Are electric vehicles a viable alternative to home batteries? An Australian case study

Electric vehicles (EVs) are increasingly being integrated into energy systems due to their potential for bidirectional energy flow, particularly in vehicle-to-home (V2H) applications. While conventional home battery storage systems remain a popular solution for increasing self-consumption of photovoltaic (PV) generation, the feasibility of using EV batteries as an alternative to home batteries for residential energy management remains an open question. This study investigates the viability of using EV batteries as an alternative to home batteries, with a primary objective of minimising electricity costs. An optimisation framework is developed to evaluate 30 unique scenarios, combining six different driving behaviours and five distinct load demand patterns. The EV availability constraint, a key challenge in V2H integration, is incorporated into the model, distinguishing it from traditional home batteries that remain permanently available. The study also explores the impact of EV battery capacity, with the analysis conducted on various battery sizes ranging from 20 kWh to 120 kWh, under different time-of-use (ToU) tariffs. This provides valuable insights into the potential of EV batteries as a cost-effective and flexible alternative to home batteries. The findings show that an EV battery can achieve a lower annual energy cost than a home battery; however, this advantage is only evident when the prosumer has an EV battery capacity of at least 45 kWh, a short travelling distance, is available around noon, and has higher energy demand during the evening. • This study investigates EV battery viability as alternative to home batteries. • Optimisation framework evaluates scenarios with varied driving, load, and ToU tariffs. • EV batteries can lower annual energy costs compared to home batteries. • An EV battery capacity of at least 45 kWh is required for cost reduction. • Benefit evident with short EV travel, midday availability, and high evening demand.