A new Australian study has found that electric vehicles (EVs) equipped with vehicle-to-home (V2H) technology can significantly reduce household electricity costs and lessen the need for large, costly home battery systems.
The research, led by experts at Flinders University, Adelaide University and Murdoch University, investigated how using an EV as a mobile energy storage unit influences the optimal sizing of rooftop solar (PV) and home battery storage in grid-connected residential homes.
By treating the EV as a mobile energy storage unit, V2H enables households to use stored EV energy to power appliances during expensive peak-demand periods, slashing grid imports and boosting energy efficiency.
The study analysed three residential energy setups:
- Solar + battery + EV with V2H
- Solar + EV
- EV only
Under the most efficient configuration (the first scenario), the researchers found that a 7-kW solar system paired with a 9-kW home battery delivered the lowest annual electricity cost of $2451.
The cost of electricity dropped to 27 cents per kWh and grid electricity imports fell by 78% compared to a house with no solar or battery.
When V2H capability was removed, the home required a larger 13-kWh home battery to achieve a similar performance, resulting in a 10.8% increase in annual electricity costs.
Lead researcher Ms Golsa Azarbakhsh, from Flinders University, says the results highlight the growing role that EVs play beyond transport.
"Our work shows that enabling electric vehicles with V2H technology can play an important role in supporting renewable energy use in homes," says Ms Azarbakhsh, a PhD candidate at Flinders University's College of Science and Engineering, Tonsley campus.
"Vehicle-to-home capability can reduce the need for dedicated home battery storage while lowering household electricity costs by about 6.8 per cent."
Research collaborator Dr Solmaz Kahourzade, from the University of Adelaide, says the findings reveal the value of V2H in the Australian energy landscape.
"South Australia already has some of the highest rooftop solar uptake in the world, but many households still depend heavily on the grid during peak times," says Dr Kahourzade.
"If we want to accelerate electrification and reduce energy bills at the same time, V2H is one of the strongest tools available."
The study used real electricity tariffs, weather data and household load profiles from Adelaide, incorporating uncertainties such as EV arrival times, departure times and battery charge levels. It also accounted for South Australia's 1.5 kW export limit for residential solar systems.
Under these realistic conditions, V2H improved solar self-consumption, reduced grid reliance and delivered year-round benefits - particularly during winter, when solar output is lower.
"With EV adoption rising and more households investing in rooftop solar, V2H technology could soon become a mainstream tool for managing energy costs," adds Ms Azarbakhsh.
The researchers note that future studies could explore workplace and public EV charging or apply the model to high-density housing such as apartment buildings.
The research group, led by Ms Azarbakhsh, with Dr Amin Mahmoudi, Senior Lecturer in Electrical Engineering, and Professor of Electronic and Electrical Engineering Apel Mahmud at Flinders University, also led a 2025 study to measure variations in household load profiles, average daily consumption (15.6 kWh vs 21.35 kWh) and EV-related uncertainties such as arrival/departure times.
Both studies consistently show that V2H operation can reduce the need for a dedicated home battery while lowering household electricity costs.
Ms Azarbakhsh says the studies indicate the value to household budgets of using EV batteries to interact with the electricity grid.
"As Australia moves towards a cleaner energy future, V2H offers a practical, cost-effective pathway forward," she says.
'Optimal Sizing of Photovoltaic and Battery Energy Storage for Residential Houses in South Australia by Considering Vehicle-to-Home Operation' (2025) by G Azarbakhsh, A Mahmoudi, S Kahourzade, A Yazdani and A Mahmud was published in The Institution of Engineering and Technology Renewable Power Generation. DOI: 10.1049/rpg2.70053.
The followup study, 'Impact of Vehicle-to-Home Integration on Optimal Capacity of Solar Battery System for Houses' was recently presented at the Australasian Universities Power Engineering Conference (AUPEC). DOI: 10.1109/AUPEC66173/2025.11219607.
