solar covered canals

Are Solar Covered Canals California’s Best Solution to Drought?

Installing solar panels over California’s canals 1a – Credit Dr. Brandi McKuin

Across the globe, drought has become one of the most prevalent and critical issues of our times. In the western US, it’s a growing disaster – with California’s 37.1 million people, the largest state population in the country, facing severe drought conditions. In 2022, fifty-eight California counties were given USDA disaster designations.

There is no easy fix, no simple go-to that will ease concerns about having enough water. Gone are the days where simple conservation by residents would help ease the burden on reservoirs until the annual rainy season comes. These days, the rains are more sparse and less frequent causing reservoirs to have dropped drastically, threatening hydroelectric processes.

Looking to the polestar for innovation, that’s where California is seeking solutions to this grave problem. Thus we see the marriage of solar power and waterways taking place in solar covered canals.

Four thousand miles of open canals meander through the Golden State. With a commitment to generating 50% of its electricity from renewable sources by 2030, and to generating 100% fossil free energy and being carbon neutral by 2045, California wants to transform its canal system into an electricity producing network.

There are two sides to every coin and a solar covered canal project is no exception. This is first of a short series on this subject. In this article we’ll examine the exciting potential benefits and some cautions as well. In Part 2 we’ll examine the “other side” – the negative or downside of what this innovation can create. Downside doesn’t mean this exciting innovation shouldn’t happen. But it’s important to see both sides when looking at something as important and impactful as solar canals.

Project Nexus – the pilot program determined to serve as a proof-of-concept to demonstrate and allow for further study of solar in regards to canal design, deployment and its benefits – will utilize Turlock Irrigation District’s (TID) infrastructure and electrical grid access. The Project’s $20 million funding comes from the California Department of Water Resources.

Project Nexus hasn’t begun construction yet. They’re currently building the models to study once they do. They anticipate breaking ground sometime during the first quarter of 2023. The pilot will be in two locations in California’s San Joaquin Valley –  in Hickman, east of Modesto and a mile-long canal span near the city of Ceres, California. It’s anticipated to be complete sometime in 2024.

Employing a lightweight cable suspension design, plans call for a total of 8,500 feet (2,591km) of solar panels to be built over three sections of the Turlock Irrigation District’s canals. Because California canals wind around and aren’t standard in size or height (some go uphill and/or downhill to meet a connecting canal), canal sections range in width from 20 to 100 feet (6 to 30.5 km). 

Solar Canal Structure 2 – Credit: GERMI Report

The idea of solar covered canals isn’t new. It’s been around for close to 30 years. The late Carl L. Weidert III, a Northern California biologist, spent years pursuing California governors, CALFED (a department within the California government administered under the California Resources Agency), the California State Assembly’s Energy Committee and California State Assemblyman Brian Dahle to rally around the idea of utilizing California’s canals as solar arrays to generate electricity. Of the five governors he proposed his innovative plan to over the course of approximately 25 years, only Governor Schwarzenegger responded favorably.

Weidert estimated the project’s water savings would range from 29 to 49%, saving millions of acre feet of water. A forward thinking man with insight, Weidert’s idea evolved into creating a statewide innovation design contest for colleges and universities. Sadly, because state legislation to appropriate contest prize monies was required, nothing came of this and the idea was shelved.

In 2012, India took up the baton. Gujarat, a state in western India, established the Canal Solar Power Project. SunEdison India commissioned an initial 1 MW canal top solar plant near Mehsana, 45 kms (approximately 23 miles) from Ahmedabad, Gujarat, India. The pilot project on the Narmada River was developed at a cost of $21 million million (₹ 9.68 Cr.) per MW. It used 750 meters (less than a half mile) of canal length. In the next phase, the state added a 10 MW canal top solar project in Vadodara, Gujarat at a cost of $1.2 million (₹ 9.68 Cr.) per MW. With support of the Gujarat Energy Research and Management Institute (GERMI), Jharkhand (India) planned to develop a 2 MW pilot project to generate power. 

Unfortunately, due to various circumstances (including the pandemic), as of 2022 the pilot project has not been completed.

Other states of India are actively working on exploiting their canal networks for development of canal top solar plants.

Brandi McKuin, PhD, University of California Merced project scientist and environmental engineer, heard about the solar canal project while she was working for SunEdison in India, although she never saw the installation.

