A combined photovoltaic-thermal (PV-t) panel to minimize the electrical and air conditioning energy consumption of a typical office in Beirut -

Abstract

A combined photovoltaic-thermal (PV-t) panel produces simultaneously electricity and heat from one integrated component to utilize effectively the solar energy by achieving higher PV electrical efficiency and making use of the dissipated heat energy for heating applications. The modeling of the system used the following models: a space model used by Yassine et al. (2012) and validated using TRNSYS, a desiccant model developed and validated by Beccali et al. (2004) and an evaporative cooler model implemented by Kinney (2004). As for the PV-t model, a transient mathematical model for the PV-t was developed based on the formulation of Kumar (2011) to predict its performance for given environmental conditions and flow rate of ambient air that cools the PV-t panel. The model was validated experimentally and showed good agreement in predicting exit air stream temperature and electrical output of the PV-t. The models were integrated in a heating application for a typical office space in the city of Beirut to provide the office needs for electricity, heating during winter season, and dehumidification and evaporative cooling during the summer season. The optimization problem was formulated based on the electric energy consumption of the office, the thermal energy consumption of the desiccant system, and the electrical and thermal energy extracted from the PV-t panels, with the appropriate constraints associated with the different models, and those that satisfy the thermal comfort criteria (Predicted Mean Vote value between -0.5 and 0.5). The optimization problem is solved on an hourly basis for the period of occupancy from 7 a.m. till 5 p.m., and only ventilation is set on during the night. The Genetic Algorithm was used to optimize the system’s performance to minimize the yearly office energy (electrical and heat) consumption, and ensure the operation at minimum cost while maintaining thermal comfort inside the space. The decision variables being the air mass flow rate and the desiccant regeneration temperature,