Vehicle-to-home (V2H) vs Vehicle-to-grid (V2G) Explained
With the growing trend towards renewable energy and the electrification of transportation, new opportunities for energy management are emerging. Among these, Vehicle-to-Home (V2H) and Vehicle-to-Grid (V2G) technologies are notable for their potential to revolutionize how we create, store, and use energy. As we move towards a more sustainable future, understanding these technologies and their implications is crucial.
History and Concept Development
The concepts of V2H and V2G have been around since the late 1990s and early 2000s, as academics and researchers began to explore the potential of electric vehicles (EVs) beyond transportation. The idea was simple yet revolutionary: At their core, both V2H and V2G technologies leverage the large batteries found in electric vehicles as a form of energy storage. A typical EV battery has a capacity of around 65 kWh, which is nearly five times the capacity of a typical home battery storage system like the Tesla Powerwall. This substantial storage potential makes electric vehicles an attractive option for energy management strategies. So, what if the large batteries in electric vehicles could be used not just for driving, but also for storing and supplying energy?
How does V2H and V2G work?
Vehicle-to-Home (V2H)
V2H technology allows an electric vehicle’s battery to supply power directly to a home or building. This capability can provide a significant backup power source during outages, help manage peak energy loads, and allow homeowners or property owners to make use of renewable energy they produce via solar panels or wind turbines.
Vehicle-to-Grid (V2G)
V2G technology takes the concept of V2H one step further. With V2G, electric vehicles can actually supply power back to the electric grid and reduce risk of grid failures or blackouts. This could help balance power supply and demand, reduce peak loads, and even provide a potential source of revenue for EV owners who sell their excess power back to the grid.
Other than a source of revenue, other potential advantages are:
- Balancing Supply and Demand
Peak power demand typically occurs during the day and then evening when people come home from work and school. If everyone plugs in their EV at this time, it could strain the grid significantly, leading to possible blackouts.
- Harnessing Renewable Energy Efficiently
One of the most substantial benefits of daytime charging is its synergy with renewable energy sources, particularly solar power. Since solar energy production is at its peak during daylight hours, this electricity can be directly used to charge EVs. This practice maximizes the use of renewables, reduces reliance on fossil-fuel-based power plants.
- Encouraging Smart Grid Technology
The shift to daytime charging can encourage the development and adoption of smart grid technology. Smart grids use real-time data about power supply and demand to optimize the delivery of electricity so could allow for V2G technologies, where EVs feed power back into the grid during peak demand times. With proper incentives, users can be encouraged to charge their EVs when renewable energy production is high and demand on the grid is low.
- Enhancing Grid Stability
Evenly distributed EV charging throughout the day can contribute to overall grid stability. It can also provide a more predictable load pattern, making it easier for utility companies to manage their resources effectively. This predictability can result in better service quality and fewer blackouts.
Failed Concepts and Lessons Learned
Like any new technology, V2H and V2G have had their share of setbacks. Early attempts to implement these technologies often ran into issues with battery lifespan, power output limitations, and regulatory hurdles. For instance, frequent charge and discharge cycles were found to degrade the batteries of electric vehicles faster than anticipated, limiting the viability of the technology.
Despite the potential benefits of V2H and V2G technologies, their adoption has been slowed down by several challenges. For one, the regulatory landscape has posed difficulties, with no standard protocols for bidirectional charging. Moreover, bidirectional chargers, like solar inverters, are generally considered to be a form of power generation and must meet regulatory safety and shutdown standards.
Meanwhile, regulatory changes are slowly making it easier for these technologies to be adopted on a wider scale.
One of other major concerns, which stems from the lessons leaned, is the potential impact of frequent charging and discharging on the lifespan of EV batteries. While modern batteries are getting a lot better, we can’t dismiss the pure physics/chemistry where it comes to material degradation. Moreover, based on historical information (albeit true), a lot of people have a preconception that they will, at some point, need to change the battery in their car for a new one and pay thousands for it.
Additionally, standardization is needed in terms of charging protocols and connectors. There are several at the moment and as every EV owner would testify, hauling adapters in your trunk is not great.
Lastly, the high cost of bidirectional chargers, coupled with the small number of compatible EVs, also poses a challenge to the mass adoption of V2H and V2G technologies.
However, these challenges have led to valuable lessons and advancements. Improvements in battery technology, for example, have significantly increased their lifespan and durability, making them better suited for V2H and V2G applications.
Current State of the V2H and V2G Technology
As of 2023, V2H and V2G technologies are still in their early stages of adoption. However, they are becoming increasingly common, especially in regions with high penetration of renewable energy sources and electric vehicles.