She said, “the founders of what is now Solar AquaGrid approached U.C. Merced in 2021 about the concept of solar over canals and asked us to do a technical analysis of the potential”. The idea had underwriting from NRG Energy and development support from Bay Area agency, Citizen Group.

After writing and then reworking the analysis with updated cost data, McKuin submitted her white paper in 2021. This was the basis for Project Nexus.

A feasibility study published in March 2021 in the journal Nature Sustainability found, if applied statewide, the solar panels would save 63 billion gallons of water from evaporating each year. Those numbers work out to an 82% water savings. While definitely intriguing, those figures may be on the high side and they’re based on if the pilot project were to be expanded to cover ALL of California’s canals, not just the short stretches for the pilot.

Another encouraging statistic: if solar panels were deployed throughout California’s open canals, they would provide up to 13 gigawatts of renewable power annually, about half of the capacity the state needs to meet its decarbonization goals by the year 2030. Again, intriguing – if the pilot expands.

To understand the potential and realities of this project, I reached out to someone who’d been involved in the original solar canal project. Nilesh Kumar – an Energy Expert with Research Triangle International (RTI), USA- was the Executive Team Leader and Renewable Energy Expert with Jharkhand Renewable Energy Development Agency’s Project Management Unit, Government of Jharkhand and Senior Project Officer, Gujarat Energy Research and Management Institute (GERMI), Government of Gujarat, India.

Actively involved with the pilot program in India, Kumar says the main concern of this kind of project is the high cost of the solar power plant due to heavy module mounting structure on the canal top, “The cost per megawatt is double that of ground-based solar,” he said. But in regards to the cost of canal-based solar, the folks at Project Nexus say the India project was a decade ago and more importantly, they expect to use about 50 percent fewer materials. So they anticipate the costs to be more financially viable.

Kumar shared some remarkable results seen from the India canal project. The energy generation produced has increased by 2.5% due to natural cooling of the solar PV modules (with an average 10 degree C reduction in water temperature) due to evaporation of the canal water beneath the panels.

“This ultimately facilitates the shelf-life of the solar panels,” said Kumar. That’s versus the land effect of land-based solar arrays where the heat degrades the panels. Power generation is also affected by the heat.

Through assessment and statistical projection, the solar panels on the canals will remain at 90% effectiveness for over 20 years. To put this in perspective, 1,000 KW ground-based solar installation loses 2.5% capacity in 1 year, meaning it loses 80% of its capacity in 25 years. A canal-based 1,000 KW solar panel, however, loses 0.5% of its capacity in 3 years. That means a 1,000 KW canal top solar plant would remain at 80% capacity at 43 years! 

That’s a BIG savings!

Project Nexus rendering 2a – Credit: Solar Aquagrid

Solar covered canals present some other exciting benefits. These include:

  • saving water by reducing evaporation. California canals lose from 1-2% of their water annually. Saving water means more for farmers and consumers.
  • shade from the panels helps mitigate aquatic weed growth, a major canal maintenance issue
  • providing a new source of clean energy and new electricity that can be fed into the grid. Currently 80% of US energy comes from fossil fuels although renewables are making headway. 
  • reducing CO2 emissions and improving air quality. This would happen because farmers wouldn’t have to use diesel generators they traditionally use to pump their water.

As exciting as these benefits are, and as much as they would help alleviate California’s water woes, there are those who say it’s too soon to dive into this kind of project.

Mark Kapczynski, Chief Marketing Officer of Energy Shares, says the timing isn’t right.

Energy Shares – a centralized platform where investors and project developers can connect in order to fund projects and accelerate the adoption of renewable energy in the United States – helps utility scale projects get off the ground.

Kapczynski says “the thought of solar panels on waterways seems like a great option. You can deploy panels on a wide-open body / space and take advantage of natural cooling and contours. The real issue is, depending on the volume of coverage on the body of water, this would become the sole use of the waterway, greatly (limiting) the use of waterways today and for the future, even as our needs for water change and evolve.”

Also, he added, “there are unknown effects to the species of fish and marine life at this point to know the full impact over time. The country needs scale and getting it going faster. We need to achieve greater scale with solutions that produce enough power to offset that which uses fossil fuel / coal.”

The research has to be done about the impact of the canals, Kapczynski noted.

