Multiple-inlet Building Integrated Photovoltaic/Thermal system modelling under varying wind and temperature conditions

Air-based, open-loop Building Integrated Photovoltaic/Thermal (BIPV/T) systems are an efficient means for generating electricity and useful heat from incident solar energy. However, due to the low heat exchange efficiency of air, overheating issues may occur that can reduce the electrical production of the system, as well as its durability. With the introduction of multiple intakes of air along the PV string, the goal is to improve the heat extraction from all PV panels, while achieving lower and more uniform PV temperatures. This study presents the results of a numerical investigation on the comparison of the performance of single and multiple-inlet BIPV/T systems for a possible retrofit or new buildings, with an example of a potential large scale installation on an office building. The comparison was carried out considering a cold winter and a hot summer day, under varying wind conditions, in terms of electrical and thermal performance, and PV temperature distributions. For the modelling of a multiple-inlet BIPV/T system, a flow distribution model was developed utilizing pressure drop and flow correlations, as well as wind tunnel pressure measurements representing the wind effects on the flow distributions, and a modified energy balance model for the multiple-inlet system. It was found that a multiple-inlet BIPV/T system may have up to 1% higher electrical efficiency corresponding to 7% additional power to the total output of a 120 kW system and up to 24% higher thermal efficiency, while resulting in the lowest and most uniform PV temperatures. (C) 2016 Elsevier Ltd. All rights reserved.