Community solar needs space to grow. Warehouse rooftops have lots of it.

Natasha Keefer is not a fan of heights. But on June 5, Keefer, who heads the Energy Solutions team for the Americas for Prologis, one of the world’s largest logistics companies, braved the ladder up to the roof of a 147,500-square-foot warehouse in Oakland, California, to take a look at the latest solar project her team had built.

The 720-kilowatt array will generate far more power than the company’s warehouse can use. In fact, the building in East Oakland is vacant right now. But that’s OK, because as a community solar project, it’s feeding electricity directly into the grid, Keefer explained to a group of state and local officials who had gathered to ​“flip the switch” on the array.

Ava Community Energy, a public energy provider serving Oakland and other East Bay and Northern California communities, will buy that power and make it available to low-income households, with a guarantee for subscribers of at least 20% savings on monthly utility bills.

Half of U.S. states and Washington, D.C., have adopted policies enabling some kind of community solar program. Many such projects are built on open fields. But as one of the country’s largest owners of logistics real estate, Prologis is ​“looking to deploy solar on as many rooftops as we can,” Keefer said.

In a sense, warehouse rooftops are like open fields in dense urban landscapes, with acres of flat space available for solar panels.

“California has a huge need for power. I’m not claiming distributed generation is the answer for all our needs,” she said. ​“But you need all the tools in your toolbox.”

How community solar can unlock solar capacity on empty roofs

Similar logic is driving U.S. states from the mid-Atlantic to the Midwest to expand opportunities for community solar on warehouses and other commercial and industrial buildings. There’s certainly a lot of roof space to go around, said Peter Light, CEO of Lumen Energy, which brokers deals between real estate owners and solar developers.

His company’s analysis of federal data indicates U.S. commercial, industrial, and institutional rooftops could host 581 gigawatts of solar, enough to provide the lower bounds of the country’s overall electricity demand. Similar data from a 2023 study by the Environment America Research and Policy Center found that warehouses across the U.S. have nearly 16.4 billion square feet of rooftop space, capable of hosting enough solar to power more than 19 million homes.

Of course, not all of that space can be used to generate solar power. But Light thinks that rooftops should be considered as valuable as open land for utilities and policymakers desperate to meet booming demand for electricity.

“With surging power prices from data centers and AI, and general electrification, utilities and states are asking, ​‘Where can we get capacity now?’” he said. In many cases, rooftop solar systems can come online more quickly than utility-scale solar, which frequently faces yearslong interconnection studies and hefty grid upgrade costs, he said.

But only a fraction of available roof space is being used for solar today. Community solar can be a ​“revolutionary” tool to unlock that rooftop potential, Light said. ​“What community solar does is turn energy complexity into rental income — and new rental income is what real estate people understand,” he said. 

Susan Uthayakumar, Prologis’ chief energy and sustainability officer, agrees that community solar is a valuable option for real estate owners.