Solar Tribune

Floating Solar Panels Sail Forward


As solar energy has become more mainstream, solar panels have found their way onto more and more unique places, from theme parks to airports to old landfill sites. Floating solar panels offer an even more creative use for solar that fundamentally alters conventional assumptions about solar generation opportunities.

How Do They Work?

Solar panels themselves are an engineering marvel, and floating solar panels are even more so. Metal components are a significant part of land-based solar energy systems, which presents a challenge for floating solar panels since metal and water are not a good mix. Ground mounted solar panels are installed on mounting systems that are typically anchored into the ground by a steel helical pile.

Floating solar panels on the other hand are typically placed upon polyethylene-based “floaters,” which are buoyant and strong enough to hold 2.5 times their weight. The floating structure itself is coated with magnesium alloy, which is highly resistant to corrosion and rust. The floating solar structure is kept in place via mooring lines and anchors that rest at the bottom of the body of water.

Just as ground-mounted systems typically require flat terrain, floating solar energy systems require calm waters with minimal choppiness. You won’t find them out on the open ocean. Instead, you’ll find them on lakes, canals, and similar (often man-made) bodies of water.

To date, floating solar has mainly been installed overseas. The largest floating solar arrays are all in Asia, including the largest such installation in the world, the mammoth 320 MW Dezhou Dingzhuang floating solar array in China.

Meanwhile, Portugal is home to Europe’s largest floating solar array with a 5 MW, 12,000 panel system located in the region of Alqueva.

Pros and Cons

Floating solar panels are a revolutionary technology that are disrupting conventional approaches to generating solar energy. Floating solar panels present a number of advantages over land-based alternatives, and some flaws as well. Here are some of the main pros and cons of floating solar panels.


  • Cooling effect allows for better efficiency: A common issue with solar panels is that the rising panel surface temperatures resulting from a long sunny day can actually reduce panel efficiency. Floating solar panels are able to mitigate these efficiency loss issues thanks to the cooling effect of the water on the underside of the panels.
  • No loss of land: Arguably the biggest advantage of floating solar panels is that they do not occupy otherwise scarce land that in turn can be freed up for other residential, industrial, commercial, or land preservation purposes. This is an especially useful evolution in an era where community pushback against large solar farms is becoming increasingly common.
  • Compatibility with hydropower plants: Floating solar is most often found on calm, man-made bodies of water like lakes and reservoirs. Hydropower power plants have such a dammed reservoir nearby, which presents an attractive “double whammy” opportunity to generate power at these locations. Power generated by floating solar panels on these reservoirs can benefit from the existing infrastructure at the power plant, helping to reduce costs and making it easier to send power to the grid.
  • Shade avoidance: Vertical obstructions are a no-no for optimizing solar energy production since they can shade  solar panels and reduce system efficiency. The benefit of floating solar panels is that they are typically placed on expansive open bodies of water, helping to remove the threat of shade. There are subtle environmental benefits as well since the removal of trees, which can be common for ground-mounted systems, is not applicable to floating solar energy systems.


  • Higher maintenance costs: Floating solar is still a relatively new technology. The specialized equipment it requires and the niche knowledge and experience required of floating solar installers helps lead to higher installation costs. Long-term maintenance costs are also higher for similar reasons. There are unique costs like the cleaning costs associated with bird droppings arising from birds roosting on or near the floating solar panels.
  • Disruption to aquatic life: The floating solar panels block out sunlight below, which can deprive aquatic plants of key nutrients and disrupt sensitive aquatic ecosystems. Aquatic life is typically sparse on man-made lakes and reservoirs where floating solar panels are most typically located, so this helps to mitigate widespread harmful effects. There are also some subtle benefits to the shade cover like reducing the presence of dangerous algae blooms.

California Canals

Floating solar panel systems are much more prolific internationally than they are in the United States. The largest U.S.-based floating solar farm is a 4.8 MW system sitting on two ponds at Healdsburg, CA’s wastewater treatment plant. This system is dwarfed by the 320 MW Dezhou Dingzhuang floating PV array in China.

California is seeking to help the U.S. along and make water-integrated solar panel systems more mainstream by employing a unique adaptation to long running efforts to mitigate drought effects. If it were a country, California would have the 4th largest economy in the world. Much of California’s modern-day success is owed to the state’s elaborate aqueduct system which was initially constructed some 60+ years ago. The state’s aqueduct system includes over 4,000 miles of canals designed to deliver water from wet Northern California to comparatively dry Southern California.

The State of California is hoping to complement this series of man-made canals with solar panels. The state-funded effort, dubbed “Project Nexus,” will affix solar panel canopies over three sections of the Turlock Irrigation District (TID), totaling approximately 8,500 feet of space. Construction on the project is expected to commence in 2023.

Photo Source:

The marriage between solar canopies and canals can help to solve dual issues in California. The shade cover provided by the canopies can help to combat omnipresent drought concerns in California by reducing evaporation, while the solar canopies add another tool to the state’s toolbox to achieving 50% clean energy generation by 2025 and 60% by 2030.

Researchers at UC Merced and the University of California Santa Cruz first planted the idea of ‘solar canals’ in a study published last year in Nature Sustainability. The hope is that this pilot project shows promise and can be scaled up significantly across the state. The researchers estimate that the water saving effects and solar generation potential will be profound. According to their research findings cited in a recent PBS article:

The research suggests that covering all of California’s canals – spanning roughly 4,000 miles – with solar panels could save up to 63 billion gallons of water and generate 13 gigawatts of renewable power annually. One gigawatt is equal to the energy consumption of 100 million LEDs, or as others put it, enough to power 750,000 homes.

It would have been preposterous a couple decades ago to think that floating solar panels or solar panel canopies built over Californian canals would ever be feasible. The emergence of these water-integrated solar innovations is yet another reminder of how groundbreaking technologies are continuing to open up new possibilities for how we harness the Sun’s power.

Floating solar in particular is just barely scratching the surface when it comes to its long-term potential. Currently, only 2% of new solar installations are on water, yet the United States has more than 24,000 human-made bodies of water. It will be fascinating to follow the growth in the floating solar panel industry in years to come. The prospects are clearly bright.


Cover Photo Source: NREL

Recent Posts