A solar-covered, 115-foot-wide canal in Hickman, Calif. The installation is part of Project Nexus, a state-funded initiative that debuted in 2025 to better understand the viability of solar-topped canals.
California's water system is considered to be one of the most complex in the world. Thousands of miles of canals snake through Central California's agricultural fields, transporting water from the state's intricate network of dams and reservoirs to feed the thirsty almonds, strawberries and grapes (among other crops) that cover sprawling fields. Most Californians only glance at this system from a passing highway, remarking at its many miles of efficient uniformity. But soon, these waterways may start to look a little different.
Near Hickman, California, just outside Modesto, a 110-foot-wide grid of solar panels now tops a section of canal, arching over the gently flowing water. Solar projects have long been a crucial piece of the state's movement to clean energy, and these panels are part of a new project that's hoping to do far more than just generate electricity. Dubbed Project Nexus, the $20 million state-funded initiative hopes to better understand whether these installations can be an even more efficient approach to solar energy.
The waterways already irrigate much of the state's crops, but now they will also cool the solar panels, just by nature of being underneath them, increasing the panels' efficiency. Meanwhile, the panels will shade the canals, reducing evaporation and suppressing aquatic weeds. Between this installation and a 20-foot-wide section that was completed on another part of the canal in March, the project could generate a total energy output of 1.6 megawatts while producing a host of other benefits.
Jordan Harris was driving along Interstate 5 one day about a decade ago, looking at the canals traversing California's agricultural fields. Having spent much of his life in France, he wondered why California's waterways were left to bake in the inland heat, while France's canals were often tree-lined and shaded. It seemed like a natural problem to try to solve, he said, an attempt at better protecting the canals from sun and wind, especially amid drought.
As part of a new environmental project in Gujarat, India, Harris had seen canals topped with solar panels before. In 2017, he founded Solar AquaGrid and commissioned a study from UC Merced to analyze the viability of a similar initiative in California. The university projected possible outcomes if the roughly 4,000 miles of canals throughout the state were covered in solar panels. Its findings, published in the academic journal Nature Sustainability in 2021, showed that it could result in around 63 billion gallons of water savings annually. That's the equivalent of the residential water needs of more than 2 million people. Moreover, when taking into account both the power output and the benefits to the canal itself, the over-canal panels are 20% to 50% more beneficial than typical solar panels mounted on a roof or the ground.
The findings were compelling, and soon Solar AquaGrid and UC Merced teamed up with the California Department of Water Resources and the Turlock Irrigation District for the pilot. The latter is a uniquely well-positioned utility, since it both manages a section of canals and operates as the local power provider.
Facing new state mandates on clean energy production, Turlock Irrigation District spokesperson Brandon McMillan said the utility was eager to take part in the project, especially since it's cost-prohibitive to place solar arrays on local land. He said it'll take a full year before the utility can fully understand the cost benefits of placing solar panels over canals, especially when it comes to maintenance costs, but so far, the reduction in aquatic growth could be a "huge time and cost savings."
It likely would never make sense to put the panels on the entirety of the 250 miles of canals the district manages, McMillan says, but if the project is successful, it could make sense to add them in more sections of the waterways.
The country's first solar-over-canal project began producing power in 2024 near Phoenix, Arizona. The 2,700 feet of panels blanketing part of the Casa Blanca Canal benefit the Gila River Indian Community and were funded as part of President Joe Biden's Inflation Reduction Act. The next phase of the project, which adds even more panels, is already in the works.
Building on this success, as well as the strides made in India in the past 15 years, Project Nexus is also experimenting with different types of solar installation. Another section of canal, estimated for a November installation, will use a retractable system that sits much closer to the surface of the canal itself, allowing for less steel and concrete since the panels won't need to be elevated.
Harris said with each iteration, they're better understanding the costs and benefits of what the future of solar-topped canals could look like. Various factors, like which way the panels are facing or the conditions around them, could impact which technology is most effective. So far, project scientist Brandi McKuin said early estimates show that results are in line with their projections. They want to have a full year's worth of data before releasing anything official, Harris said, but "it gives us confidence that we have a good working model."
Finding dual benefits to state infrastructure, McKuin said, is going to be crucial in the future. "The challenges of climate change are going to really force us to do more with a lot less ... so this is just an example of the type of infrastructure that can make us more resilient," he said.
It may also be a chance for California to be a leader in this technology globally. Harris said he's had people interested from Romania, Ukraine, Vietnam and Spain, who all want to know more about the potential. "I think [the project] can really be symbolic of the state of California's commitment to both sustainability and innovation," Harris said.