“There’s plenty of open land that’s ripe and ready to go,” he said. “Solar covered canals are still experimental,” Kapczynski said. “What’s the bigger solution?  We need to look at the bigger wins.”

This is a large topic. Where innovation is involved, it’s important to realize and remember for every new and wonderful solution, there are ALWAYS new problems and issues to be considered and factored in.

The next article on this subject will look at these issues – the potential downside of having solar covered canals – their impact on water fowl, on the environment and on the canal beds themselves. Yes, solar covered canals hold tremendous benefits. But remember that two-sided coin? We have to look at all the issues, see their effects and ramifications and factor in ALL the data. Then we’ll have the whole picture.

Meanwhile, Project Nexus is moving forward and cities and countries around the world are taking notice. The Los Angeles City Commission is considering implementing a similar project although it hasn’t yet voted on this idea. And Jordan Harris and Robin Raj, the sustainability entrepreneurs and founders of Solar AquaGrid, are regularly fielding query phone calls from across the globe.

There’s more to learn about what this project means – to California and to the rest of the country facing ever increasing drought and decreased water resources. It’s impact and the ripples it creates will be seen and felt for decades to come.

So make sure to come back for Part 2!

Author Bio: Debra Atlas is an environmental journalist, author, workshop leader and professional speaker. She can be reached through, or [email protected].

1 Comment

  • Hans-Henning Judek

    Allow me to introduce myself. I am one of the oldest hands in floating solar, starting in 2013 when only 1.2 MWp were installed on water. In 2014 I established the LinkedIn group “Floating Solar” which has meanwhile 2300 specialists as members. So you can expect a certain degree of expertise in my opinion.
    After reading an article about the massive evaporation from Lake Mead in 2014, I became interested in finding a solution to reduce this loss of precious water, namely with floating solar. I contacted the water authorities with very frustrating results.

    This is what I wrote my partners in the US concerning solar on the canals

    (Quote from 2014) ” I do not push it anymore, as it means pushing water uphill (pun intended.) Interestingly enough is the SWP (State Water Project) against such plans. They claim “The reality is that there’s an insignificant loss of water from evaporation on the aqueduct.”
    That coming from a water specialist makes me cringe. Even Lake Superior, which is not really in a hot region, is known to lose more than 2ft per annum to evaporation. In hot and dry areas, like California, the figure is up to 5ft or 1.5 short tons per square yard. Lake Mead in Nevada is losing between 2.1 and 1,9 meters (81.65 and 74.07 inches.) That is well-researched and can be considered a given. Insignificant?
    Covering only the California Aqueduct with floating solar could save 40 (!) million tons of water from evaporation – that is 81 days of the whole water supply for Sacramento. Calling that insignificant in view of the drought is … strange.
    …they seem to have maintenance concerns for the Aqueduct. So why not go for the lower-hanging fruit and propose an installation on the San Luis Reservoir or the O’Neill Forebay? The reservoir is huge (5100 ha; 12,750 acres), and the pumping stations with their big appetite for power are right next to it. The O’Neill Forebay area in front of the pumping station, without considering shadowing or water depth would have about 4MWp potential.” (End of quote) So that should definitely be the next step after the aqueduct.

    When I saw the canopy solution that is now proposed, I was scratching my head. Can this be a solution for all of the aqueducts? My first concern was the argument back in 2014 – maintenance problems. What the photos show is definitely limiting the accessibility to the canals.

    My idea for preventing this problem was that of a “block puzzle” for children. This is a wooden square with numbered blocks. One is left out and you have to shift the blocks to establish a given number sequence. Shifting the floats would give full access to the segment to be worked on.

    The second concern I had was that this configuration may not even prevent evaporation. There are three sources of heat acting on the water.

    1. The sun’s irradiance – which can be fully prevented by shadowing
    2. The convection heat seeping into the water from the surrounding land on the sides of the canal.
    3. The convection heat from the air, which cannot be limited by the canopy. On the contrary. Solar modules heat up on summer days to 65-80°C ( 150-175°F). They will act like a panel heater in your living room and heat up the air below it, which in turn heats the water. Add a little wind, blowing away the protective moisture barrier on the surface, and evaporation is increased substantially.
    I think it is of utmost importance to address these topics during the test phase. Maybe even in direct comparison with a floating solar solution that can trap the moisture 100%.

    If you would like to discuss this matter with me, contact me through my LinkedIn profile.

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