Solar-panel-covered canals have their day in the sun in California (2025)

California’s Project Nexus tests whether solar canopies over irrigation canals can address three pressures at once: water loss, demand for renewable energy and competition for land. The idea gained momentum through research led by UC Merced, commissioned in 2015 by Solar AquaGrid and published in Nature Sustainability in 2021. The analysis estimated that covering California’s roughly 4,000 miles of canals could save up to 63 billion gallons of water annually - enough for about 2 million people - and generate 13 gigawatts of renewable electricity. That would equal roughly one-sixth of the state’s installed capacity. The researchers also identified potential benefits such as preserving land for conservation and reducing algae growth and canal-maintenance costs.

A $20 million state investment helped turn the research into a pilot on canals operated by the Turlock Irrigation District, a community-owned utility that provides both water and electricity. The public, private and academic partnership is now generating power and collecting data, with installations testing spans of 30 and 130 feet. Its purpose is to establish whether the projected benefits hold up in practice and what wider deployment would require, given the variation in canal sizes and conditions. The project presents canals as shared infrastructure for water and energy rather than separate systems, and California’s results are drawing attention from water and power officials internationally. The pilot is expected to be completed in 2026, with further assessment informing decisions about scaling up.