Validation of a rooftop photovoltaic module in large-eddy simulations using eddy-covariance observations

The rapid expansion of rooftop photovoltaic (PV) systems in urban areas provides substantial renewable energy capacity while also modifying surface radiative and turbulent energy exchange in the urban boundary layer.  As a result, PV installations can contribute to phenomena such as the photovoltaic heat island (PVHI), which refers to increased ambient temperatures associated with heat absorbed and emitted by PV panels. Understanding these coupled effects is essential to assess PV impacts on the urban surface energy balance and boundary layer structure. Despite growing observational and mesoscale modeling studies, building-resolving large-eddy simulation (LES) investigations with direct comparison to rooftop measurements remain rare. In this study, we evaluate a newly developed rooftop PV energy balance module implemented in the LES model PALM. The module solves the PV surface energy balance with temperature dependent conversion efficiency, providing a physically consistent link between radiative forcing, PV surface temperature, thermal and turbulent exchanges, and power production. Simulations are conducted for a large industrial rooftop near Dresden, Germany, equipped with approximately 2,700 PV panels, using realistic building geometry and multiple representations of rooftop PV layouts. Three clear-sky days representing summer and winter conditions are simulated and compared against rooftop observations, including eddy-covariance (EC) measurements of sensible heat flux, near-surface air temperature, PV surface temperature, and recorded power output. We analyze the ability of the PV module to capture the observed diurnal evolution across these thermal, turbulent, and electrical variables. Sensitivity experiments investigate the influence of grid resolution and different rooftop PV layout representations on thermal and turbulent exchange processes. This work aims to advance the understanding of interactions between rooftop PV systems and the urban boundary layer and to support future interpretation of PV impacts on the urban boundary layer.