Towards optimal design of photovoltaic/thermal facades: Module-based assessment of thermo-electrical performance, exergy efficiency and wind loads

Abstract

A remarkable amount of solar energy can be harnessed for generating renewable energy by applying giant photovoltaic/thermal systems to the façades of structures. However, the applicability of these systems is overshadowed by two key parameters of building geometry and complex wind behavior. This study aims to present a clear benchmark for the applicability assessment of these systems by predicting wind complexity and identifying the position of modules with critical temperatures and wind loads prone to jeopardy and destruction. For this purpose, four hundred integrated photovoltaic modules are applied to the façade of a high-rise and a mid-rise tower with the same capacity (12000 m3) and photovoltaic façade area (600 m2), and the temperature, wind load, and thermal/electrical efficiency are studied for one by one of them. The evaluation is conducted for various wind speeds using state-of-the-art computational fluid dynamics models. The results reveal that each module undergoes different wind loads and temperatures relative to its neighboring modules and has an exclusive thermoelectrical performance in the entire system. The temperature difference among the modules exceeds 55 °C, and some modules experience operating temperatures higher than 100 °C. Based on the results, both mid-rise and high-rise structures have almost the same potential for power supply, with a maximum of 70 kW obtained at the highest wind speed, while the high-rise structure is more suitable for heating production, with a maximum of 115 kW obtained at the lowest wind speed. Therefore, more energy is produced in the high-rise tower compared to the mid-rise one. Moreover, the maximum total energy and exergy efficiencies of the system reach 33.28 % and 21.2 % in the mid-rise building and 37.05 % and 20.9 % in the high-rise building, respectively. Overall, the findings of this study give a guideline for future sustainable constructions and optimal designs of façade-based photovoltaic/thermal systems.