In September 2025, the Nexus pilot project in California, United States, was completed. The 1.6 MW solar installation is located on canals operated by the Turlock Irrigation District (TID) and was developed through a public-private partnership between the California Department of Water Resources, TID, Solar AquaGrid, and the University of California (UC), Merced. The project aimed to generate empirical data under real-world operating conditions.
Launched in 2022, the pilot evaluated the technical and operational feasibility of deploying PV systems on active irrigation canals. The concept enables dual use of existing infrastructure: clean electricity generation alongside reduced water evaporation and minimized land use – an approach particularly relevant in agricultural regions such as California’s Central Valley.
The project monitors key performance indicators including electricity generation, evaporation losses, water quality, aquatic vegetation growth, and canal maintenance requirements. After one irrigation season, initial results indicate measurable benefits for the water sector. Canal sections covered with PV modules showed reduced evaporation and lower aquatic weed proliferation, which may translate into reduced operating costs.
Specifically, continuous measurements over a full irrigation season recorded evaporation reductions of 50-70% beneath the solar arrays and an 85% decrease in algae growth, a result that could yield operational efficiencies in canal management. These findings are consistent with earlier research by UC Merced, which highlighted the potential of canal-based solar systems to improve water-use efficiency in open-channel infrastructure.
From a technical perspective, the project also serves as a testbed for multiple design configurations. These include large-span structures over wide canals, smaller systems on narrower channels, vertical installations along canal banks, and early-stage retractable prototypes. As previously reported by pv magazine, a battery energy storage system (BESS) was also deployed at the narrowest site, using 75 kW iron-flow batteries supplied by US manufacturer ESS.
This range of configurations is intended to assess system adaptability under varying hydraulic and structural conditions.
Project developers note that the scalability potential is significant, given California’s extensive canal network. A UC study estimates that covering approximately 4,000 km of canals could save 63 billion gallons of water annually, equivalent to irrigating 50,000 acres (20,234 hectares) of farmland or meeting the residential water demand of more than 2 million people. Beyond water savings, improved water quality through reduced vegetative growth is also of interest to TID.
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I’m sure installation and maintenance is a breezy also… oh, wait
What is the increased price of this design over building a conventional desert solar power plant? Then evaluate is the increased price worthwhile?
Cleaning the panels appears to be exponentially more difficult than a conventional array with long runs. (Cleaning these panels appears to be impractical!)
The structure needed to span over the canal is obviously more expensive, as of the foundations, probably on the order of 10 times more expensive per panel supported, or more! The length of each run is much, much shorter so less efficient.
Constructing this system is easily 10 times the cost of a conventional solar power plant as the logistics of laying out materials over great distances, and coordinating construction crews wood be a logistical nightmare compared with building a conventional plant in a relatively small space.
At a glance, building and maintaining this system would appear to be at least 10 times, or probably much more, than building a conventional solar power plant. It’s a nice idea at first glance. Unless it can be shown to cost equal to or 2 or 3 times the cost of a conventional plant, this idea should absolutely not be pursued with public funds!!! We need the cheapest renewable power at the cheapest price.
Also, the idea that this system blocks sunlight in any substantial way is doubtful. This design only blocks sunlight when the sun is directly overhead, which it is only very briefly in the course of the day. For all other hours of the day, the sun blasts the surface of the water just as much as it does without the cover. Anyone who has studied blocking sunlight knows how dastardly difficult it is to block light from that moving orb!