A researcher observed fish gathering beneath the floating solar panels as the water warmed.
The study took place on a pond in Ontario, Canada.
The team wanted to test a small floating solar power system through both summer and winter.
But as the pond warmed, the panels appeared to be doing more than simply producing electricity.
Over the next year, they tracked how the array performed as conditions around the pond changed.
Why fish kept returning to one patch of water
Researchers used a floating 7 kW photovoltaic (PV) array.
The system consisted of semi-flexible monocrystalline solar modules attached to closed-cell polyethylene foam.
This allowed the system to float on the water.
Researchers tracked the system from August 2024 to June 2025 as the pond went through both summer and winter.
They collected data on environmental factors such as air temperature, water temperature, module temperature, and electrical output.
On multiple occasions, researchers documented fish gathering beneath the PV array during the hotter parts of the day.
In addition to providing shading, the PV array also impacted evaporation from the pond.
Since some of the pond’s surface is shaded by the PV array, less water evaporated from the pond during warmer months.
The ice problem sitting beneath the panels
The array performed well in terms of generating electricity but operating it throughout a Canadian winter presented some challenges as temperatures fell.
In particular, the researchers were concerned about ice forming underneath the array.
To prevent ice from forming under the PV array, researchers added air delivery tubes under the panels.
The tubes blew air under the panels to create bubbles that lifted water upwards and prevented ice from forming on top of the water.
The researchers tested their solution and found that they were able to maintain open water around the PV array even when the pond was covered by ice.
Operating the bubbler also required some energy.
Researchers estimated it consumed between 0.02% and 14.5% of the array’s total energy production, depending on airflow.
The researchers also determined that the foam-backed PV system generated approximately 7.7 megawatt-hours of electricity per year.
Their regression model showed that this was 0.5% to 2.7% more energy than predicted by five different PV temperature models included in their analysis for comparison.
Three percent coverage changed more than expected
Only about three percent of the pond was covered, but researchers modeled what would happen with greater PV coverage because evaporation decreased as coverage increased.
When modeling ten percent coverage, researchers estimated that approximately 185 cubic meters of water would be conserved each year.
When modeling fifty percent coverage, researchers estimated that approximately 927 cubic meters would be conserved each year.
The 10% coverage scenario represented a nine percent reduction in evaporation.
The 50% coverage scenario represented a forty-five percent reduction in evaporation rates.
On one hand, the array produces electricity.
On another, it shades part of the pond during hot weather and reduces evaporation.
It also provides a means to generate electricity through winter months using bubble technology.
The question the fish may answer later
The schooling of fish beneath the Photovoltaic (PV) array is likely one of the most fascinating observations made during the study.
While researchers believe that this observation could have implications for aquatic organisms in general, additional investigation will be required to fully assess them.
Long-term use of underwater video cameras, acoustic tagging, or other biological or ecological monitoring techniques would provide information about whether these shaded water bodies would continue to be a habitat for aquatic animals.
APA CITE: Hayibo, K. S., Rahman, M. M., & Pearce, J. M. (2026). Design and thermal-energy performance analysis of foam-based floating photovoltaic systems in a cold climate: experimental results from a 7 kW floatovoltaics in Canada. Applied Energy, 420, 128159.
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