Influence of row spacings on the thermal performance of floating photovoltaic arrays at the Occhito Dam reservoir, Italy: A numerical study

Floating PhotoVoltaic (FPV) systems are becoming increasingly popular for reservoir-based solar installations, as they help avoid land use conflicts and may benefit from a more favourable thermal environment compared to ground-mounted systems. However, the thermal advantage of FPV is not guaranteed and heavily depends on local wind conditions, array geometry, and wake interactions between adjacent rows. This study investigates the thermal behaviour of an FPV array proposed for the Occhito Dam reservoir in southern Italy using a two-dimensional conjugate heat transfer model in OpenFOAM. Four row spacings (0.25 L, 0.5 L, 0.75 L, and 1.0 L) are assessed at two inlet wind velocities (1.5 and 3.5 m/s) based on site-specific meteorological data. The numerical model is validated against available literature data, reproducing the same trend in panel temperature with increasing wind speed, with a mean absolute deviation of about 1.95 °C. Among the configurations, the 0.5 L spacing produces the lowest average panel temperature: 37.02 °C at 1.5 m/s and 27.16 °C at 3.5 m/s. The central row is most affected by row spacing, indicating that the thermal behaviour of the array’s inner part depends on airflow recovery from the upstream row and convective heat transfer between rows. Overall, the results indicate that a moderate spacing provides the most effective balance between reducing wake effects and enhancing cooling performance within the array. These findings provide a useful basis for the preliminary design and optimisation of FPV layouts for the Occhito Dam site, although further three-dimensional and electro-thermal investigations are still required.