Toyota has followed Nissan with the announcement of a vehicle-to-home (V2H) system that can supply electricity from the car battery to a residence for backup or peak power, according to a story from the Green Car Congress. The program will start testing at the end of this year with about 10 households that will have Prius plug-in hybrid vehicles. An onboard inverter converts stored power into AC for home use.

The idea is to store low-cost, off-peak electricity in the vehicle’s battery and for use by the home during peak consumption times. The power flow is controlled via communication between vehicle, charging stand and a home energy management (HEM) system. The HEM system would need some kind of schedule or signal from the utility to know when to charge and when to send power back.

Nissan had previously announced a similar V2H system for its Leaf electric vehicle.

Until now, most of the press has been about the vehicle-to-grid (V2G) concept. At Smart Grid News, we have long expressed skepticism about the future prospects of V2G, which would require a special outlet or connection to allow power to flow back into the grid. V2H offers virtually the same benefits to grid stability, but without the extra connection expense.

Both V2G and V2H will shorten the life of the vehicle battery by charging and discharging it more often. For this reason, it is likely to appear first (and perhaps only) in regions with high-cost power or acute power shortages. The idea is being tested in Japan because of that country’s electricity shortfalls caused by the decommissioning of its nuclear reactors.