By Emily Pontecorvo for Grist.
Broadcast version by Eric Tegethoff for Washington News Service reporting for the Grist-Public News Service Collaboration

Last year, a reader wrote in to Grist's advice column with a question: Why doesn't every roof have solar panels? A report released this week by the nonprofit Environment America and the research firm Frontier Group poses a followup question: At the very least, why doesn't every big box store have rooftop solar?

The amount of space available on the rooftops of Walmarts, Targets, Home Depots, Costcos, and other large stores and shopping malls in the continental U.S. is staggering. Environment America estimates that it amounts to 7.2 billion square feet, or about the size of El Paso, Texas. Even tiny little Rhode Island has 279 stores that span at least 25,000 square feet each.

From one perspective, these shrines to consumption represent the root cause of our climate catastrophe. But there's a potential silver lining: These stores can make up for at least some of that damage by opening up their vast rooftops to solar development. At best, blanketing these stores in solar panels could reduce the need to site solar farms in rural areas where they often face opposition from neighbors and can threaten endangered species.

The report finds that superstore roofs could generate enough clean energy to power almost 8 million average U.S. homes. Or to put it another way, rooftop solar panels on big box stores could provide half of the annual electricity that these stores currently demand.

The report is a followup to a similar analysis the nonprofit conducted in 2016. In the years since, the potential power that could be generated on box store roofs increased 9 percent - not because there are so many more stores, but because solar panels have become more efficient.

In addition to reducing demand for fossil fuel energy and potentially enabling conservation elsewhere, the report points out that rooftop solar has big benefits for the stores themselves. It reduces electricity costs directly, and can also reduce heating and cooling costs by providing shade during the day and insulation at night.

Some companies have already tapped into this potential. The report identifies Ikea, Walmart, and Target as leaders in rooftop solar. Ikea has installations on 90 percent of its U.S. locations. Walmart ranks as the top retailer involved with the Environmental Protection Agency's Green Power Partnership to help businesses procure renewable energy, but the report points out that the company is involved in a lot of renewable energy development that is not on its rooftops and could redouble its efforts to generate power on its own buildings.

Environment America recommends several ways state and federal policymakers can help get this show on the road. One is to extend the federal investment tax credit for rooftop solar for 10 more years and allow companies to claim it via direct payments rather than through their tax returns. The version of the Build Back Better Act that passed in the House last fall and is currently held up in the Senate would do both. Other options include bolstering state tax credits, offering property tax exemptions for the value of the solar equipment, or exempting the equipment itself from sales taxes.

The report also encourages states to enable other business models, like allowing companies to lease the solar panels from a third party or allowing communities to invest in the projects and earn some of the benefits.

David Hughes, an environmental anthropologist at Rutgers University, has a more radical idea. When Grist spoke with him last fall, he suggested that when the owners of these large flat rooftops fail to take advantage of their solar potential, they should forfeit their rights to do so to the community or municipality. Hughes bases his argument on a law from the 1800s called the Homestead Act, under which the government offered up plots of land (stolen from Indigenous peoples) to white settlers to cultivate. But if the homesteaders failed to do anything "useful" with it within five years, the rights to the land reverted back to the government. Hughes argues that the Homestead Act could be repurposed for progressive priorities today, ensuring that when a company doesn't take advantage of the resources at its fingertips, the local community can.

"If you're Amazon - the vast majority of their warehouses are wasting sunlight. They should not have control over those roofs anymore," Hughes told me at the time. "The community or the municipality or somebody should seize it and put panels on top of it. I'm not saying seize the warehouse - I'm just saying claim the authority to climb up there and put panels on top of it!"

Carrie Baker wrote this article for Grist.

Support for this reporting was provided by Solutions Journalism Network.


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As state budget negotiations continue, groups fighting climate change are asking California lawmakers to cut subsidies for oil and gas companies rather than slash programs designed to slow global warming.

Gov. Gavin Newsom's current proposal would cut oil and gas tax breaks by $22 million this year and $17 million the following year.

Barry Vesser, COO for The Climate Center, a nonprofit advocacy group, would like to see all subsidies eliminated.

