V2H, or vehicle-to-home, uses smart EV charging and bidirectional (two way) charging to transfer energy stored in the battery of a parked electrical vehicle (EV) to the home for use as a backup power source during outages. The battery in an EV could keep a home or small business running for several days. Homeowners living in areas where utilities offer variable pricing can use V2H to reduce their electric bills by tapping the EV battery for power during peak demand times when electricity from the grid is most costly.
Using the energy stored in your EV battery instead of grid energy can also help reduce your carbon footprint. V2H combined with home solar panels is even more planet friendly. The EV battery can store excess energy produced during the day by solar panels (home-to-vehicle power flow), and that energy can be used in the evening to power your home (vehicle-to-home power flow). In this use case, the EV is supplementing or replacing an expensive battery for home storage.
Is V2H part of V2X?
V2H is similar to V2G, or vehicle-to-grid, where stored EV electricity is transferred to the grid to balance loads during peak demand times. Other applications of bidirectional charging are V2B (vehicle-to-building) and V2L (vehicle-to-load), and all are grouped under the catch term V2X, or vehicle-to-everything. The difference is the destination for the electricity drawn from the EV battery.
All are considered emerging technologies, with pilots for V2H and V2G going on around the world. In practice, V2H, V2B, and V2L are closer to broad commercial availability than V2G because they are less technically complex. While V2H can provide significant benefit to individual consumers, V2B and V2G have the greatest potential to deliver benefits to the grid because they work on a much larger scale.
How does it work?
First off, V2H requires an electric vehicle that supports bi-directional charging, which enables the vehicle battery to receive energy and discharge energy to a destination other than the vehicle itself. Each year more EV models are hitting the road with this capability. Some EV manufacturers even offer one-stop-shop packages that include all the components needed, including solar panels.
V2H also requires:
- Smart energy management software to control the process
- A bi-directional home charger that can convert the EV battery’s DC power to the AC power needed by the home, and vice versa (these are commercially available today, but they are expensive; costs will come down when manufacturing can scale up for broad adoption)
- A communications link between the charger, the vehicle and the EV charging management platform, using the communications protocols ISO 15118 and OCPP 2.0.1
- An appropriate energy metering system
- A way to disconnect the home breaker panel from the electrical grid, a process called “islanding,” when the home is receiving power from the EV
- A connection between the bi-directional charger and the home’s entry panel, which requires installation by a licensed electrician
Will V2H degrade the EV battery?
Impact of V2H on EV battery life is an important concern. There are many factors that affect battery life, including age, temperature, state of charge during operations, ultra-fast charging, and usage (energy cycles). All batteries degrade over time, but recent research bears out earlier studies in showing that high battery use does not result in significantly higher battery degradation.
What are the benefits of V2H?
The primary benefit of V2H technology is avoiding the inconvenience of being without electricity during a blackout, whether it lasts a couple of hours or a couple of days. V2H enables you to keep your lights, critical appliances and even medical devices working without having to invest in a generator or a storage battery. V2H can also reduce energy costs, helping to offset the initial investment in the EV and the supporting V2H technology.
What are the challenges to V2H?
The primary challenges today are the limited number of EV makes and models that support bidirectional charging as well as the cost of buying and installing the associated charging and electrical system components required for V2H. As the technology becomes more mainstream, these challenges will be less significant.
