Optimizing the Energy Production for a Photovoltaic Thermal (PVT) Water System

Abstract

The maximum exploitation of solar energy can be achieved through the optimization of a photo-voltaic thermal (PVT) system. In the PVT system, the (PV) module is cooled down by a water-based thermal collector, and as a result, electricity and hot water are produced. A novel zero-dimensional model is proposed to assess and optimize the performance of such a PVT system. The zero-dimensional model does not rely on spatial resolution or time-dependent variables. The model consists of thermodynamic relations that analyze the energy and the exergy of the PVT system. The validation of the model is performed by comparing its prediction parameters to the parameters collected experimentally from an in-house PVT system. The in-house PVT system consists of a polycrystalline PV module attached to a double series-parallel serpentine thermal collector. The zero-dimensional model predicts the difference between inlet and outlet water temperature as well as the PV surface temperature with an average error of 0.13 °C and 1.80 °C, respectively. Using the zero-dimensional model, the optimization of the PVT performance is achieved by choosing the optimal mass flow rate and inlet temperature for the system. For the experimental setup, a mass flow rate of 0.001 kg/s and an inlet temperature close to a relatively low ambient temperature provided the highest overall second law efficiency of 15.2%. The PVT system performs the best in regions with relatively low ambient temperature yet high solar radiation.