Opaque ventilated façade (OVF) with electricity conversion: analyses on a real installation

To face buildings overheating during the summer season a very promising alternative is represented by the ventilated façades. In this work, it is analyzed a special ventilated façade whose external layer consists of photovoltaic panels. Such a solution combines the advantage of an opaque ventilated façade (OVF) with the increase of the photovoltaic (PV) performance due to lower operating temperature. Indeed, the efficiency of the photovoltaic modules decreases with their temperature. The critical aspects concerning the modeling of this component are investigated, and alternative cases are also compared, by considering both winter and summer conditions. The radiative characteristics of the photovoltaic panels are not typically reported on technical data sheets. The solar radiation absorption coefficient is an unprovided data that however profoundly affects the behavior of the system. Hereinafter a CFD model is presented to replicate the configuration of the wall of the new lab called H-MOLISE. Thermal, fluid-dynamics, and energy analyses demonstrate the effects of the radiative characteristics and environmental conditions (global incident radiation and outdoor air temperature) on system temperature (PV and air gap), air movement and PV efficiency. With a solar radiation of 600 W/m2 and an outdoor temperature of 35°C the average temperature of the modules increases of around 7°C while the efficiency reduces from 0.185 to 0.179 by changing their absorption coefficient from 0.7 to 0.9.