Big-box stores could power half of energy needs with solar, report says

America’s big-box retail and grocery stores could fulfill half of their own electricity needs and generate enough clean electricity to power more than 7.9 million U.S. homes if they covered their roofs with solar panels, a new report has found.

In addition to boosting the country’s solar energy output, such a transformation would cut greenhouse gas emissions in an amount equivalent to eliminating 11.3 million cars from the road, according to the report, published Thursday by a federation of state-based environmental advocacy organizations called Environment America.

Installing solar panels on big-box stores could also help build a more resilient electricity grid, bringing both cost savings and improved air quality, the authors explained. 

“Rooftop solar is the best electricity source for the moment we’re in. It produces inexpensive clean energy that can be used where it’s generated,” Susan Rakov, chair of Environment America Research & Policy Center’s clean energy program, said in a statement.

“Big-box store rooftops are right in the middle of most American communities, and they’re big, flat and panel-ready,” she added.

The nation’s big-box stores would collectively be able to generate 84.4 terawatt hours of solar energy, with the most potential capacity — enough to power 870,000 homes — situated in California, followed by Florida, Texas, Ohio and Illinois, the authors found. 

Comparing different retail chains, Walmart has three times as much annual rooftop solar potential as its closest competitor, Target, according to the report. The authors calculated that Walmart’s roofs could power the equivalent of 842,700 households, while Target could power 259,900 households, Home Depot 256,600, Lowe’s 223,700 and Kroger 192,500.

The U.S. has more than 100,000 such big-box stores and malls, with a cumulative total of nearly 7.2 billion square feet of rooftop space, according to the report. 

The average size of a Walmart rooftop is 180,000 square feet — equivalent to about three football fields and capable of powering nearly 200 homes, the authors noted.

“If Walmart rises to the opportunity, that will set a standard for other big-box stores to dedicate their rooftops to solar too,” Wade Wilson, an Environment America Research & Policy Center associate, said in a statement. “And the more solar on rooftops, the more potential solar in our future, as costs keep coming down and adoption goes up.”

Walmart is already among the four companies with the most solar panels installed as of 2019, the Environment America report acknowledged, citing data from the Solar Energy Industries Association. Together, Apple, Amazon, Walmart and Target had solar installations producing nearly 1.4 gigawatts that year, more than 11 percent of the country’s total solar capacity.

Walmart has already saved $1 million by integrating solar panels, with its California installations set to provide 20-30 percent of each store’s electricity needs, authors found. 

A Walmart spokeswoman told The Hill that the company aims to achieve zero emissions across its global operations by 2040, including a goal of sourcing 100 percent of its power from renewable energy by 2035.

“As of 2020, 36 percent of our global electricity needs were supplied by renewable sources,” she said, noting Walmart sources the energy both from on-site systems and from external provider purchases.

In total, she said, the company has more than 550 on-site and off-site renewable energy projects in operation or under development, with a total of more than 2.3 gigawatts of generation capacity added to the grid.

With hopes of ramping up rooftop solar installations at big-box chains, the Environment America report also recommended several public policy changes — including expanded federal clean energy tax credits, state and local tax incentives for solar, the ability to sell excess energy back to the grid, streamlined permitting and the encouragement of community solar programs. 

“To reach our clean energy goals, we need strong public policy and committed private action,” Johanna Neumann, senior director of the Campaign for 100% Renewable Energy with Environment America Research & Policy Center, said in a statement. “Big-box stores can be big leaders on the road to a clean energy future.”