Sun beats down on an old slag heap leftover from Pittsburgh’s industrial past in Swisshelm Park. Mountain bikers and hikers cut informal trails across parts of the mound that snake down to Nine Mile Run. But up at the top, a flat, barren expanse prepares for a transition into a 15-acre sea of solar panels.

Last week, the Urban Redevelopment Authority, which owns the property, announced it had received a $2 million grant from the EPA. It’s the last piece of a funding puzzle to clean up the site for solar. The URA had intended to develop housing there. But after struggles to clean up the toxic remains from its past life as part of a former steel manufacturing site and the challenges involved around building a required access road, the agency turned to the sun.

The URA saw an opportunity to “be a part of that transition to a cleaner energy future in the city of Pittsburgh,” according to Lilly Freedman, manager of development projects at the URA. “The site itself is really kind of perfect for solar,” Freedman said. “It’s a serendipity of sorts, because it is flat and cleared and south facing.”

Pittsburgh doesn’t have a reputation for sunshine. Clouds cover about half of Pittsburgh’s sky each year, according to data from the European Centre for Medium-Range Weather Forecasts. But solar energy isn’t that simple. As the impact of climate change accelerates, the race to decarbonize energy sources is on. The cost of solar technology has plummeted in the past decade and lucrative tax credits from the federal Inflation Reduction Act make solar an appealing investment.

Some local organizations have made the bet on solar. The University of Pittsburgh purchased all energy produced at a 20-megawatt solar site by the airport that provides 18% of the university’s power. And Pennsylvania Governor Josh Shapiro committed to using solar to power half of the government’s operations. But to catch up to the nation’s sunnier states, the region will have to blot out some persistent challenges, such as a long line to connect to the region’s power grid and a lack of storage solutions for dark hours.

“It’s pretty clear that we need to clean our energy sources,” said Aurora Sharrard, assistant vice chancellor for sustainability at the University of Pittsburgh. “Local solar power is one way to do that. With the financial incentives out there, both federally and at the state level right now, solar looks very attractive economically and environmentally.”

Here comes the sun

Solar technology works when the sun strikes a photovoltaic panel and the panel turns the sunlight into electricity. Homeowners put solar panels on their roof to capture the sunlight and power their homes and developers set up large, utility-scale solar arrays. Costs vary from about $900 a panel for a rooftop solar installation, to “tens of millions of dollars” for a 100-acre project, according to Tom Daniels, professor of city and regional planning at the Weitzman School of Design at the University of Pennsylvania.

The best indicator of a location’s solar potential is the measure of global horizontal irradiance (GHI), according to Max Zheng, professor of engineering and faculty director at Cornell Atkinson Center for Sustainability. This measures all the solar radiation — direct, diffuse, reflected — that a solar panel could receive. While Pittsburgh is a cloudy city, it is “on par” with several cities in the eastern U.S., such as Boston and Philadelphia, in terms of its solar potential from GHI, according to Zheng who looked at the average GHI between 2000 and 2020 from data from the European Centre for Medium-Range Weather Forecasts.

As far as renewables go, solar is consistent. For wind power, windy locations vary widely within a region and most places with high wind speed on land have already been developed, according to Zheng. There’s also a threshold of wind speed necessary to generate wind power. There is no threshold for the sun to produce solar energy. And the amount of GHI is fairly consistent across a region, providing “many more opportunities to develop solar farms than wind farms,” Zheng said.

And it’s cheap. Solar has the lowest levelized cost of energy in most markets in the U.S., according to a 2023 report from the Energy Technologies Area at the Berkeley Lab. “The key advance is that the cost of solar technology has come way down in the last 15 years,” Daniels said. “So that solar is now the cheapest form of electricity. It’s cheaper than coal. It’s cheaper than natural gas. And it’s even cheaper than wind.”

Another part of solar’s bargain came from the federal Inflation Reduction Act, which offers a 30% tax credit for solar installations until 2032.

Taking a chance despite challenges

The biggest challenge for solar development in southwestern Pennsylvania is the long line to get on the grid. The local operator, PJM, has a years-long backlog of projects waiting to get connected; over 90% of these projects are for renewable energy sources, according to a PJM spokesperson.

Unlike California with fields of shipping container-sized batteries to store excess solar power for use at night or on cloudy days, Pennsylvania does not have any battery storage facilities. That could change if utility-scale projects in the state start to take off, according to Daniels.

The largest solar project is Western Pennsylvania is the BE Pine 66-megawatt utility-scale array in Beaver County. The net proceeds from the solar power goes to Dollar Energy Fund, a Pittsburgh nonprofit that helps people pay their utility bills. The project became operational last December and it’s projected to bring in $75 million over 35 years, according to Chad Quinn, CEO of Dollar Energy Fund.

On top of the slag heap in Swisshelm Park, construction starts next year. The URA is waiting to find someone to purchase the energy produced. They’re watching to see if a bill legalizing community solar programs — a sort of neighborhood co-op for solar energy — passes the Pennsylvania State Senate.

“People have a perception of Pittsburgh as being too cloudy for solar,” Freedman said. “And that’s really not true. I think that’s a big misconception. We’re really hoping to show with this project — a pilot for solar on public lands — that it is possible. This is a story, to us, not just of solar development. But Pittsburgh’s transition into a green, clean city, that is no longer environmentally harming our public land.”