California has begun implementing a project that aims to cover irrigation canals with solar panels, an idea that researchers say could save 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, known as Project Nexus, is a collaboration between the California Department of Water Resources, Turlock Irrigation District (TID), and Solar AquaGrid. The project builds on research conducted by the University of California, Merced and UC Santa Cruz. According to Brandi McKuin, the lead University of California researcher on the project, many people have considered this idea before. Roger Bales, a hydrologist and professor at UC Merced who helped launch the project, said he has been hearing “why didn’t I think of that” about solar canals since the 1970s.
The concept involves installing solar canopies over California’s approximately 4,000 miles of irrigation canals. This approach is expected to preserve valuable land for other uses while reducing water loss from evaporation and generating renewable electricity.
Jordan Harris, co-founder of Solar AquaGrid and a former music executive with experience in social change initiatives such as Rock the Vote, explained why bold solutions are needed: “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 analysis found that covering all 4,000 miles of open canals in California could save up to 63 billion gallons of water per year—enough for two million people—and potentially generate 13 gigawatts of renewable power. This amount represents roughly one-sixth of California’s current installed capacity and about half the new capacity needed to meet state decarbonization goals by 2030.
Despite initial challenges in securing investment for implementation, Harris and his colleagues continued working with UC researchers. Their findings were published in Nature Sustainability in 2021 and drew significant attention from government agencies and utility providers.
McKuin emphasized their contribution: “We can’t take ownership of having the idea for solar canals,” she said. “What we can take ownership of is doing a robust study of the potential for California.”
India had previously implemented similar projects using heavier materials mainly in rural areas. The team at UC Merced sought to adapt these ideas for use on California’s extensive canal system serving most residents statewide.
Roger Bales highlighted the importance of peer-reviewed publication: “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 notes. “Being in Nature Sustainability showed that it was a peer-reviewed paper and a credible scientific result.”
State officials allocated $20 million toward launching Project Nexus as a pilot effort after further analyses suggested additional benefits such as reduced algae growth and lower maintenance costs for irrigation districts like TID. The utility also saw opportunities to support its electrical grid directly with power generated from canal-top solar arrays.
Josh Weimer, director of external affairs at TID, noted: “In 2021, we were right in the midst of a second year of a very bad drought,” he recalled. “The paper was very timely… Up until this paper, there had never been an analysis of the co-benefits.”
Bales explained how integrating multiple benefits into infrastructure planning increases value: “When you add together all these co-benefits, then pretty soon you have something with a potential payoff quite a bit greater than the cost,” he said. “When we think about 21st-century infrastructure, we need to create multi-benefit infrastructure rather than just siloing water over here, electricity over here…”
Project Nexus is now operational at select locations along TID’s canals in Stanislaus County—testing both narrow (30-ft) and wide (130-ft) spans—with data collection underway ahead of ribbon-cutting events scheduled for next year. Completion is expected in 2026.
Brandi McKuin reflected on her evolving perspective: “When I first started working on this, I was skeptical it could pencil out,” she said. “But when we did pencil in all these co-benefits… then we found that it could be cost-competitive with a ground-mounted conventional system.”
Robin Raj, Solar AquaGrid co-founder and UC Irvine alumnus added: “It’s no coincidence that California is unique in so many ways in terms of innovation and sustainability… And I think the reaction… is so strong because we live in a critical time where we need to take action quickly.”
Harris stated: “We have an aging infrastructure ready to be reimagined. We can get more ‘bang for the buck’ from our existing utility corridors if we apply a dual-use mindset…”
Raj concluded: “We’re in this exciting position to unlock innovation because we let the science guide us… We wouldn’t be anywhere without the University of California team.”
Plans are already being developed through The California Solar Canal Initiative (CSCI), which brings together faculty from multiple University of California campuses including Merced, Berkeley, Irvine and UC Law San Francisco; more information about this consortium can be found at New multicampus consortium looks to expand solar-over-canal projects statewide.
