Superstore rooftops are ideal for solar farms, report finds

An innovative climate solution would give the US’s big-box retail stores a sustainable makeover.

A new report from Environment America and the Frontier Group calculated that the big, flat and sun-exposed roofs of superstores like Walmart and Ikea would make ideal locations for solar panels. If the 7.2 billion cumulative square feet of big-box roof space in the US were covered in solar panels, that would generate enough electricity to power nearly eight million homes.

“There’s massive potential across the entire country for big-box stores to produce solar,” report author Wade Wilson told The Washington Post. “These are big rooftops that need to be taken advantage of, and we need to start using them.”

The report relied on data from the National Renewable Energy Laboratory to calculate total roof space on the US’s more than 100,000 big-box stores. If all of this potential were used for solar panels, that could generate 84.4 terawatt-hours of energy each year.

The study authors wrote that this would have several advantages:

It would reduce greenhouse gas emissions by 52 million metric tons of carbon dioxide a year, which is the same as taking more than 11.3 million cars off the road. It would enable superstores to replace half of their yearly electricity use. It would reduce the energy lost when electricity is sent from one location to another, losses that accounted for 6% of electricity generation in 2020. It would make the electricity grid more resilient.

Some stores and locations have more potential to take advantage of this solution than others. The states that would stand to benefit the most are California, Florida, Texas, Ohio and Illinois. Meanwhile, Walmart has the greatest potential, The Washington Post reported, with nearly 784 million square feet of potential space. Target and Home Depot have the next most potential, Gizmodo reported.

Some of these stores are already taking advantage of the potential of solar energy. Walmart has installed solar panels on its California stores that provide each building with 20-30% of their electricity.

“On-site solar, including rooftop solar, is one of the many tools we use to meet our renewable energy goals,” Walmart spokesperson Mariel Messier said in a statement reported by The Washington Post.

Ikea is another leader with solar panels installed on 90% of its US locations.

However, these and other stores could still do more. The commercial sector generated 12.9 terawatt-hours of solar in 2020, which is about 15% of what the report authors said was possible from big-box stores.