Placing solar panels over canals is attracting attention in California. Proponents hope such projects will use existing infrastructure to generate renewable energy while reducing water loss from evaporation. But will solar canals live up to the hype—and will they work in California? We spoke with Turlock Irrigation District’s general manager, Michelle Reimers, about Project Nexus, a new pilot project that could help answer some of these questions.

Tell us about Turlock Irrigation District’s solar canals pilot project. Why is this a novel approach to take?

Turlock Irrigation District aims to supply our customers with 60% renewable energy by 2030 and 100% greenhouse-gas-free energy by 2045. But there are challenges: producing 1 megawatt (MW) of solar takes about 5 acres of land. One of our gas-fired power plants supplies 250 MW of electricity. You can do the math: it takes a lot of prime agricultural land to construct utility-scale solar. So we took a step back and asked if there was another way we could utilize existing assets to achieve more for our customers.

UC Merced has been studying solar-over-canal projects in different countries, so I contacted their researchers and let them know we’d be interested in a pilot project. The California Department of Water Resources (DWR) offered $20 million of funding to construct the pilot, so we created a public-private-academic partnership.

What are you learning—or what do you expect to learn—from the pilot?

For the pilot, we picked two different canal sites, 100 feet wide and 20 feet wide, which together are about 2 miles long. There will be different engineering on each site; we’ll see which performs best.

First, we’re interested in the possibility of reducing evaporation within the canal system.

Second, we have very hot summers in the valley, and there’s a lot of aquatic weed growth in the canals. This is a problem since the canals are gravity-fed—weed growth blocks the gates and can cause serious damage. It’s labor-intensive and expensive to clean the canals: we spend a million dollars on cleanup every year. We could potentially save a lot of money if solar arrays can shade the canals and reduce weed growth.

Third, we needed to be sure we could access the canals to service them and the electrical poles that run along them. Producing renewable energy on infrastructure we already own could offer real value to our customers, while possibly providing other co-benefits. And there are no interconnection fees because we’re also the electricity provider.

So we’re looking at generating solar power, reducing weed growth and evaporation, and evaluating wear and tear on the system. And we’ll be looking at scalability—if these pilot projects work, could they be deployed more widely, and be part of our pathway to meet the state’s climate goals?

What hurdles do you expect to face, and when will you know whether the pilot worked?

We faced some hurdles internally. My construction and maintenance manager’s first response to the pilot idea was, “What?” But the philosophy here is changing: we’re resetting to a “Why not?” mindset. I just ask that before we decide, let’s see how it could work. That’s when people’s creative juices start flowing. Now the staff is really excited about it; they really want to prove the concept. There’s a lot of support among employees because they were part of the planning process.

We hope to have the pilot fully functional by the middle of 2024. UC Merced will study it for a full year, and we’ll be working with them to study it from March to the end of October—a full irrigation season—to see if we run into any hiccups.

Final thoughts?

It’s an exciting time. We’re hoping for additional grant funding to put floating solar on our regulating reservoirs. The city of Healdsburg’s wastewater facilities have floating solar on their ponds. Floating solar actually produces more energy than ground-mount solar—due to more panels installed in the same square footage. And we don’t have any battery storage within our system right now; we are also piloting that at the site and integrating it into the grid.

We’re also looking at developing an education center near Project Nexus, because the valley doesn’t have a lot of off-campus places for schoolkids to go to and learn. This site could teach about solar power and water efficiency at one site. That’s why we call it “Project Nexus”—because we’re integrating electrical and water issues.