UC Irvine researchers are advancing technology that allows electric vehicles (EVs) to power residential homes. This system, known as vehicle-to-home (V2H) charging, enables homeowners to draw electricity directly from their car's battery to run lights, air conditioning, and appliances. The initiative aims to provide backup power during outages and reduce reliance on grid electricity during peak demand hours, typically between 4 and 10 p.m.
The Advanced Power and Energy Program (APEP) at UC Irvine has been at the forefront of V2H research for several years, working with external partners to integrate the technology into residential settings. Scott Samuelsen, founding director of APEP and professor of mechanical and aerospace engineering, leads the research, emphasizing data acquisition as crucial to understanding the EV's future role in homes.
A key impetus for V2H is the substantial energy capacity of EV batteries. Samuelsen notes that vehicle batteries are approximately eight times more energy-dense than conventional home batteries. A fully charged 100-kilowatt-hour EV battery can power a home for days, contrasting with a typical 13-kilowatt-hour home battery, which offers two to five hours of usage depending on demand. This capacity allows homeowners to potentially save up to $600 annually on utility costs by reducing electricity imports during high-rate periods, usually 4 to 9 p.m.
The project expanded into a real-world setting within the Shadow Mountain subdivision in Menifee, California. This community, built by KB Home, serves as a test bed for sustainable energy technologies. In June 2024, the UC Irvine team and Kia delivered fully electric Kia EV9 sport utility vehicles to six homeowners in the neighborhood. These participants also received Wallbox Level 2 Pulsar Plus chargers for their garages. The vehicles are provided under a lease program managed by UC Irvine, Kia Corp., and Hyundai America Technical Center Inc., with homeowners covering registration and insurance.
Roberta Howell, a 70-year-old resident of Shadow Mountain with solar panels on her home, is one such participant. She uses a Kia EV9 connected to a Wallbox V2H bidirectional electric charger. In exchange for the vehicle's use, Howell shares data from her V2H system with APEP researchers. Initial data showed Howell was not using the system as intended, prompting researchers to consider user interface design and the need for user education. After familiarization, Howell scheduled V2H to provide power from 7 to 10 every evening.
The V2H system components include a plug-in electric vehicle and bidirectional electric vehicle supply equipment (EVSE). This EVSE facilitates the two-way flow of energy: from solar panels and the utility to charge the car, and from the car to power the home when requested.
The research collaboration began in earnest in 2020 when UC Irvine engineers contacted Kia, the Hyundai America Technical Center Inc., Hyundai Motor Corp., and Wallbox to explore V2H technology. Kia’s manager of long-range strategy and planning, Steve Kosowski, stated that Kia had a prior working relationship with Professor Samuelsen and UC Irvine. This led to Kia providing an EV6 outfitted with prototype V2H software and Wallbox providing the EVSE, which were tested at the APEP Residential Laboratory on the UC Irvine campus under the direction of Samuelsen and fellow researchers Kate Forrest, Jennifer Lee, and Shan Tian. Kia's decision to proceed with V2H was made in 2021, influenced by UCI's role in bringing partners together and its work with the EV6. This work contributed to Kia's release of the V2H-ready EV9 for the 2024 model year.
Further testing with advanced EVSE prototypes and a prototype EV9 took place in the fall of 2023 at both the APEP Residential Laboratory and a KB Home model home in Menifee. In 2025, Wallbox received certification from Underwriters Laboratory for its bidirectional Quasar 2 EVSE, paving the way for commercialization. The six participating Menifee homes were equipped with these first commercial Wallbox EVSE units, necessitating an upgrade of their 50-amp charger circuits to 70 amps.
Connecting these systems to the electrical grid requires an interconnect agreement. UC Irvine began working with Southern California Edison (SCE) in early 2024 to draft such an agreement. The approval process proved lengthy, with Samuelsen noting "glaring deficiencies in the timeliness of the interconnection process." Despite this, SCE approved the "permission to operate" for the first homeowner in May of this year, with V2H services beginning at the end of that month.
Utilities are willing to participate in these innovations despite potential homeowner savings because V2H can improve grid stability, prepare for future energy demands, and help prevent rolling blackouts. Samuelsen believes California consumers will value this reliable power source, particularly when utilities temporarily shut down transmission lines to mitigate wildfire risks. Utilities also benefit by reducing the need to generate and transmit as much energy during peak evening hours or hot days with high air conditioner usage. The insights from the Menifee project are helping UC Irvine researchers and partners refine both the technology and the processes for widespread adoption.
