One-dimensional transient thermal modelling and analysis of pontoon design parameters in floating photovoltaic systems

• Thermal model to predict temperatures in floating photovoltaic modules developed. • Model achieves R 2 = 0.91 and 4.00 °C average error with 46 days of test data. • Elevated pontoon temperature reduces thermal benefits of module proximity to water. • Sensitivity analysis shows pontoon surface area most affects module temperature. • Model predicts 0.21% increase in average module efficiency without the pontoon. This study simulates the thermal behaviour of floating photovoltaic modules under varying conditions of plane-of-array irradiance, wind speed, air temperature, and water temperature. A transient, one-dimensional finite difference model calculates cell temperature, efficiency, and power output. Validated using 46 days of experimental data from a floating photovoltaic system in Stellenbosch, South Africa, the model predicts back surface temperatures with a root mean square error of 4 . 00 °C and R 2 = 0 . 91. Strong correlations of R 2 = 0 . 92 and R 2 = 0 . 90 are observed under consistent and fluctuating irradiance conditions, respectively. Elevated pontoon temperatures ( T P > T air > T W ) are found to reduce the thermal benefits of water proximity. A factorial design sensitivity analysis examines the influence of module tilt angle, pontoon emissivity, relative pontoon surface area, module height above water, and their interactions on cell temperature. Pontoon surface area shows the highest sensitivity, with an average change of 0.22 °C / %, followed by tilt angle. Pontoon emissivity has a lower but notable sensitivity of 0.05 °C / %. Significant parameter interactions are also identified. Modelling a pontoon-less floating photovoltaic system reveals a mean module efficiency increase of 0.21 % (maximum 0.39 %) and a 1 . 28 % rise in energy output across the dataset, highlighting the pivotal role of pontoon design in optimising the thermal performance and overall efficiency of these systems.