Solar on Superstores

Big roofs, big potential for renewable energy

Big roofs, big potential for renewable energy

Photo: IKEA
Bryn Huxley-Reicher

Former Policy Analyst, Frontier Group

Wade Wilson
Ben Sonnega

A report by Environment America Research & Policy Center and Frontier Group

Solar energy is the fastest-growing form of electricity generation in the United States. America has 40 times as much solar electricity generation capacity as in 2010. That’s because the U.S. has a huge solar resource, solar power is cheap and getting cheaper quickly, and good public policies make solar power attractive for individuals and businesses.

But America has only just begun to tap its immense solar resource.


This is an average Walmart. It has 180,000 square feet of rooftop. About the size of three football fields.

That amount of rooftop space could support enough solar energy to power nearly 200 homes.

And there are lots of superstores. Our smallest state, Rhode Island, has 279.

Iowa has more than 1,000 superstores.

California has more than 10,000 superstores.

There are over 100,000 superstores in the U.S., with almost 7.2 billion square feet of rooftop. That’s the size of El Paso, Texas.

Putting solar power on all superstores could power almost 8 million homes. That’s the equivalent of powering 35 cities the size of El Paso, Texas.

It would also cut annual greenhouse gas emissions equivalent to taking more than 11.3 million gas-powered cars off the road.



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. In order to achieve a future of 100% clean and renewable energy, America must capitalize on every solar energy opportunity, 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 used by almost 8 million average U.S. homes, or more than 30,400 typical Walmart stores.

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.

  • 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 also makes the grid more resilient to outages and disruptions.

The map below shows the solar PV technical potential on big box stores in each state, as well as the reductions in global warming emissions each state would see by building out that technical potential. Hover over or click on a state to see its potential big box solar generation and greenhouse gas emissions reduction potential.





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 its installations in California were expected to provide between 20% to 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 resources needed to meet those goals. To accelerate adoption of solar energy by America’s businesses, officials at all levels of government should implement supportive policies that streamline the permitting and installation process, remove financial barriers, and allow for non-traditional financing or partnership mechanisms.


Tell Walmart to go solar
Workers doing rooftop solar installation

Clean energy

Tell Walmart to go solar

To protect our communities and the future of our planet, we must move off of fossil fuels, and businesses have a big role to play in that transition.



Bryn Huxley-Reicher

Former Policy Analyst, Frontier Group

Wade Wilson

Ben Sonnega