The Sono Motors Sion, an electric car with integrated solar panels that will hit the European market in the second half of 2023 at an attractive price of $25,000, is also the first electric vehicle to come to market with bi-directional charging as standard . The Sono Wallbox is capable of Vehicle-to-Grid (V2G) charging at up to 11 kilowatts of AC power (meaning no DC-to-AC inverter is required). “We want to drive the future of power generation and make bi-directional charging possible for everyone,” says Laurin Hahn, founder and CEO of Sono Motors.
V2G is the newest buzzword in the EV market. The simplified idea is that the EV battery stores energy that it can return to the grid at times of peak demand, such as mid-summer when all air conditioning is on. V2G systems ensure that the energy taken from the car is returned in time for the morning departure time chosen by the owner.
With enough vehicles connected to the grid, the environmentally damaging decision to turn on a “peak current” facility—often a dirty fossil-fuel generator that is usually mothballed—can be avoided. With 140 to 240 million electric vehicles projected to be on the road by 2030 (and perhaps a billion by 2050), an aggregate storage capacity of seven terawatt hours could be available.
A new concept is also V2X, which means Vehicle-to-Everything. These include vehicle-to-home (V2H) and vehicle-to-building (V2B). Your car can provide power to your house or apartment for several days during a power outage or can balance the electrical load of a building. V2X supplier Virta claims: “V2X transforms EV charging from electric demand control to a battery solution. It enables 10 times more efficient use of the battery compared to unidirectional smart charging.”
Sono spokesman Aaron Endré said the Sion supports both V2G and V2H. “Because Sion is effectively a solar power generator on wheels, its patented bi-directional charging function serves as a portable solar system, collecting solar energy to power appliances and other electric vehicles or flow back to private grids (V2H via the wallbox) or public grids (V2G ). Interestingly, V2G has a potential financial benefit in places where energy producers are rewarded for feeding energy back into the grid.”
Several other automakers offer bi-directional charging, although it’s usually an optional extra and is more focused on homes than utility grids. For example, the new Ford F-150 Lightning electric truck features Ford Intelligent Backup Power, a $1,310 accessory. The system is designed in such a way that the purchase of a home generator or a home battery backup system with up to 9.6 kilowatts for the household has to be avoided. The owner must also purchase Ford’s 80-amp Charging Station Pro and $3,895 Home Integration System (HIS) prior to installation. The role of HIS is to automatically disconnect the home’s power system and connect Ford Intelligent Backup Power in the event of a power outage.
Sunrun is working with Ford on these installations. When fully outfitted, with careful planning, the F-150 Lightning can power selected elements of a home for up to 10 days. Pecan Street, an energy research organization, estimates that a single plug-in EV can fully power a single family home for up to five hours, or five homes for one hour.
The Chevrolet Silverado EV will also offer bi-directional charging. GM Authority’s blog states: “Customers will also be able to export energy from their vehicle to their home during peak periods, further offsetting electricity costs, and also rely on the system to provide energy if the wider.” Power grid fails.”
Hyundai’s Electric-Global Modular Platform (E-GMP) also provides for bidirectional charging. The V2X technology has been tested in the company’s Ioniq5 in projects in Germany and the Netherlands.
Why it matters
National Renewable Energy Laboratory
V2G is important because of the way power demand ebbs and flows throughout the day. Most cars are parked for more than 95% of the day, including during working hours when heating and cooling demands and business operations are high. A study by the International Renewable Energy Agency (IRENA) found that one million electric vehicles operating in China’s Guangzhou region would reduce peak and valley charging times by 50% with V2G.
IRENA reports: “The cost reductions in generating electricity from renewable energies make electricity an attractive, low-cost fuel for the transport sector in many countries. A significant expansion in the deployment of electric vehicles also represents an opportunity for the energy sector. EV fleets can create enormous electricity storage capacities. They can act as flexible loads and distributed storage resources, providing additional flexibility to support power system operation. With smart charging, EVs could adjust their charging patterns to smooth out peak loads, fill in troughs, and support real-time grid balancing by adjusting their charge levels. Using EVs as a flexibility resource through smart charging approaches would reduce the need to invest in flexible but carbon-intensive fossil fuel power plants to offset renewable energy.”
