The energy transition is driving us to explore innovative solutions for producing renewable and environmentally friendly electricity and floating solar in one of them. This technology relies on photovoltaic panels installed on floats on the surface of artificial water bodies. The main goal is to use spaces already exploited for another activity: flooded quarries, industrial basins, recreational ponds…
In addition, this approach offers several advantages: no competition with agricultural land and enables the preservation of precious land, greater efficiency thanks to natural water cooling under the PV panels and use of unexploited or underutilized surfaces.
However, this innovation highlights a crucial question: What are the impacts on aquatic and terrestrial biodiversity?
The lakes and reservoirs are sensitive ecosystems, where environmental parameters such as light, temperature and oxygenation determine the life of many animal and plant species. Some mentioned the positives aspects of FPV, as limiting evaporation or reducing harmful seaweed, while others fear disruption to fish, birds and insects. Research or European collaborative projects such as SOLAKE seek to provide scientific answers to these questions.
Why is floating solar so appealing?
An innovative solution to produce renewable energy
Firstly, floating solar power plants involve installing photovoltaic panels on floats, placed on water bodies. Depending on the project and site constraints, these installations can cover part of the surface or a larger area. The floats are designed to withstand environmental stresses such as waves, water level variations and climatic conditions.
Concrete benefits of floating solar: yield, land and water savings
Specificities of these technologies offer concrete benefits:
- Improved efficiency: Water cooling and an average density of 1,5 MWp per hectare maximize the electricity production.
- Water conservation: floating panels reduce evaporation from lakes and reservoirs.
“The most relevant FPV advantage in the present context is a reduction by up to 70% in evaporation loss” (Redón Santafé et al. 2014, Abdelal 2021, Bontempo Scavo et al. 2021, Santos et al. 2022) - Land savings: avoids using agricultural or natural land.
- Utilization of otherwise unused sites: flooded quarries or industrial reservoirs “become productive” in addition to their main activity.
Insights from scientific research
SOLAKE project: understanding aquatic biodiversity impacts
The SOLAKE project is a research project conducted by the Department CRBE at Toulouse III University, CNRS Images, that aims to analyze effects of floating photovoltaic plants on freshwater biodiversity and ecosystems.
The SOLAKE project studies the impact of floating photovoltaic systems on 22 quarry lakes in southwest part of France and sets up a five-year monitoring programme for aquatic parameters within floating photovoltaic projects. This monitoring will be carried out on the seven bodies of water in the Southwest of France (as well as three other control ponds with similar characteristics ) and the following parameters will be evaluated:
- Environmental (temperature, dissolved oxygen);
- Seasonal biotic aspects (phytoplankton, zooplankton);
- Abiotic aspects (physico-chemistry);
- Function of the ecosystem and fish communities (scientific fishing).
Thanks to early monitoring, some short-term findings have already emerged.
Confirmed positive aspects of floating solar
Water temperature decrease
One of the most direct effects observed with floating solar systems is the measurable decrease in water temperature beneath and around the installations. This temperature reduction occurs primarily because the solar panels shade the water surface, limiting direct solar radiation and thereby slowing heat absorption. A three-year study conducted on French gravel pit lakes (University of Toulouse, 2020-2023) found that floating photovoltaic arrays reduced average water temperatures by about 1.2 °C compared to nearby reference lakes without installations. During summer heatwaves, the difference reached nearly 2 °C, and under certain conditions, reductions of up to 3 °C were recorded. This decrease can help mitigate thermal stress on aquatic ecosystems, a valuable effect in the context of global warming
Shading effect
Another positive aspect is the shading effect of the panels. By blocking part of the sunlight, floating solar reduces the growth of harmful algae, which thrive in warm, light-rich environments. Excessive algae can deplete oxygen levels and release toxins that threaten fish, invertebrates, and even water quality for human use. Early results show that shaded areas often experience clearer, healthier water conditions. However, it should be kept in mind that this shading effect depends on the technology chosen and the coverage rate.
Reducing evaporation
In addition, floating PV panels help reduce evaporation, preserving significant amounts of freshwater in reservoirs and lakes. A benefit that is particularly valuable in regions facing drought or increasing water stress.
Perhaps most importantly, ecological monitoring carried out during the first months of operation has not revealed major disturbances to local fauna as mentioned this article. Fish continue to circulate in shaded and open zones, invertebrates remain present, and bird activity around the reservoirs has not shown drastic changes. These early results suggest that, when carefully designed and installed, floating solar may integrate into aquatic environments without immediate negative impacts.
Potential early disturbance
At this stage, researchers underline the complexity of understanding the impacts of variations in environmental parameters on the trophic chain.
For example, some fish may avoid heavily shaded areas initially, while invertebrates could change their vertical or horizontal distribution. Birds that feed on aquatic life might temporarily shift their foraging patterns. These behavioural responses are subtle but highlight the need for monitoring.
This is particularly true because these changes in the ecosystem occur gradually and over the long term. In the coming years, researchers will therefore work to understand how lake organisms are affected by these long-term modifications. These future findings will help the scientific community develop strategies to ensure that the expansion of low-carbon energy does not come at the expense of biodiversity and ecosystem health.
Looking ahead: the future of floating solar and biodiversity
Overall, floating solar represents an innovative and promising solution for generating renewable energy while preserving land and water. Early findings suggest benefits for lakes and reservoirs, such as reduced evaporation, cooler water, and healthier aquatic environments. However, ongoing monitoring and long-term studies under projects like SOLAKE are necessary to fully understand the ecological impacts and confirm that floating solar technologies can be deployed sustainably without impactingocal ecosystems.
Author : Lilouann Nevelstyn
