Independent information and referral site. Not a utility, contractor or government agency. Figures link to their sources. How we make money
Solar structures
Solar panels over canals in California: what has been built and what the research says
California is testing it, not yet doing it at scale. The state’s first solar-covered canals are Project Nexus, where the Turlock Irrigation District finished about 1.6 MW of panels over two canal sites in August 2025 with $20 million in state funding. A federally funded project is testing floating solar on the Delta-Mendota Canal. Covering all of the state’s canals is still a research estimate.
California Rate Relief is a referral service. We are not a licensed contractor. This page reports on public water-agency projects; figures come from the agencies and researchers named, as of the date above.
If you have not checked your roof yet, start with the California roof suitability checklist.
Key facts
- Built so far
- About 1.6 MW
- Project Nexus, two Turlock Irrigation District canal sites, done August 2025.
- TIDchecked Sep 23, 2026
- State funding
- $20 million
- From the state general fund through the Department of Water Resources.
- TIDchecked Sep 23, 2026
- Canal network studied
- 6,350 km
- About 4,000 miles of open canals, per UC Merced.
- Nature Sustainability (2021)checked Sep 23, 2026
- Pilot evaporation result
- Up to 70% less
- Shaded canals at the pilot sites, reported by UC Merced in April 2026.
- UC Mercedchecked Sep 23, 2026
Project Nexus: what has been built
The Turlock Irrigation District describes Project Nexus as “the installation of solar panel canopies over various sections of Turlock Irrigation District’s (TID) irrigation canals,” built as a proof-of-concept to study how solar over canals is designed, deployed and what else it achieves. TIDchecked Sep 23, 2026
| Where | Two sites on TID canals in Stanislaus County; UC Merced names them as Hickman and Keyes |
|---|---|
| Canal widths | Sections “ranging from 20 feet to 100 feet wide,” per TID |
| Capacity | “Over 1.6 MW,” plus 75 kW of iron-flow batteries at the narrow site |
| Built | Narrow canal by March 2025; both sites completed and commissioned by August 2025 |
| Paid for by | $20 million from the state general fund, through the California Department of Water Resources |
| Partners | TID, the Department of Water Resources, Solar AquaGrid (program manager) and UC Merced (research) |
Sources: TIDchecked Sep 23, 2026 UC Merced, April 2026checked Sep 23, 2026 The Governor’s office announced the project’s completion on April 29, 2026, describing it as a first-of-its-kind solar-covered canal in the Central Valley. The pilot is set up to measure how much electricity the panels generate, how much water they save by cutting evaporation, changes in water quality, and whether limiting vegetation growth lowers the district’s canal maintenance costs. Office of the Governorchecked Sep 23, 2026
What the pilot has shown so far
In April 2026, UC Merced reported that the shaded canals saw “up to 70 percent less evaporation and 85 percent less weed growth.” Its researchers are still monitoring energy output and evaporation with sensors at the sites, and algae growth as well. They also added a caveat worth keeping in mind: “not all canals are suitable for solar installations.” UC Mercedchecked Sep 23, 2026
Those are early findings from two short stretches of canal. Treat them as a sign the idea works where it was tried, not as a figure that scales automatically to every canal in the state.
The research behind the idea
The project grew out of a 2021 study by researchers at UC Merced and UC Santa Cruz, published in Nature Sustainability. It modeled solar panels over California’s 6,350-kilometer canal network, which the authors call the world’s largest water conveyance system, and found that covering it could cut evaporation by an average of 39,000 cubic meters per kilometer of canal a year, give or take 12,000. It also found that the financial benefits of shading the canals outweigh the extra cost of the cable-support structures needed to span them, putting the net present value of over-canal solar 20 to 50 percent above conventional ground-mounted solar. Nature Sustainability (2021)checked Sep 23, 2026
UC Merced’s summary of the same study put it in round numbers: covering about 4,000 miles of California’s canals could save 63 billion gallons of water a year and provide 13 gigawatts of solar power, with maintenance savings of as much as $40,000 per mile of canal. UC Merced, March 2021checked Sep 23, 2026
| Figure | What it is | Source |
|---|---|---|
| 63 billion gallons a year | Modeled water savings if about 4,000 miles were covered | UC Merced, 2021 |
| 13 gigawatts | Modeled solar capacity for the same coverage | UC Merced, 2021 |
| 20–50% higher net present value | Modeled, compared with conventional ground-mounted solar | Nature Sustainability, 2021 |
| About 1.6 MW | Actually built, Project Nexus | TID |
| Up to 70% less evaporation | Measured at the pilot sites | UC Merced, 2026 |
Floating solar on the Delta-Mendota Canal
A second, federally funded test takes a different approach. In April 2024, the U.S. Department of the Interior announced $15 million for the San Luis and Delta-Mendota Water Authority to “deploy potentially up to three floating solar technologies to assess the viability, costs, and benefits” on the Delta-Mendota Canal, with the Bureau of Reclamation and UC Merced as partners. U.S. Department of the Interiorchecked Sep 23, 2026 The water authority describes a five-year project in phases, from site selection and engineering through construction, operation and maintenance. SLDMWAchecked Sep 23, 2026 Floating panels sit on the water rather than on a canopy above it, which is why it is being tested separately.
