EVs and Smart Meters Seek a Common Language

For several years EV charging equipment companies have been discussing designs for enabling their products to talk with smart meters and other home energy equipment. Establishing communications pathways would enable a vehicle's energy consumption to be balanced with other home energy use and minimize the cost of electricity for transportation. Of the many wireless and wired options for these communications, interest in the ZigBee wireless protocol has grown of late.

Australian company Percepscion recently unveiled what the company is calling the first EV charger to be certified to work with the ZigBee communication standard. The ChargeIQ unit can be programmed to enable charging at specific price targets or to respond to grid signals relayed by the smart meters when the power grid is under stress. Other EV charging equipment companies including BTC Power are also developing products with ZigBee capabilities.

This communication link benefits grid operators and EV owners alike. Eventually, EV chargers in a region could slow or stop charging at times of peak demand, as part of regional demand response systems that could prevent blackouts or protect grid equipment from being overloaded

However, while getting the smart grid industry to agree on a single standard is often a challenge, corralling multiple industries is far more problematic. EV charging and automotive companies have been considering power line communications, local area networks, Wi-Fi, ZigBee, and cellular as options for vehicle to infrastructure messaging. Thanks to its use by some smart meters as well as endorsement by the Society of Automotive Engineers (SAE), ZigBee is a leading contender. Smart grid applications company Silver Spring Networks is working on integrating EV charging equipment via ZigBee, as highlighted in Pike Research's Electric Vehicle Charging Equipment report.

However, the SAE has also incorporated power line messaging between vehicles and stationary equipment into its set of charging equipment standards. Several automakers have begun work on power line communications via the HomePlug Green PHY standard, so a combination of wired and wireless communications is likely.

Startup Greenivity is looking to reduce the cost and complexity of these communications options by integrating two on a single chip. The Hybrii GV7011 chip bundles both ZigBee and HomePlug Green PHY, allowing equipment manufacturers to cover their bases.

While the communications picture is unclear today, in the end, EV drivers won't care where or how the magic happens. They'll just be happy if the grid gets a tad more stable and they can save a few pennies when they charge their vehicles.