Experimental and numerical study of optimizing thermal and electrical performances of the photovoltaic wall through array row spacing

Abstract

Facade-integrated photovoltaic modules are often restricted to parallel walls, causing poor heat dissipation and leading to overheating as well as power loss. This study combines experimental and numerical approaches to optimize vertical (height) and horizontal (width) inter-row spacings for photovoltaic panel with optimal layout graphene sheet, enhancing heat dissipation and maximizing installation density. Experiments reveal that two vertically stacked panels with zero spacing compared with the single panel, exhibits an average temperature rise of 1.93°C, power reduction of 0.68 W/m², and exterior wall temperature increase of 1.16°C. In contrast, two horizontally stacked panels with zero spacing show milder performance degradation, which exhibits 0.97 °C increase in average temperature, 0.35 W/m² decrease in average output power and 0.78 °C rise in average exterior wall temperature. Furthermore, experiment conducted with height spacings of 50, 100, 150, and 200 mm demonstrate that the rate of thermal and electrical performance improvement plateaus when height spacing surpasses 150 mm. Similarly, experiments on different width spacings show that performance improvement becomes marginal when width spacing exceeds 100 mm. Numerical simulations of 2 × 2 panel arrays confirm that height spacing of 150 mm and width spacing of 100 mm optimally balance cooling and spatial efficiency, with results aligning with experimental data and highlighting the dominant role of height spacing in natural convection. Finally, the airflow velocity images in air gap are analyzed, and results mechanistically validate experimental observations. Our findings provide more comprehensive and practical solution for enhancing photovoltaic wall performance in urban environments.