California has begun implementing a project that aims to conserve billions of gallons of water each year and generate enough clean energy to power a city the size of Los Angeles for nine months annually. The initiative involves covering as much as possible of the state’s approximately 4,000 miles of irrigation canals with solar panels.
Brandi McKuin, lead researcher from the University of California, noted that many people have suggested this idea over the years. Roger Bales, a hydrologist and professor at UC Merced who helped start the project, said he has heard similar comments since the 1970s.
The appeal is clear: installing solar panels over canals could preserve land that would otherwise be used for solar farms, reduce water evaporation from canals, and produce significant amounts of renewable electricity.
After nearly ten years of research and planning, Project Nexus—a collaboration between the California Department of Water Resources, Turlock Irrigation District (TID), Solar AquaGrid, UC Merced, and UC Santa Cruz—is now operational. The project is generating both electricity and data.
A decade ago, Jordan Harris, a former music executive interested in social change initiatives like Rock the Vote and electric vehicles advocacy, teamed up with Robin Raj to form Solar AquaGrid. In 2015 they approached UC Merced to analyze whether covering canals with solar panels was feasible.
“I think we’re all highly aware of the state of emergency we’re in, with year after year of water and energy insecurity,” Harris said. “At the same time, we need to combat climate change to produce more renewable energy and decarbonize our economy. We need bold solutions today.”
UC Merced’s campus was chosen due to its involvement in systemwide initiatives on solar energy and water management. Bales assembled a team for an in-depth scientific analysis on large-scale canal-covering solar projects in California.
Their findings showed that covering all 4,000 miles of open canals could save up to 63 billion gallons of water annually—enough for two million people—and generate about 13 gigawatts of renewable power. This amount represents roughly one-sixth of California’s current installed capacity and about half the new capacity needed by 2030 to meet decarbonization targets.
Despite initial hesitation from some investors after publication in Nature Sustainability in 2021, Harris and Raj continued working with McKuin—who contributed as a Ph.D. student—to advance the project alongside colleagues at UC Santa Cruz.
“We can’t take ownership of having the idea for solar canals,” McKuin said. “What we can take ownership of is doing a robust study of the potential for California.”
India had previously implemented similar technology but faced challenges due to heavier materials and different maintenance needs compared to California’s extensive canal network serving most residents statewide.
“Had we just tried to circulate the report that we’d finished two years earlier, it would not have gotten the impact it did,” Bales said. “Being in Nature Sustainability showed that it was a peer-reviewed paper and a credible scientific result.”
State officials—including Governor Gavin Newsom’s office—supported testing these findings as part of efforts toward conserving land for biodiversity under California’s “30×30” goals (conserving 30 percent by 2030) while expanding clean energy production. The state allocated $20 million for Project Nexus’ pilot phase.
TID offered its canal infrastructure as a test site; their network supports agriculture in Stanislaus County while also providing electricity locally—a rare combination among irrigation districts.
“In 2021, we were right in the midst of a second year of a very bad drought,” Josh Weimer, TID’s director of external affairs recalled. “The paper was very timely… Up until this paper there had never been an analysis of co-benefits.”
Additional benefits identified included reduced algae growth—which lowers maintenance costs—and opportunities for direct grid support using generated power. According to Bales: “When you add together all these co-benefits… you have something with a potential payoff quite a bit greater than cost.”
McKuin added: “When I first started working on this I was skeptical it could pencil out… But when we did pencil in all these co-benefits… then we found that it could be cost-competitive with ground-mounted conventional systems.”
Project Nexus is currently collecting data from its pilot installations spanning various canal widths; ribbon-cutting events are planned next year with completion expected by 2026. International interest is high as other regions consider adopting similar approaches if successful.
Robin Raj commented: “It’s no coincidence that California is unique… And I think reaction—not just from government officials or agencies but public—is so strong because we live in critical times where action is needed quickly.”
Harris added: “We have an aging infrastructure ready to be reimagined… We can get more ‘bang for buck’ from existing utility corridors if we apply dual-use mindset.”
Raj concluded: “We’re in this exciting position to unlock innovation because we let science guide us… We wouldn’t be anywhere without University of California team.”
Plans are underway through The California Solar Canal Initiative (CSCI), involving faculty from multiple University of California campuses including Merced, Berkeley, Irvine and Law San Francisco.
