The expansive rooftops of major retailers across the U.S. have the potential to generate 84.4 TWh of solar power annually, according to a recent analysis from the Environment America Research and Policy Center.
The U.S. has more than 100,000 "big-box" retail stores, supercenters, large grocery stores and malls with nearly 7.2 billion cumulative square feet of rooftop space, according to the "Solar on Superstores" report released in January. Solar panels on those rooftops could power nearly 8 million average U.S. homes and reduce global warming pollution by more than 52 million metric tons of CO2 each year, equivalent to removing more than 11.3 million passenger vehicles from roads.
Texas, California, Florida, Illinois and Ohio have the largest emissions reduction potential should big-box stores and other major retailers add solar panels to their rooftops, according to the report.
Retailers could replace half their annual electricity use by fully building out their rooftop solar potential, and producing the electricity on rooftops, closer to where it will be used, could reduce energy losses from transmission and distribution. Those big-box stores account for about 4.5% of all electricity used in the U.S., according to the report.
Apple Inc., Amazon.com Inc., Walmart Inc. and Target Corp. led all companies in solar installation as of 2019, with nearly 1.4 gigawatts of capacity, or more than 11% of the total commercial solar capacity in the U.S. that year, according to Solar Energy Industries Association statistics cited in the report. Walmart's solar installations have already saved the company more than $1 million, the report said.
The estimates of solar energy potential for large retailers in the report included only rooftop space, but the authors suggested that the stores could also install solar panels over their parking lots and on distribution warehouses.
Solar panels connected to batteries and smart inverters could also help with reliability if the larger grid is disrupted, according to the report.
Report authors recommended larger retailers consider adding solar, or expanding existing solar infrastructure, as part of climate resilience and energy efficiency plans, and that policymakers incentivize such investments with tax credits and strong net metering or similar policies.
The U.S. is expected to add 15.4 GW of new utility-scale solar power by the end of 2021, accounting for 39% of the nation's new electricity generating capacity, according to a November 2021 report from the Environment America Research and Policy Center. California has the largest market for solar power in the country, and its installed solar capacity provides almost a quarter of the state's electricity, growing from 2,635 GWh in 2011 to 48,012 GWh in 2020.
Texas is expected to experience a "solar boom" in coming years, according to the November 2021 report, and ranked second among states in overall solar power growth. The state installed 2.5 GW of solar in 2020 and is expected to add another 10 GW by 2023, driven at least in part by rapidly declining solar costs and policies incentivizing, or in some cases requiring, solar production. Texas added 9,442 GWh of solar electricity net generation from 2011 to 2020.
