Wal-Mart plans to use a new lighter weight and lower cost solar technology at the majority of its 20 to 30 store locations in California and Arizona that are scheduled for solar power system installations this year.
Adding about 15 megawatts of solar, the project, which will add to the 31 current solar installations Wal-Mart has in California and Hawaii, is expected to supply up to 20 to 30 percent of the total energy needs for each location, produce up to 22.5 million kilowatt hours of clean energy per year, and avoid producing more than 11,650 metric tons of carbon dioxide equivalent annually.
"This extension will help us meet our goal to become more efficient, lower our expense and help develop less traditional solar technology markets," says Mack Wyckoff, senior manager, Energy Systems Develop & Technology, at Wal-Mart, and lead on the thin-film project.
According to Wal-Mart, the thin film solar panels look similar to the traditional crystalline panels, but require fewer raw materials to manufacture, resulting in a smaller environmental impact over its life cycle.
But there are some tradeoffs. Not all of the sites will use thin-film technologies because of specific site design criteria. For example, thin-film installations, which are largely flat-mounted systems, would not be a good fit for areas where there is a significant presence of agricultural or construction with high soil disposition, says Wyckoff.
However, thin-film technology will be a good fit for development outside of California and Arizona because of their performance in non-premium sun conditions, says Wyckoff. When it's cloudy it will still produce electricity where crystalline solar requires direct sunlight, he says.
The Wal-Mart projects are using both copper indium gallium selenide (CIGS) and cadmium telluride thin film, supplied by MiaSolé and First Solar, respectively. The retailer says the large scale on-site installation of CIGS could help further the development of this technology and bring it to market quicker, while use of cadmium telluride thin film could help make the case for other businesses to adopt the technology for on-site commercial use.
SolarCity, which will design, install, own and maintain the new solar power systems on Wal-Mart locations, was selected through an RFP process led by Wal-Mart and the national environmental group, Environmental Defense Fund (EDF).
"There isn't one single technology that will best fit each of our stores so we'll have to incorporate a number of technologies. That is what this RFP exercise was really about -- identifying the best ways for us to take technologies available and use them as a best fit for each of our sites," says Wyckoff.
The project is partially financed by PG&E Corporation and National Bank ofArizona, as well as incentives from the APS Renewable Energy Incentive Program and the California Solar Initiative.
Wal-Mart is using a number of technologies to help meet its goal of being supplied by 100 percent renewable energy. For example, in the U.S., Wal-Mart purchases wind energy in Texas, and is testing fuel cells and small wind turbines. In addition, in January, Wal-Mart Stores completed three more solar projects in California, and completed its largest solar array to date with more than 5,300 solar panels at the Apple Valley distribution center in California.
In Mexico, Wal-Mart is buying energy from a local wind farm for 348 facilities and has installed solar panels on two facilities, including a store in Aguascalientes. In Canada, Wal-Mart is testing geothermal, fuel cells, solar and wind, and is the largest corporate purchaser of low-emission power through a local renewable energy provider.
By the end of this year, Wal-Mart will have solar either installed in test or roll-out mode in eight countries around the world, says Kim Saylors-Laster, Wal-Mart's vice president of energy.