Improvements in battery technology and smart grid infrastructure, along with favorable regulatory changes, are driving the adoption of these technologies. A number of pilot projects and commercial applications have demonstrated their potential, and several car manufacturers are now offering vehicles with built-in V2H or V2G capabilities.
Which Electric Cars Have Bidirectional Charging?
Currently, only a few EV models are capable of bidirectional charging. The Nissan Leaf and Mitsubishi Outlander PHEV are among the most well-known EVs with this capability. More recently, the Ford F-150 Lightning EV introduced the ability to operate in V2H mode using a CCS connector via an in-vehicle bidirectional charger.
Other cars with bidirectional charging systems are:
- Hyundai Ioniq 5
- Kia EV6
- Hyundai Ioniq 6
- Kia EV9
- Kia Niro EV
- 2023 Fisker Ocean
- 2024 Chevrolet Silverado EV (Work Truck and Rally Sport Truck trims)
- 2023 Genesis GV70
Future Trends
Looking ahead, V2H and V2G technologies are expected to play an important role in the energy transition. As the adoption of renewable energy and electric vehicles continues to grow, so too will the demand for flexible, reliable energy storage and management solutions.
Key trends to watch for include:
- Increased adoption of V2H and V2G technologies: As more electric vehicles hit the roads and more homes and businesses install renewable energy systems, expect to see a corresponding increase in the use of V2H and V2G technologies.
- Advancements in battery technology: Continued improvements in battery technology will make V2H and V2G more viable and cost-effective. This includes not only electric vehicle batteries, but also stationary energy storage solutions.
Final thoughts
Despite some of these challenges, the benefits of V2H and V2G technologies are very compelling, and will certainly be a consideration for the future grid design in the long run. In the short term, they can provide backup power during outages, help to stabilize the grid, increase energy self-sufficiency, and even generate income for EV owners. As the number of EVs on the road continues to increase, the potential of these technologies to transform our energy systems becomes even greater.
FAQs
V2H technology allows an electric vehicle to supply power to a home or business, much like a home battery system. It can store excess solar energy and provide power to a home, and it can also serve as backup power during a blackout.
V2G technology allows electric vehicles to feed energy back into the electrical grid. By exporting stored energy to the grid during peak demand periods, V2G can help to stabilize the grid, improve energy efficiency, and even generate income for EV owners through participation in Virtual Power Plant (VPP) programs.
V2L technology allows an EV to power appliances or even charge other EVs. Unlike V2H and V2G, V2L does not require a bidirectional charger, making it a simpler technology to implement.
A bidirectional charger is an advanced EV charger capable of two-way charging – from AC (Alternating Current) to DC (Direct Current), and vice versa. These chargers are more complex and expensive than standard EV chargers due to their advanced power conversion electronics and the ability to manage the energy flow to and from the vehicle.
The major challenges include the potential impact of frequent charging and discharging on the lifespan of EV batteries, the need for standardization in terms of charging protocols and connectors, and the high cost of bidirectional chargers, coupled with the small number of compatible EVs.
These technologies can provide backup power during outages, help to stabilize the grid, increase energy self-sufficiency, and even generate income for EV owners. They have the potential to transform our energy systems as the number of EVs on the road continues to increase.
Yes, in some regions and under certain programs, EV owners can receive credits or reduced electricity costs for participating in V2G programs, effectively turning their EVs into income-generating assets.
For V2H to operate, it requires a compatible bidirectional charger and additional equipment, including an energy meter (CT meter) which must be installed at the main grid connection point. When the system detects grid energy consumed by your home, it signals the bidirectional EV charger to discharge an equal amount, thus offsetting any power drawn from the grid. When the system detects energy being exported from a rooftop solar array, it diverts this to charge the EV. In the event of a blackout or emergency, the V2H system must be able to detect the grid outage and isolate from the network using an automatic contactor (switch). This is known as islanding, and the bidirectional inverter essentially operates as an off-grid inverter using the EV battery.
This is one of the major concerns and a topic of ongoing research. Frequent charging and discharging could potentially impact the lifespan of an EV battery, although it’s not yet clear to what extent. Some studies suggest that the impact could be minimal if the charging and discharging are managed properly.
No, the availability of V2H and V2G technologies can vary greatly depending on the region and the local regulatory landscape. In addition, the infrastructure for these technologies, such as compatible EV models and bidirectional chargers, is not universally available.
No, only EVs that are compatible with bidirectional charging can utilize V2H or V2G technologies. As of now, only a few EV models have this capability, although more are expected in the future.