"Oil and gas companies are one of the drivers of climate change, so we should not be making their profit margins bigger by providing public subsidies, and making it harder for renewables to compete against them," Vesser argued.

Gov. Newsom has also proposed to cut funding for climate-friendly programs helping lower-income families buy an electric vehicle or switch from gas to electric appliances.

Kevin Slagle, vice president of strategic communications for the Western States Petroleum Association, said in a statement, "California's already tough business climate is pushing companies to the brink. Removing incentives will drive California straight into the arms of more expensive foreign oil, ramping up costs for everyday Californians who can least afford it."

Vesser countered the threat of higher gas prices is a red herring.

"There's a lot that goes into calculating how much the cost of gas is, and this is not even pennies on the dollar," Vesser contended.

The state Senate's early action proposal estimated the budget deficit will be between $38 billion and $53 billion. The governor is expected to release new details on his budget priorities in mid-May. The Legislature must pass a balanced budget by June 15.

The New York HEAT Act might not make the final budget.

The bill reduces the state's reliance on natural gas and cuts ratepayer costs by eliminating certain rules. It was in both legislative chambers' one-house budgets, but last-minute scrambling could remove it.

New York League of Conservation Voters Policy Director Patrick McClellan said, aside from people's preference for natural gas, other challenges have made the bill hard to pass.

"I think that there has also been some irresponsible fear-mongering against this bill from some people who oppose it," said McClellan, "basically telling people this means that their natural gas service is going to be taken away from them tomorrow, or it's going to happen without warning, and that's just not the case."

The bill would not mean gas companies could walk away from providing service to new customers, since its effects occur over a longer period.

Rural lawmakers have been skeptical about relying solely on electricity, since people could lose power in bad storms.

If the bill isn't part of the budget, McClellan said the Public Service Commission can do more to require gas utilities factor climate change into their long-term plans.

It will take more than one bill for New York State to reach its climate goals.

McClellan said developing thermal energy networks is one way to build on what the HEAT Act would do, and provide good ways to decarbonize on a larger scale instead of going house by house.

"You're able to get a larger number of buildings and people all at once," McClellan explained. "The other exciting thing about thermal energy networks is, because you are talking fundamentally about piping systems that are underground, it's an extremely similar skill set for people who already work in the fossil fuel industry."

The bill would also eliminate the Hundred Foot Rule. This requires utilities to connect new customers to a gas line for free based on their distance to an existing main gas line, typically 100 feet.

This rule allowed utilities to shift around $1 billion in costs onto about 170,000 ratepayers.

Virginia's General Assembly will consider budget amendments to reenter the Regional Greenhouse Gas Initiative, known as RGGI.

Gov. Glenn Youngkin pulled the state out of RGGI at the end of 2023, and now experts said the holes in the budget left by RGGI funding going away are not being filled. Money from the program was used to fund climate mitigation work.

Jay Ford, Virginia policy manager for the Chesapeake Bay Foundation, said the state saw many benefits when it was part of RGGI.

"We were reducing fossil fuel emissions that were being created here in Virginia," Ford pointed out. "There were some clear reductions as a result of our participation. So, we're improving air quality and we are helping expedite that transition to a clean economy."

Virginia residents mostly favored staying in RGGI, but Youngkin has said the reason for pulling out was in his view, it was a "hidden tax" for ratepayers. Ford estimated homeowners paid around $2 a month from their electric bills for RGGI and argued the trade-offs were worth it.

Between 2021 and 2023, RGGI revenue generated around $828 million for Virginia. Ford thinks not rejoining the initiative could slow down Virginia's ability to reach the Clean Economy Act's climate goals, and warned other effects could be costly to communities.

"On the ground in communities around the state, if we don't get back into RGGI, there's a real potential that the work to prepare the Commonwealth, and prepare our communities for climate impacts, could grind to a halt," Ford contended.

Virginia used RGGI money to help towns and cities fund their climate resilience plans. The state used 25-million RGGI dollars to establish a Climate Resilience Fund. There have been 107 "billion-dollar disasters" since 1980 in Virginia, with long-term costs totaling between $20 billion and $50 billion.