Turlock district, UC Merced test solar panels on canals. State leaders get a peek
The Turlock Irrigation District was California’s first such agency when it formed in 1887. On Wednesday, it showed off another pioneering feat.
TID got a $20 million state grant in 2022 to test solar panels atop two short canal stretches. The arrays reduce evaporation of the Tuolumne River water while helping supply the district’s power customers.
A UC Merced team is assessing whether the idea is worth spreading across the 4,000 or so miles of canal in California. A detailed report is due this summer to the state Department of Water Resources.
The findings so far are promising, the scientists said at Wednesday’s gathering, which included a member of Gov. Gavin Newsom’s Cabinet and other high-ranking officials.
They met next to a solar array on the main canal, about three miles downstream of Turlock Lake. It was completed in August, in the middle of the 2025 irrigation season. The other panels were ready six months earlier, just before the season’s start, on a branch canal southwest of Keyes.
TID is the second agency in the United States to do such a solar project. The first was completed in 2024 on a Gila River canal serving Phoenix. Both were preceded by a site in Gujarat, India.
The TID effort is called Project Nexus, aligning water and energy goals. The partners include Solar AquaGrid, a Berkeley-based company.
“We have learned so much,” CEO Jordan Harris said on the canal bank Wednesday. “UC Merced researchers have been able to gather a whole irrigation season of data, and the results have been what we’ve been hoping to find.”
TID’s two sites combine for 5.7 megawatts of electricity. That is less than 1% of the peak demand of the 240,000 or so customers between south Modesto and northern Merced County. But the output could surge if adopted elsewhere on the 250 miles of canal.
TID already had plenty of climate-safe sources as of 2024. Hydropower brought 31%, mostly from Don Pedro Reservoir. Wind turbines added 21%, including what’s imported from the Pacific Northwest. Solar accounted for 6%, both local and imported. Almost all the rest came from burning natural gas, which is being phased out.
The state required utilities to get at least 33% of their power from clean sources by 2020. The mandate is 60% by 2030 and 100% by 2045.
UC Merced took first look in 2021
UC Merced’s research builds on its 2021 report on the potential for solar panels on canals. That team did not set up an actual array. Instead, it calculated sunlight intensity and other variables at eight sites between Colusa and Kern counties.
The authors concluded that solar panels on every canal could get California halfway toward it 2030 target. The evaporation savings were just 6%, but this still could help as droughts intensify in the future.
Wednesday’s program featured two researchers, Brandi McKuin and Roger Bales, who were involved in both studies. Their key points:
- The panels have not interfered with canal operation and maintenance, which was a concern raised by TID.
- The shading has reduced algae growth by 85%, meaning less canal cleaning by crews. The microbes can clog the system and affect the taste of drinking water for canals that serve cities.
- Evaporation has dropped 50% to 70% under the panels, varying with daily sunlight intensity and other factors.
- Having solar panels over canals reduces the need to install them on farmland or in deserts and other natural areas.
Just how many solar panels were installed?
The study aims to show that solar can work on waterways large and small. The Main Canal is TID’s widest at 115 feet. It got a total of 1,360 panels atop a 300-foot-long section. The other canal is just 20 feet wide. The 1,440 panels cover a 1,380-foot-long portion.
The team is still looking at the economics of bringing the idea statewide. This includes local power prices, sunlight intensity and other variables.
TID was chosen for the grant in part because it has power transmission lines along many of its canals. Its partner on the Tuolumne River, the Modesto Irrigation District, has the same setup. MID officials have said they are watching TID’s test with interest.
The 2021 study included state and federal canals with massive pumping needs that might be met with overhead solar panels. The Central Valley Project has users as far south as Kern County. The State Water Project has a parallel canal and also supplies the Los Angeles area.
“At the State Water Project, I like to say we have a front-row seat for dealing with the effects of climate change,” Deputy Director John Yarbrough said Wednesday.
‘It’s an inspirational day’ to Cabinet member
The event also drew Natural Resources Secretary Wade Crowfoot, who oversees water, energy, parks and other functions. “It’s an inspirational day,” he said. “I am inspired by the leadership of TID for having the vision and the openness for this kind of innovation.”
Crowfoot was on a different TID canal bank in 2023, watching the district spread city storm runoff onto an almond orchard. It recharged groundwater for use in drier times.
At the solar canal, Crowfoot recalled how Newsom texted him soon after the 2021 study’s release. That led to the grant to TID the next year.
The governor could not make it out to the canal Wednesday, but he commented in a day-after news release from Solar AquaGrid: “I’m proud of California for continuing to lead with innovative, outside-the-box solutions to our climate crisis — including this first-of-its-kind solar-covered canal in the Central Valley.”
