Solar on Superstores

Big roofs, big potential for renewable energy
Released by: Environment North Carolina Research and Policy Center

Solar energy is the fastest growing form of electricity generation in the U.S.; in fact, solar capacity has increased about 40-fold between 2010 and 2021. That growth is due to solar energy’s low and rapidly dropping price, the immensity of America’s solar resource, and public policies that make solar power a viable and economically attractive option for individuals and businesses. 

America has only just begun to tap its solar potential. The United States has the technical potential to produce 78 times as much electricity as it used in 2020 just with solar photovoltaic (PV) energy. To accelerate the transition to a future of 100% clean and renewable energy, America must take advantage of untapped solar energy opportunities, including on the rooftops of “big box” superstores.

The flat, open, sunny roofs of giant grocery stores, retail stores and shopping malls are perfect locations for solar panels. The United States has more than 100,000 big box retail stores, supercenters, large grocery stores and malls, with almost 7.2 billion cumulative square feet of rooftop space.

The rooftops of America’s big box stores and shopping centers have the potential to generate 84.4 terawatt-hours (TWh) of solar electricity each year, equivalent to the amount of electricity that would power almost 8 million average U.S. homes, or more than 30,400 typical Walmart stores. California, Florida, Texas, Ohio and Illinois have the largest big box solar generation potential. (See Appendix for state breakdowns.)

Figure ES-1: Big box store solar PV technical generation potential, by state (GWh)

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Putting solar panels on the nation’s superstores would be good for businesses, good for electricity customers, good for the grid and good for the environment.

  • Generating the full 84.4 TWh of clean solar power potential from America’s superstores would reduce global warming pollution by more than 52 million metric tons of CO2 annually – equivalent to taking over 11.3 million passenger vehicles off the road.

  • Texas, California, Florida, Illinois and Ohio have the largest emissions reduction potential. (See Appendix for state breakdowns.)

Figure ES-2: Annual carbon dioxide emissions averted by maximizing technical potential of big box rooftop solar, by state (thousand metric tons CO2)

  • Big box stores and shopping centers could replace half of their annual electricity use by fully building out their rooftop solar potential.

  • Producing electricity on rooftops, close to where the electricity will be used, reduces energy losses that happen during electricity transmission and distribution – losses that made up 6% of gross electricity generation in 2020. Solar power reduces the price volatility of electricity and makes the grid more resilient to outages and disruptions.

Many big box retail stores are already reaping the benefits of installing solar power on their rooftops. 

  • According to the Solar Energy Industries Association, the four companies with the most solar installed as of 2019 – Apple, Amazon, Walmart and Target – had solar installations totaling almost 1.4 gigawatts of capacity in that year. That’s more than 11% of the total commercial solar capacity installed in the U.S. as of 2019.

  • Walmart’s solar installations have already saved the company over $1 million, and the company’s installations in California were expected to provide between 20%-30% of each location’s electricity needs.

To combat climate change, help their communities, increase resilience and reduce energy expenses, businesses should set ambitious goals to install solar generation capacity on their facilities and invest the time and resources needed to meet those goals. They should additionally:

  • Investigate, catalog and report climate impact and energy use throughout their businesses;

  • Set strong, detailed and comprehensive environmental goals; and

  • Use their political influence to advocate for positive policy change. 

Officials at all levels of government should implement solar-friendly policies that help to accelerate adoption of solar energy by America’s businesses. These include:

  • Extending the federal investment tax credit for solar power, as well as other tax incentives and credits;

  • Ensuring that businesses that generate solar electricity are adequately compensated for the benefits they deliver to the environment, public health and consumers through programs like net metering, feed-in tariffs and value-of-solar payments;

  • Enabling and enacting financing tools like third-party and commercial Property-Assessed Clean Energy (C-PACE) financing of solar installations to help remove financial barriers to solar adoption;

  • Supporting community solar power programs to allow businesses to go solar in partnership with their communities;

  • Streamlining solar permitting and interconnection processes to make going solar easier and faster; and

  • Adopting solar-friendly rate structures that encourage businesses to go solar.