In Menifee, EVs Keep Homes Lit at Night

In Menifee, California, six newly built homes are testing a North American first: electric vehicles capable of powering homes using the Combined Charging System (CCS) high-power DC charging standard. Each house uses a host Kia EV9 electric vehicle connected to a Wallbox Quasar 2 bi-directional charger, allowing the car’s 100 kilowatt-hour (kWh) battery to operate essential circuits during power outages or periods of high electricity prices. It is the first residential vehicle-to-home (V2H) system in the United States that uses the Combined Charging System (CCS) standard. CCS is the charging system commonly used in European and North American residential and public charging installations.

Since July, smart electrical panels in homes automatically manage the two-way flow of energy: charging vehicles from the grid or rooftop solar, then reversing the flow of energy when needed. The system isolates each home from the grid in the event of an outage, preventing any current from flowing into external power lines and endangering nearby utility crews and equipment.

“This project demonstrates that bidirectional charging with CCS can work in occupied homes,” says Scott Samuelsen, founding director of the Advanced Power and Energy Program (APEP) at the University of California, Irvine, who is monitoring the two-year trial. “It’s a step forward toward vehicles that not only move people but also strengthen the energy system.”

Menifee means a lot

For over a decade, two-way charging has been available, but mainly limited to Japan. In 2012, Nissan’s LEAF-to-Home program proved the idea viable after the Tōhoku earthquake and tsunami, but this Nissan system relied on the CHAdeMO standard, which is little used outside of Japan. Most North American manufacturers[et européens]have instead chosen CCS, a standard that until recently only supported one-way fast DC charging.[andEuropeanmanufacturerschoseCCSinstead—astandardthatuntilrecentlysupportedonlyone-wayfastDCcharging[andEuropeanmanufacturerschoseCCSinstead—astandardthatuntilrecentlysupportedonlyone-wayfastDCcharging

This distinction makes Menifee’s V2H-enabled neighborhood noteworthy: It’s the first CCS-based V2H deployment in occupied homes, providing researchers with real-world field data on a technology that has long been trapped in pilot programs. Pairing the Kia EV9 SUV with Wallbox’s commercially available Quasar 2 can deliver up to 12 kilowatts of vehicle power to the home.

It’s a step toward vehicles that not only move people, but also strengthen the energy system.
–Scott Samuelsen, University of California, Irvine

Elsewhere, commercial V2H momentum has slowed. Ford’s F-150 Lightning supports home backup through Sunrun, but Sunrun equipment is not CCS compatible. Additionally, Ford announced a pause in production of the pickup truck, delaying its expansion. GM’s Ultium Home — a V2H system that works with the automaker’s Cadillac Lyriq, Cadillac Escalade IQ, Chevrolet Blazer, Chevrolet Equinox, Chevrolet Silverado and GMC Sierra electric vehicles — faces similar setbacks. Tesla’s PowerShare V2H feature is still stuck in early and limited commercial deployment, with two-way compatibility limited to the company’s Cybertruck. Menifee, in contrast, produces operational data on actual households.

Why CCS is important

When electric vehicles came onto the market, CCS was designed for one task: quickly transferring energy from the grid to the car. The main goal was reliable, standardized and fast charging. This fact helps explain the difference between CCS public chargers (many of which are rated at 350 kilowatts or more) and their CHAdeMO-based counterparts, which typically max out at 100 kW (but are capable of providing backup or home network services).

Bidirectional operation was not included in the original CCS standard for several reasons. Early automakers and utilities were concerned about security risks, network interference, and the added cost of hardware. So CCS’s original communications protocol connecting electric vehicles and charging stations (ISO 15118) didn’t even include an electronic handshake for energy export. The 2022 update, ISO 15118-20, added secure two-way communication, allowing CCS vehicles to deliver energy to buildings and the grid.

Wallbox’s Quasar 2 residential charger implements the update via an active bridge converter circuit constructed with silicon carbide transistors, enabling efficient bidirectional flow. Its 12 kW rating can support typical critical loads in a home, such as heating and cooling, refrigeration and networking, says Aleix Maixé Sas, electronic system architect at Wallbox.

As the company name humbly suggests, Wallbox’s chargers look like just plain old boxes, although they contain high-tech components.Wall box

The Menifee plan

Each of the Menifee homes equipped with a V2H system combines a rooftop solar panel with a 13 kWh SunVault stationary battery from SunPower. In normal operation, solar energy powers daily household loads and charges the stationary battery. On very sunny days, the solar panels can also recharge the Kia EV9’s battery. When the grid goes down or energy prices rise, the home insulates itself: solar power and energy stored in the SunVault keep essential systems and appliances running, while the EV battery extends power if the outage persists.

Last summer, UC Irvine researchers tracked how solar generation, stationary storage and vehicle power interacted under summer demand and wildfire-related grid stress. They found that “the vehicle adds major resilience functionality,” according to Samuelsen, who is the Menifee Project Manager. “This can relieve strain on the grid, increase the use of renewable energy and reduce costs by providing electricity during peak times.”

Bidirectional engineering

Home builders and electric vehicle service equipment manufacturers such as Wallbox are not the only entities reconsidering how to meet the technical requirements introduced by V2H. Utilities also need to make changes to accommodate the two-way flow of energy. Interconnection procedures and energy pricing structures are among the factors that need to be rethought or reconsidered.

A glimpse of the energy future

Analysts expect double-digit annual growth in sales of two-way charging systems through the late 2020s as costs fall and standards evolve. In regions facing wildfire or storm-related outages and steep time-of-use price curves, projects like Menifee’s are clearly leading the way in using cars as huge, flexible energy stores.

When electric vehicle batteries can deliver power to homes as easily as propulsion, the line between transportation and energy will begin to disappear, and with it, the old concepts of who is an energy supplier and who is a customer.

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