It’s a job that would make working as a United Nations switchboard operator seem simple. Out in Austin, Texas, the federally funded Pecan Street smart grid test bed is asking plug-in cars, rooftop solar panels, smart appliances and household batteries to talk to each other -- and to the grid at large -- in a way that allows them to shape peak loads, cut household power bills and keep the grid humming smoothly.
The project’s ambitions are lofty, to put it mildly. After all, common standards-based communications and controls are hard to come by even within the individual industry segments that make up the solar-EV-home energy mashup that Pecan Street is attempting. Getting all of these technologies to talk to one another represents an exponentially greater challenge.
No surprise, then, that the nitty-gritty details of just how all these systems will be communicating is still being worked out. But with a list of partners including General Motors, Sony, Intel, SunEdison, Whirlpool, Best Buy, Freescale and Toshiba’s Landis+Gyr, it’s likely that some of the solutions reached in the course of the project may well find their way into broader adoption.
These are the kinds of next-generation EV integration challenges that will be covered at the upcoming Greentech Media conference The Networked EV: Smart Grids and Electric Vehicles. While Pecan Street’s newest project won’t be online in time to contribute its data to this year’s conference, its inclusion of solar power should make for some interesting studies in the coming year.
Jumpstarting a Plug-In Vehicle Hot Spot
Pecan Street executive director Brewster McCracken laid out the scope of the project in a Monday interview. The latest round of the project, funded in part with a $10.5 million Department of Energy stimulus grant, will include 176 homes with about a half square-mile of solar panels. By spring 2012, most of those homes will be outfitted with home energy management systems from Sony, Intel, Whirlpool and Check-It (the latter company working with the Best Buy electronics store chain).
Next will come the EVs, courtesy of GM, which by summer 2012 will start making 102 plug-in Chevy Volts available to people living in the test area with a special offer of double the existing $7,500 federal rebate to spur purchases. Thus, this project may represent the largest concentration of plug-in vehicles that, rather than being part of a fleet (like Google’s 250 and counting plug-ins), are all under the control of individual owners.
“We’re literally throwing the car keys to 100 families and saying, 'Enjoy yourself,'” McCracken said. “We’re trying to find out how this will work in the real world.” That’s going to be a far different challenge than that posed by centrally managed fleets -- and one that's much closer to the challenge utilities are priming themselves to manage as plug-in cars start to appear in garages around the country.
“General Motors, with OnStar, has a great system for capturing all this data,” McCracken said. “But for integrating things like solar panels and batteries and home energy management systems out there, there have to be some agreed-upon protocols” in place.
The Solar-Powered, EV-Charging Home?
Developing that mix-and-match of home energy, solar power and electric vehicle charging protocols will be a major challenge. Right now, AC car charging in the U.S. is under the purview of the Society of Automotive Engineers' SAE J1722 standard, but faster DC charging remains more open, although the Japanese CHAdeMO standard is seeing a lot of uptake.
Likewise, on the home energy management front, Smart Energy Profile 2.0, which is meant to align Wi-Fi, ZigBee and HomePlug systems into a common standard, is still in the works. On the solar front, solar inverters from different vendors are using different protocols to communicate, although standards groups are hard at work on a common framework for what next-generation “smart” inverters should be able to tell the grid.
SunEdison will be in charge of developing the solar panel-connected plug-in vehicle charging systems. Just how a set of solar panels that generate energy during the day will be used to charge cars that will probably do most of their charging at night remains to be seen, though batteries could help -- at least some of the Pecan Street homes will have batteries in place, including some lithium-ion batteries being installed by Sony, McCracken said.
Also, one could imagine that solar panels generating power during late afternoon peak times could help shoulder the burden of those few cars that do remain plugged in. These are just a few of the data points that SunEdison will be collecting through the course of the project using its Energy and Environmental Data System.
Linking up solar panels and EV chargers isn’t new -- SolarCity has installed about 2,500 car-charging stations in its customers’ homes, and there’s a long list of solar-roofed car-charging parking lot projects out there, including a few by car charging startup ECOtality. But optimizing a solar power system’s output for both car charging and grid balancing represents another level of complexity.
Storing solar energy in batteries is one way to tackle the challenge of applying the sun’s energy at the times when the grid needs it most. That could come through charging and discharging EV batteries in a vehicle-to-grid arrangement -- though nothing in Pecan Street’s latest project suggests that’s part of the plan -- or it could be via home-based batteries, which are being installed in some of the Pecan Street test homes.
A Smorgasbord of Home Energy Management Options
Beyond its installation of batteries, Sony’s participation in the project is interesting for a few more reasons. First off, it’s the Japanese electronics giant’s first move into home energy management, via internet-connected set-top boxes that will give energy data and control through the television.
Secondly, it includes the intriguing promise of a device that can measure the energy usage of different household appliances from a single power distribution board -- a system that sounds a bit like technology being developed by the likes of Intel, Belkin, and startup PowerMap.
Sony hasn’t said whether or not it plans to commercialize any of its home energy management technology, so the Pecan Street project will likely be an important pilot to watch to see how the company’s system pans out. That also goes for partners such as Intel, which is taking its time rolling out its Home Energy Manager product into utility trials, and Whirlpool, which has set a 2015 date for all of its appliances to be smart grid-compatible, but which, like fellow white goods makers GE, Samsung and LG, has been slow to push them out to market.