Electric Vehicle Charging Comes Home

Electric Vehicle Charging Comes Home

This piece was originally published in the May 2016 issue of ei, the magazine of the electroindustry.

By Charles Botsford, P.E., Chemical Engineer, AeroVironment

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Of all the places to charge your electric vehicle (EV), your home is one of the most important. Home charging is called the 80-percent solution, which means that EV manufacturers and others estimate that 80 percent of all EV charging occurs at home. The next-most-important place to charge is where you work; public charging takes up the rest of the slack.

EV supply equipment (EVSE) comes in Level 1 (120V) and Level 2 (240V). The charger that comes in the trunk of an EV is Level 1, although that may change to a dual Level 1/Level 2 charger. A Level 1 charger is plugged into a 120V garage wall outlet. Since it will be charging at a rate of about a 1kW, it will take all night (and then some) to charge your EV.

Level 2 EVSE, on the other hand, charges much faster (typically 3 to 4 hours), depending how many miles were driven. Level 2 EVSE usually requires an electrician-installed, dedicated circuit breaker on a line that runs from the house panel to the garage. Not to worry—this is now very common for electricians and city planning departments (a permit is required). With a Level 2 EVSE, charge time can be cut by a factor of three for a 16A EVSE or a factor of five for a 30A EVSE.

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Prototype shown in home garage simulation. The pictures are residential EVSE from a California Energy Commission program, which funded the supply and installation of Level 2 EVSE.

Residential EVSE have been non-networked up until now. That means you just plug in the EV and it starts charging. It also means you don’t have access to data, charge scheduling, or tracking of electric utility rates. However, EVSE is being introduced that can track kilowatt hours used, monitor utility rates, schedule charging to get the best rate, and make sure your EV is charged in the morning when you wake up.

That you are able to monitor and potentially control how you charge your EV can enormously benefit the grid. It also enables solar and wind power generation to integrate with traditional power plants much more easily and effectively.

One new benefit coming to EV residents in California and Oregon is carbon credits through the states’ Low Carbon Fuel Standards (LCFS) programs. Driving an EV means lowering your carbon footprint. In California, the utilities take the residential credits and transfer that benefit back to the resident.

Mr. Botsford is a chemical engineer with a wide range of experience relative to electric vehicles, renewable energy systems, power electronics, oil refining, and air quality issues.



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