Floating photovoltaic (FPV) platforms in a French Polynesian lagoon substantially reduced the amount of light reaching the seabed but produced no detectable change in water temperature, according to a year-long study.
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platforms → float → study
Researchers monitored four FPV platforms and a control area in the lagoon of Tumaraa on Ra’iātea from August 2024 to September 2025.
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Researchers → monitor → September
The platforms reduced photosynthetically active radiation reaching the benthic environment, with stronger attenuation recorded beneath platforms designed for higher shading levels.
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platforms → reduce → levels
Measurements also showed substantial reductions in UVA and UVB radiation beneath the platforms.
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Measurements → show → platforms
Despite these changes in underwater light conditions, estimated temperature differences remained below the study’s sensor accuracy.
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differences → estimate → accuracy
How did floating solar platforms reduce seabed light
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platforms → float → light
According to the study published in the Journal of Marine Science and Engineering, titled ‘
The Effect of Shading by Floating PV on Light and Temperature in a Tropical Lagoon’, the researchers monitored photosynthetically active radiation (PAR) from August 2024 to September 2025 across four FPV platforms and a control area.
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researchers → accord → platforms
Light sensors were positioned at a depth of 1 metre and recorded measurements every 15 minutes.
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sensors → position → measurements
The study reported that the FPV platforms substantially reduced the amount of light reaching the benthic environment, with shading intensity identified as the main determinant of attenuation.
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intensity → report → attenuation
The results showed stronger attenuation beneath the platforms designed for 81% shading than beneath those designed for 51% shading.
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results → show → shading
At one monitored position, the reported attenuation coefficients were 3.3 under SH51, 3.5 under SH51-UV, 10 under SH81 and 8.1 under SH81-UV.
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coefficients → monitor → UV
At another position, the corresponding coefficients were 4.1, 5.2, 18 and 8.8.
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coefficients → correspond → position
The study also found spatial variation beneath some platforms, with localised shading contributing to differences in the amount of light reaching different positions.
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shading → find → positions
How did floating solar platforms reduce UVA and UVB radiation
The study separately examined ultraviolet radiation beneath the four FPV platforms and a control area.
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study → float → platforms
UVA and UVB measurements were taken at depths of 1, 1.5 and 2 metres on three occasions between June and November 2024.
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measurements → take → June
The researchers reported that both UVA and UVB irradiance declined strongly beneath the FPV platforms.
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irradiance → report → platforms
Between 1 and 2 metres depth, UVA intensity decreased by factors of approximately 1.9 under SH51, 5.0 under SH81, 8.2 under SH51-UV and 14.3 under SH81-UV.
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intensity → decrease → UV
For UVB, the corresponding decreases were approximately 2.41, 3.5, 6.9 and 9.6.
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decreases → correspond → UVB
The study also found that the visible-light spectrum was affected mainly through changes in irradiance intensity, with only minor spectral changes above 600 nanometres.
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spectrum → find → nanometres
Image AI generated
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AI → generate → ?
How much did water temperature vary under FPV platforms
Water temperature was monitored across the four platforms and a control area from August 2024 to September 2025.
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temperature → monitor → September
Sensors were installed at 1 metre depth and recorded temperatures every 15 minutes.
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Sensors → instal → temperatures
During the study period, temperatures in the control area followed a seasonal cycle, ranging from 26.9°C in July and August to 29.4°C in February.
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temperatures → follow → February
Although the statistical analysis identified lower temperatures under FPV conditions compared with the control, the estimated differences relative to the control ranged from −0.06°C to 0°C.
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differences → identify → C
The study states that these differences did not exceed the propagated accuracy of the temperature sensors, which was 0.28°C.
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which → state → sensors
Consequently, despite the substantial reduction in irradiance, the researchers reported that the FPV platforms did not produce detectable or biologically meaningful changes in water temperature.
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platforms → report → temperature
The researchers attributed the absence of a measurable thermal effect partly to the characteristics of the lagoon environment and the relatively small size of the experimental platforms.
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researchers → attribute → platforms
The discussion notes that strong water mixing and the platforms' limited footprint could prevent the development of localised cooling effects.
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mixing → note → effects
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