A new technology called Vehicle to Grid (V2G) energy transfer is currently available to consumers in Japan and later elsewhere. The technology allows a Nissan Leaf owner to power home appliances with the vehicle battery during a power outage. In addition to functioning as emergency power back up the system can help save money on regular electric bills. The consumer saves on electric bills by purchasing electricity when it is cheap in the middle of the night, storing the energy in the vehicle battery then using the stored electricity instead of electricity purchased from the power utility during the late afternoon when rates are highest. First electricity is stored in the vehicle battery at night while energy is cheap, this is just a standard charge cycle as any Leaf owner would perform. Next the energy stored in the battery is used to power the house during late afernoon when energy is most expensive. The cutting edge technology is built into the “Leaf to Home” unit which uses the energy in the vehicle battery to power the house. This must be accomplished with out damaging the vehicle battery or causing an unsafe situation where the house mains feed power to damaged power lines during an outage. The “Leaf to Home” unit most probably communicates with the vehicle computer to protect the battery from damage during discharge and controls the house main breakers to isolate the house from the grid as needed. Overall the system gives the customer the ability take advantage of a price differential creating a substantial savings and helps the electric utility avoid rolling blackouts caused by excessive peak demands on the grid.
The Japanese advertisement shown in the photos below illustrates how the system works.
Some details about the system:
Intial system cost: 567,000 Yen – $7118
Government incentive: 240,000 Yen – $3012
Total cost (uninstalled)327,000 Yen – $4104
Monthly savings on electric bills 440o yen – $55
( provided 10kWh per day are used through the system)
Green Gears has been active in V2G implementation since 2007. Green Gears was contracted by Google and PG&E to perform hands on installation of parts and equipment for V2G and PHEV demonstration and testing. These initial proof of concept demonstrations have spurred on further development and integration by Nissan and other automakers. 5 Years after the widely publicized Google/ Pg&E demonstration a consumer product is available.
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