- Covering 4,000 kilometers of canals would save 63 billion gallons of water and generate 13 GW of power annually
- Pilot project shows significant reductions in water loss and algae growth
- Critics argue that the project is too expensive and that preventing channel evaporation could be counterproductive
California’s extensive canal network could become a massive source of clean energy while saving billions of gallons of water each year.
A study by the University of California found that covering about 4,000 kilometers of canals with solar panels would generate 13 GW of power annually and save 63 billion gallons of water.
That amount of water is enough to cover the housing needs of more than two million people every year.
What the pilot project has proven so far
A small-scale demonstration called the Nexus project was built to test whether this concept actually works in real-world conditions.
The 1.6-megawatt Nexus installation sits on canals operated by the Turlock Irrigation District, and after a full irrigation season, the covered canal sections showed a 50 to 70% reduction in evaporation under the solar panels.
Algae growth decreased by 85%, which significantly reduces the costs of maintaining the channels and cleaning water pumps.
The shade also keeps the solar panels cooler than ground-mounted alternatives, improving their electricity output by about 2.5 to 5%.
India has already built similar solar projects on the canal, proving that the concept works across different climates and geographies.
Despite the clear benefits, this idea faces resistance, the biggest obstacle being cost.
Canal top solar requires heavy steel support structures to span the width of the water canal below, and these structures alone can account for up to 40% of the total project cost, significantly more than ground-mounted solar systems.
Critics argue that canals are designed for water supply, not as a basis for industrial infrastructure.
Such designs would require regular access to the ducts by maintenance personnel for desilting and repairs, and overhead panels would significantly complicate this work.
Some also point out that California has plenty of cheap desert land where traditional solar panels can be installed at a much lower cost.
Although a solar farm on desert land costs less and avoids the technical complications, it saves nothing on water, a long-standing California problem as the state has already lost 40% of its Colorado River allotment this year, and every drop saved counts.
What needs to change for widespread implementation
The economic calculus of this idea changes when water savings are assigned real monetary value.
Canal top solar prevents evaporation in a state that regularly faces severe drought conditions and also generates electricity exactly where there is agricultural demand, reducing transmission losses from distant desert solar farms.
From another vantage point, solar energy from the canal could ease the demand for data center power, which normally puts enormous pressure on local grids and water supplies.
It generates clean power exactly where it is needed, reducing transmission losses and avoiding the need for new transmission lines.
The water saved through evaporation reduction can be used to cool data centers instead of being lost to the atmosphere.
A single data center can use millions of gallons of water each year, and channel shading conserves this resource for productive use.
The 13 GW of potential output from California’s canals could power hundreds of data centers without requiring additional land or stressing the state’s overtaxed grid.
That said, preventing evaporation, which canal top solar will do, is not a guaranteed gain.
It is likely to have minimal impact on local humidity and may disrupt aquatic ecosystems by reducing dissolved oxygen, which is like solving one problem while creating another.
The Nexus pilot will continue to collect data to determine whether California scales the concept or decides the ecological and operational trade-offs are not worth the energy gains.
Via PV Magazine
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