A couple of years from now when you come home and plug your electric vehicle (EV) into a charger, there’s going to be a technology that sends the signal from the car to the charger and likely to a two-way smart meter provided by the electric utility. And chances are it’s all going to be done on a backbone that many consider uncool and low-tech: your home’s powerline.
That’s right. Your home’s high-voltage electrical lines may be the ideal network for energy efficiency services provided by a smart grid. And this is especially true if you live in a multiple dwelling unit (MDU) like a high-rise apartment building.
A couple of reasons why: First, your EV will need to send a signal to the charger and possibly the smart meter, because your car will instantly be the biggest energy draw in your home, and just a few EVs charging at once could overload a local transformer on the power grid that services several houses. Smart-charging our EVs will be essential, and the car, charger and smart meter (or other device) will all have to be in sync.
How does that involve powerline? So far, seven major auto manufacturers—GM, Ford, Audi, BMW, Porsche, Daimler and Volkswagen have thrown their support behind a communications standard called HomePlug Green Phy. It’s based on HomePlug AV that sends audio and video signals around the house over the home’s powerline, only at a much lower bit rate. Green Phy will be able to work with HomePlug AV, and be used to transmit smart grid service information from local utilities over powerline (and bridged with wireless ZigBee, which will be used in many smart meters).
The communications standard ISO/IEC 15118 (for Europe) should be completed this year and will cover communications between the electric vehicle and the charging pedestal. SAE J2931 will be the North American standard.
“We expect the first HPGP (Home Plug Green Phy)-enabled vehicles to ship before the end of next year,” says Jim Zyren, director of marketing for Green Phy chipmaker Qualcomm Atheros.
HomePlug AV has also been adopted by DLNA (Digital Living Network Alliance), the standard being used in many audio/video components like TVs for streaming media from computers and the such.
Where It’s Going
Are you getting where all this is going? It may well all go over the home’s powerline, courtesy of HomePlug AV and Green Phy. At least in theory.
Green Phy could even be used for vehicle-to-grid (V2G) applications, in which the grid can draw on power stored in multiple EV batteries.
“HomePlug Green Phy-based products support IPv6 and Smart Energy Profile 2.0 (SEP2),” says Zyren. “SEP2 includes application layer messaging necessary for support of V2G. One of the reasons the standards bodies are selecting HPGP is the fact that it can support IPv6 and has a lot of bandwidth relative to competing narrowband PLC technologies, which provides a reasonable degree of future-proofing.”
Green Phy is also being looked at to get energy information from meters in high-rise MDUs to the dwellings, which are often located too far from the meters, and the wireless signals are impeded with too much concrete for wireless technologies like ZigBee.
Green Phy has power saving features that will coordinate the Green Phy devices on the network so some can turn on only when they need to send or receive—and not miss any data. In addition, it operates at the HomePlug band to avoid noise commonly found in the home at lower frequency bands.
Qualcomm Atheros is presently in beta on its QCA7000 Green Phy chips, which should be available in May. Zyren envisions Green Phy-based light switches and smart outlets that can read energy usage and report that to other devices. He says as the technology moves forward, it will be cost-competitive with technologies like ZigBee—as well as bridged to ZigBee-communicating devices.