What canal solar means for a California household
Canal solar is utility-scale power. Its output feeds the grid of the district or agency that owns it, the same as a solar farm, so it doesn’t change what you pay on your own bill in any way you could plan around. The choices that act on a household bill are the ones on your own property or your own account:
- Panels on your roof; start with whether your roof is ready for solar.
- A carport or patio structure when the roof won’t work; see residential solar carports in California.
- A subscription to an off-site project; see whether community solar is worth it.
- In Los Angeles, hosting a utility-owned system for a fixed payment; see leasing your roof for solar.
If you farm and have an irrigation ditch on your land, a canopy over it is a custom structure that needs engineering and permits, and if a water district owns the ditch or its right-of-way, the district decides what can be built over it. Ask the district before you ask an installer.
Frequently asked questions
Is California covering its canals with solar panels?
Only as pilots so far. Project Nexus put about 1.6 MW of panels over two Turlock Irrigation District canal sites, completed in August 2025, and a federally funded project is testing floating solar on the Delta-Mendota Canal. Covering the state’s roughly 4,000 miles of canals is a research estimate, not an adopted state plan.
Where is California’s first solar canal?
In Stanislaus County, on Turlock Irrigation District canals. UC Merced lists the pilot sites in Hickman and Keyes. The Governor’s office announced the completion of Project Nexus on April 29, 2026, calling it a first-of-its-kind solar-covered canal in the Central Valley.
How much water could solar canals save in California?
A 2021 UC Merced and UC Santa Cruz study estimated that covering about 4,000 miles of California canals could save 63 billion gallons of water a year by cutting evaporation. The peer-reviewed paper puts the average at 39,000 cubic meters per kilometer of canal each year, give or take 12,000. These are modeled estimates; the pilot is measuring real results.
Why put solar panels over canals instead of on land?
The shade cuts evaporation and weed growth, the panels use space over existing canals rather than open land, and case studies have found the cooler air next to a canal helps panels perform. The Nature Sustainability study found the financial benefits of shading outweighed the added cost of the structures needed to span canals, with a net present value 20 to 50 percent above conventional ground-mounted solar.
Will solar canals lower my electric bill?
Not in any way you can count on. Canal projects are utility-scale: their power goes into the grid of the utility or agency that owns them, like any other power plant. Your bill depends on your utility’s rates and your own usage. Rooftop solar, community solar and batteries are the options that act on a household bill.
Want to discuss your solar options?
Start with the utility on your bill and what you pay in a typical month. Contact details come after that. California Rate Relief collects the information for a solar referral; the provider confirms availability, design and price.
California Rate Relief is a referral service. We are not a licensed contractor. California Rate Relief is compensated by a solar provider when a homeowner we refer signs an agreement. How we make money
Before you send anything
- What this is
- California Rate Relief is a private referral service. It is not a contractor, does not install or finance anything, and is not a utility, a government agency or an assistance program.
- What happens after the form
- Your project details are recorded for referral to a solar provider. The provider decides whether it can help and what it can offer; availability, design and price are determined after its own review.
- How you are contacted
- Read the consent wording before submitting. Your inquiry includes contact details for follow-up about the project; a provider decides whether it can serve it.
- Using the site without submitting
- The calculators, bill comparisons and checklists on this site work without contact details, and nothing on this page requires a submission.