ET25SWE0028 - V2X Round-Trip Efficiency Market Study

AESC, Inc. proposes to conduct a market study which will include a comprehensive review of vehicle-to-everything (V2X) capable electric vehicles (EVs) and electric vehicle service equipment (EVSE). The V2X application implies bi-directional (two-way) charging of an EV so that the EV may be used as an energy asset providing additional benefits to the grid, home, or load to which it is connected. The project will include the development of a simple, public facing reference document which will clearly define and quantify charging efficiency, discharging efficiency, and round-trip efficiencies associated with bi-directional charging of EVs in various V2X applications. Note, round trip efficiency (RTE) refers to the ratio of cumulative discharge energy to cumulative charge energy and may be confined to the EV battery (defined as DC-DC RTE) or to the entire EVSE + EV battery system (defined as AC-AC RTE). In the latter, charging and discharge efficiency of the EVSE is included. Special focus will be made on V2X adoption in HTR communities by creating a roadmap which will draw from on-going EVSE TPM research initiatives on power-sharing hardware to develop technology and financial recommendations that will facilitate implementation of V2X EVSE. Existing studies have investigated power losses of bi-directional charging in specific use-cases such as vehicle-to-grid (V2G) and vehicle-to-home (V2H) but a higher-level standardization methodology for quantifying and defining V2X round-trip efficiency has not been established. Energy efficiency ratings may refer to one-way conversion efficiency or round-trip efficiency, and each vary on a variety of factors such as power throughput, ambient temperature, and system boundaries. Since EV battery performance can vary greatly when driving due to acceleration and braking frequency, this market study will focus on EVs in stationary V2X use-cases. Informing the market of these factors should help developers design EVSE control algorithms which optimize charge schedules to align with the EVSE’s most efficient conditions. Performing this analysis will help inform policymakers in California of current industry standards for bi-directional charging so that minimum efficiency requirements for various programs can be established. Further, market end-users and relevant stakeholders can make informed decisions based on bi-directional charging performance characteristics to optimize operations resulting in energy efficiency.

AESC, Inc. will review literature and conduct secondary research to inventory research to date on this topic. Once we identify gaps, AESC, Inc. will compile all available information to create a clear landscape of bi-directional charging and the associated power losses of various V2X applications.