California has started implementing a new approach to address water conservation and clean energy production by installing solar canopies over its extensive network of irrigation canals. The initiative, known as Project Nexus, is the result of collaboration between the California Department of Water Resources, Turlock Irrigation District, Solar AquaGrid, and researchers from the University of California system, particularly UC Merced and UC Santa Cruz.
The project aims to cover portions of California’s approximately 4,000 miles of irrigation canals with solar panels. This dual-use strategy is designed to reduce water loss from evaporation and generate renewable electricity without requiring additional land. According to research led by Brandi McKuin at UC Merced, placing solar panels over all state canals could save up to 63 billion gallons of water each year—enough for 2 million people—and produce about 13 gigawatts of renewable power. That amount equals roughly one-sixth of California’s current installed capacity and about half the new capacity needed to meet the state’s 2030 decarbonization goals.
Jordan Harris, co-founder of Solar AquaGrid and initiator of the partnership with UC Merced in 2015, said: “I think we’re all highly aware of the state of emergency we’re in, with year after year of water and energy insecurity. At the same time, we need to combat climate change to produce more renewable energy and decarbonize our economy. We need bold solutions today.”
The concept has been discussed for decades but had not moved forward until recent scientific studies confirmed its benefits. Roger Bales, a hydrologist and engineering professor at UC Merced who helped launch Project Nexus, noted: “Had we just tried to circulate the report that we’d finished two years earlier, it would not have gotten the impact it did. Being in Nature Sustainability showed that it was a peer-reviewed paper and a credible scientific result.”
In addition to saving water and producing energy, covering canals with solar panels may reduce algae growth and lower maintenance costs for irrigation districts like Turlock Irrigation District (TID). Josh Weimer from TID recalled: “The paper was very timely, describing how we could save 63 billion gallons of water [and] create 13 gigawatts of renewable power if we covered all 4,000 canals. Up until this paper, there had never been an analysis of the co-benefits.”
State officials allocated $20 million for a pilot project after reviewing these findings. The pilot is testing various spans of solar panel coverage on TID’s canal system in Stanislaus County—a region known for agricultural production—as well as collecting data on efficiency and scalability.
Brandi McKuin commented on her experience with the study: “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, and did a broader systems analysis, then we found that it could be cost-competitive with a ground-mounted conventional system. It was a surprise to me.” She added: “It opened my eyes to the value of doing multi-benefit analysis because we need more of that for ecosystems, especially as we face the grand challenge of climate change.”
Project Nexus will continue gathering data through its pilot phase into 2026. Officials worldwide are monitoring its progress as they consider similar solutions elsewhere.
Robin Raj from Solar AquaGrid stated: “It’s no coincidence that California is unique in so many ways in terms of innovation and sustainability…the reaction…to this idea is so strong because we live in a critical time where we need to take action quickly.”
Harris further emphasized public readiness for such changes: “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 to generate energy on site to efficiently move water across the state.”
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.”
Expansion plans are underway through The California Solar Canal Initiative (CSCI), which involves faculty from several University of California campuses including UC Merced, UC Berkeley, UC Irvine and UC Law San Francisco.
Read more about The California Solar Canal Initiative (CSCI), which includes faculty from multiple University of California campuses including UC Merced: New multicampus consortium looks to expand solar-over-canal projects statewide.
