handshake with the grid, which has drawn significantly from the experiences integrating stationary battery storage systems. ISO 15118 and UL 1741-SA are also good starting points for these efforts, as is the experience gained from pilot V2G programs. These efforts are blazing the trail towards the first production V2G deployments, which promise to further reduce the energy costs for operating electric school buses.

Rhombus has built high-power DC fast charging systems and smart 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 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 news@rhombusenergy.com, or by reading our Vehicle to Grid Solution Brief.