Office supply giant Staples recently completed its 37th photovoltaic installation at its headquarters in Farmingham, Mass. The company now has nearly 14 megawatts of solar across its U.S. operations. So while the company may be the biggest seller of paper it’s also among the top companies to source it’s power from green sources.

Staples partnered with SunEdison for the latest, 685 kilowatt installation on a parking lot at its headquarters. The installation consists of more than 2,440 of SunEdison’s Silvantis PV modules to help power its 650,000 square-foot headquarters office building. “This solar power system at our global headquarters is a demonstration of Staples’ dedication to sustainability across our business,” said Mark Buckley, vice president of environmental affairs for Staples. “Our partnership for solar energy with SunEdison provides cost-effective power and helps Staples meet its environmental goals.”

The company’s been sourcing power from clean energy, particularly solar, for a number of years. Since 2005 Staples said it has used more than 48 million kilowatt hours of solar across the U.S. Combined with its other renewable energy purchases, the company gets 100 percent of its electricity, more than 636 million kilowatt hours annually from renewable resources.

For its efforts, Staples has continually been among the Environmental Protection Agency’s Top 10 Green Power Partners, joining other companies like Intel, Walmart, Kohl’s and more that source part or all of their electricity from green sources. Earlier this month when the agency updated the list, Staples placed 7th in terms of overall renewable energy use for sourcing 101 percent of its electricity from green energy sources, which included wind and biogas purchases in addition to its solar generation. In terms of 100 percent green power users, the company places fourth in terms of overall green energy consumption.

By working with SunEdison on this and other solar installations, Staples is taking advantage of SunEdison’s power-purchase agreements and doesn’t have to spend any additional up-front costs for the solar arrays. “Staples has been a long-standing partner of SunEdison,” said Attila Toth, general manager distributed generation for SunEdison. For instance, the companies installed 1.5 megawatt array at its distribution center in Hagerstown, Md., in 2010. At that time it was the largest installation in Maryland and complimented another 1 megawatt system it had in the state.