Covering Canals with Solar PV
A pilot project to reduce evaporation and generate renewable electricity by covering irrigation canals with solar PV has completed its first phase.
In 2009, we were flying over the desert in southern California and Arizona on our way to a conference in Phoenix. From the window seat we could see below us hundreds of kilometres of open canals carrying water from the Colorado River to Phoenix. It struck us at the time that if you had asked an engineer to design a low-cost system to waste vast amounts of precious water, you could hardly come up with something more effective than putting the water in a vast network of open canals running through a hot dry desert. Also, everyone in that area faces the same challenge, along with the rest of us, of decarbonising their electricity grid.
Turlock Irrigation District in California’s Central Valley, together with University of California Merced, are implementing a solution, called Project Nexus, that addresses both of these issues in one go–installing solar photovoltaic panels (PV) over top the open canals.1 The panels reduce evaporation (therefore wastage) and they generate more renewable electricity without having to take up land that is otherwise in use. As an added benefit, the shade from the panels cools the water, which reduces weed growth in the canal, resulting in reduced maintenance costs. The District has 400 km (250 miles) of gravity fed irrigation canals and provides electrical service for 171,000 Hectares (662 square miles) of land, so the potential is large.
The installation of PV over one of the narrower canals in the District, the first phase of a pilot for Project Nexus, is complete, and the PV began delivering electricity to the grid this spring. The next phase of the pilot, over a much wider canal, is expected to be complete by the end of the year.2
The results from the pilot will inform how much of the rest of California’s 6,400 km (4,000 miles) of canal could be covered. Perhaps the project will also spur the operators of the canals supplying Phoenix to do the same.
Reading
1. TID Water & Power. “Project Nexus.” Accessed May 14, 2025. https://www.tid.org/current-projects/project-nexus/.
2. “Consortium Looks to Expand Canal Solar Projects Statewide.” Accessed May 14, 2025. https://www.turlockjournal.com/news/local/consortium-looks-to-expand-canal-solar-projects-statewide/.