A key issue is that existing systems are able to store renewable energy production as soon as it arrives, but storage capacity is quickly being maximized. Potential energy absorption is lost. The network of connected EV batteries greatly expands the ability to intercept and store energy. V2G is also able to reduce both energy costs and price volatility due to rapidly changing supply and demand. One study showed that a single V2G charger could save the installer up to $1,900 in electricity bills over the course of a year.
It may still be a while before electric vehicles are equipped with bidirectional charging as standard. PV Magazine reported last year, “The industry is still largely in the pilot and commercial testing phase, with significant challenges ahead before large-scale deployment can occur. While some of these obstacles – such as Licensing difficulties and lack of bi-directional support for charging protocols – overcome in due course, others may be more difficult for the industry.”
Clean Energy Reviews reports: “Part of the problem with V2G technology is the regulatory challenges and lack of standard bi-directional EV charging protocols and connector types. Some vehicle manufacturers such as Ford have developed bi-directional chargers that only work with Ford electric vehicles. Others, like Nissan, work with universal bi-directional chargers like the Wallbox Quasar…. Currently the only electric vehicle using a CCS connector [standard in the U.S.] for bi-directional charging is the Ford F-150 Lightning. However, more EVs with CCS connection ports with V2H and V2G capability will be available in the near future [Volkswagen] The announcement of its ID electric cars could offer bi-directional charging later in 2022.
Ford Motor Company
The National Renewable Energy Lab (NREL) is studying the impact of 200-kilowatt fast charging on the power grid. “The ability to address challenges for local grid infrastructure as well as vehicle-based charging facilities is critical,” said NREL.
Another headwind is that consumers may not have sufficient incentives, at least initially. Although thousands of EVs collectively represent a major asset to the power grid, the individual EV owner is unlikely to generate significant revenue from the electricity he or she passes on to the utility. To make the V2G proposition attractive, a coalition of automotive OEMs, battery suppliers, government officials and utilities would likely need to come together to create attractive incentives.
Another issue is that of battery drain. Do the repeated discharge and charge cycles of a V2G connection shorten battery life? A study in the Journal of Power Sources concluded: “Over the lifetime of a vehicle, our results show that battery degradation is indeed increased when vehicles offer V2G network services. However, the increased wear and tear from V2G is trivial compared to naturally occurring battery wear (i.e., from driving and calendar aging) if V2G services are only offered on days of greatest network demand (20 days per year in our study).”
This study was ultimately encouraging. When frequency modulation and peak shaving V2G network services are offered two hours a day, “battery degradation remains minimal, even if this network service is offered daily throughout the vehicle lifetime. Our results suggest that there is an attractive trade-off that allows vehicles to offer network services on the days when the network is most valuable, with minimal impact on vehicle battery life.”
Another study from the University of Warwick in England concluded that battery life could actually be extended by V2G. “Extensive modeling results show that when a daily driving cycle consumes between 21% and 38% of the state of charge, discharging 40% to 80% of the batteries’ state of charge to the grid can minimize the capacity drop by about 6% and the performance drop by 3% over a three-month period.” A case study using V2G in a Warwick University office building found a 9.1 percent reduction in EV battery pack capacity loss and a 12.1 percent reduction in performance degradation.
Charged EVs magazine reviewed these 2017 findings and concluded: “Currently, V2G is viewed as a service to the electric grid that utilities would pay EV owners to provide. But if it were possible to extend the life of a battery by massaging it with just the right smart charging algorithm, payments could flow the other way.” That seems a long way off, however. The only thing we know for sure about V2G is that it is coming and that it could be a major boon for a grid challenged by the rapid rollout of many EVs that need to be charged.