“I know this looks like a typical Walmart,” President Obama said, speaking from the aisles of a store in Mountain View, California. “But it’s different.”

Why? Several years ago, Walmart covered the roof of this giant California store with solar panels, and a number of big retailers such as Target and IKEA are following suit. If every U.S. supermarket and shopping center converted underused roof space to solar panels, it could generate enough clean energy to power 7 million homes.

Turning a bright idea into reality

What’s driving this change? Retailers are finding that solar is good for business.

“No one’s sitting in a Walmart board room trying to think of ways to spend more money,” said Tom Kimbis of the Solar Energy Industries Association.

With more than 5,000 stores in the United States, Walmart is the largest U.S. employer and the largest corporate producer of solar power. The company generates 142 megawatts with about 350 rooftop installations, enough to power nearly 50,000 households.

President Obama speaking at podium in large store, against backdrop of shelves of merchandise (© AP Images)
President Obama speaks at a California Walmart with a solar rooftop. (© AP Images)

Cheaper prices for solar and a wealth of roof space means that big retailers can deliver electricity at lower cost than nonrenewable fossil fuels.

This makes a big difference. Walmart estimates that 80 percent of its corporate carbon emissions are used to power its buildings. Walmart has set a goal to power its operations entirely with renewable energy.

Walmart is among 154 companies, including retailers Target, IKEA USA and Kohl’s, that took the American Businesses Act on Climate Pledge.

Rhone Resch of the Solar Energy Industries Association says this might have been a footnote in a corporate environmental report five or six years ago. But with falling prices and an abundance of rooftops perfect for solar panels, “now what you’re seeing is it’s a smart investment.”