As solar energy rapidly is becoming the world's largest renewable power source, new research from McGill University offers a clearer picture of how much land that growth could require and how smarter choices could mitigate solar energy's land footprint.
"Solar photovoltaics are poised to become the largest renewable energy source globally by 2029, but both data and methods are lacking to understand the consequences of large scale growth to land," said Sarah Marie Jordaan, Associate Professor in McGill's Department of Civil Engineering jointly appointed at the Trottier Institute for Sustainability in Engineering and Design (TISED) and the Department of Civil Engineering, and Director of the Energy Technology and Policy Assessment (ETAPA) research group.
Two companion studies from Jordaan's lab fill that gap, addressing regional and global questions about how solar power can expand while minimizing pressure on land, a finite and often overlooked resource.
In the first, published in Communications Earth & Environment, the team used artificial intelligence to measure the land footprint of large solar installations across the western United States.
"We applied computer vision using deep learning techniques to high resolution aerial images to quantify the land requirements of 719 solar photovoltaic projects in the western United States," Jordaan said.
The study establishes a consistent, replicable way to measure how much land large solar projects use, creating a benchmark for understanding the land implications of rapid solar growth. It also highlights how engineering choices and location influence land efficiency, with sunnier regions and more compact designs requiring less land per unit of electricity generated.
A second study, published in Joule, scales that analysis up to a global level. Drawing on satellite-based mapping of nearly 69,000 solar installations across 65 countries, the researchers compared land use and costs between rooftop systems and large, ground-mounted solar plants.
"This study delivers a much-needed, comprehensive evaluation of global solar-land relationships and their techno-economic implications," Jordaan said.
The global analysis shows that rooftop solar offers significant land-sparing potential. It also reveals that the cost gap between rooftop and ground-mounted systems varies widely by region, shaping where rooftop deployment is most practical. Even with ground-mounted systems, land availability may not be as much of a constraint for many locations as what is often assumed.
"Solar projects can result in substantial environmental impacts locally, but our results found that reaching net-zero emissions with high growth in solar requires a negligible amount of land globally," Jordaan said. "There are substantial differences in costs and regional land availability, where targeted, region-specific policy design can support land-sparing options like rooftop solar."
About the studies
"Quantifying land-use metrics for solar photovoltaic projects in the western United States," by Sarah Marie Jordaan et al., was published in Communications Earth & Environment.
"Global land and solar energy relationships for sustainability," was published in Joule. Both studies are products of Jordaan's lab and involve collaborators from institutions in North America, Europe and Asia. This research was supported by the Alfred P. Sloan Foundation and the Natural Sciences and Engineering Research Council (NSERC) of Canada.
