French researchers have developed a high-resolution computational framework to model the microclimate effects of large floating solar PV systems, enabling accurate predictions of heat transfer, ambient temperatures and water evaporation based on panel configuration and wind conditions. The model can inform thermal performance and environmental impacts and optimize designs for utility-scale floating PV, as well as ground-mounted and agrivoltaic installations.
French researchers have developed a framework to model the microclimate effects of large floating PV systems.
The new model can be used to determine wind-dependent convective heat transfer coefficients (CHTC) and ambient temperatures and to estimate evaporation patterns in partially covered water bodies based on different tilt angles, module heights and pitch distances.
“The main novelty of this work lies in the numerical methodology we developed, in particular a scale-up method to quantify panel-atmosphere interactions at the module scale and then model the micrometeorology at the power plant scale with a relatively fine resolution of around 4 meters,” Baptiste Amiot, corresponding author of the study, told us. pv magazineadding that its resolution is significantly higher than others in this field.
“By applying this methodology, we can map the thermal performance of utility-scale installations and provide insight into local environmental impacts, such as evaporation losses,” he said.
The predecessor model is geometrically adaptable: according to Amiot, it can handle different tilt angles, mounting heights and distances between the rows. “It is particularly suitable for large-scale installations exposed to sufficiently windy conditions,” said Amiot.
The researchers used a computational fluid dynamics (CFD) precursor model, a microclimate CFD model supporting the PV parameterization, and an experimental study. To confirm the accuracy of height-based wind profiles, a wind tunnel setup typical of a land-based application was used.
In addition, a geometric layout of a commercial floating PV plant (FPV) was used for the atmospheric boundary layer parameters. The wind direction effects were assessed using the microclimate CFD model that reproduced the local conditions of the commercial FPV array.
“The atmospheric component is fundamentally similar to regional climate models (RCMs), but its deployment within a CFD framework offers advantages in terms of parameterization of surface elements and the spatial discretization we can achieve,” Amiot said.
Some of the findings include temperature gradients between 1.3 C/km and 5.8 C/km; headwinds and tailwinds relative to the front surface of the PV modules generate the greatest levels of turbulence. Additionally, the team was able to investigate how turbulent flows influence water savings benefits based on PV coverage of the water surface.
Reviewing the results, the researchers noted that the precursor method “easily determines” the correlations of the heat transfer coefficients as a function of wind speed and direction. “This is essential to achieve the thermal U-values that control panel cooling,” says Amiot.
The model can be extended to model large ground-mounted systems and agricultural voltaic systems, including dynamic configurations where panels adjust orientation throughout the day, Amiot said. It is suitable for inland and nearshore FPV, but not for offshore FPV.
The work is described in detail in “Boundary layer parameterization for assessing temperature and evaporation in floating utility-scale photovoltaics”, published in Renewable energy. Research participants include Ecole nationale des ponts et chaussees, Electricité de France RD and Université Claude Bernard.
The researchers are currently focused on developing CFD models to predict both the energy yield and ecological trade-offs of dual-use photovoltaic systems and FPV evaporation research at finer spatial scales, coupled with in-situ measurements. The company is also working on an agrivoltaic CFD factory model to predict the response of crops under PV roofs.
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