Microsoft just announced what it calls “the single largest corporate purchase of solar energy ever in the United States,” buying 315 megawatts from two new solar projects in Virginia as part of its ongoing effort to power its global data centers with renewable energy.

The power will come from 750,000 solar panels spread across 2,000 acres at projects called Pleinmont I and II. With the purchase, the company says its total renewable energy portfolio will reach 1.2 gigawatts globally, which a Microsoft representative described as “enough power to light up 100 million LED bulbs, or send Marty McFly back to the future.”

Microsoft says it has reached its goal of powering at least 50 percent of its data centers with clean energy by this year. The company says the latest deal will help achieve its next goal, powering 60 percent of its data centers with clean energy by 2020.

Financial terms of the deal were not disclosed. It’s part of a larger trend of major U.S. companies increasingly turning to renewable energy sources.

The Virginia solar development is operated by renewable energy producer sPower, whose CEO Ryan Creamer said in a news release that Microsoft’s commitment to the project allowed it to proceed and opened the door to sell power from the rest of the 500 megawatt project to other buyers at competitive prices.

“While we’ve made a great deal of progress, we still have a long way to go,” writes Brad Smith, Microsoft president and chief legal officer, in a post tonight. “As we look toward 2020, we are exploring new models and methods for aggregation. We will continue to push the envelope on R&D, looking for new ways to improve our energy efficiency and enable our datacenters to benefit the grid. And we are more active than ever on the policy front, working in Washington, D.C., state capitals and internationally to help craft policies that enable everyone to have access to a fair, competitive market rate and improved access to clean energy.”