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Big-Box Store Roofs Have Enormous Solar-Power Potential

Walmart, Costco, Ikea, and other chains could power the equivalent of 7 million homes in the U.S.

Big-Box Store Roofs Have Enormous Solar-Power Potential

Photo: Kunal Mehta via Shutterstock

The roofs of big box retail stores are flat, vacant, and generally exposed to the sun, so they make ideal places for solar panels. Retailers have already invested heavily in solar. And now a new report shows the full potential, both for corporate savings and wider social gains.

The U.S. has 102,000 big-box stores, super-centers, and large grocery stores and malls, according to the report from Environment America and the Frontier Group. That represents about 4.5 billion feet of available roof space and a whopping 62.3 gigawatts (GW) of PV capacity. If all the stores were solarized, they could generate electricity equivalent to the needs of seven million homes.

Walmart alone, with 680 stores, has potential capacity for 5.8 GW, or enough power for 660,000 homes. Target could have enough for 233,000 homes. And Home Depot could power 200,000 homes. According to the Solar Energy Industries Association, Walmart, Costco, Kohl’s, Ikea, and Macy’s were the retailers with most solar at the end of 2015. Walmart had 142 MW and has pledged to double its solar installations by 2020.


The report says stores typically save 15%-30% of their electricity costs by installing solar, but that percentage could be higher with the addition of solar thermal units (for heating water) and energy storage, which is now coming online. Walmart, which works with SolarCity, has installed at least 11 Tesla battery systems in California already.

The average store consumes $190,000 worth of electricity bill each year. Solar panel systems could potentially offset 42% of that amount, saving retailers $8.2 billion a year. More than that, Environment America and the Frontier Group see retailers as anchor customers in the solar market, encouraging smaller companies and consumers to follow suit.

"The United States receives more than enough energy from the sun to meet the nation’s electricity needs," the report says. "Putting solar panels on big-box stores is an important step towards harnessing our solar potential and meeting the nation’s electricity demand with clean energy."

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