The Effect of Adding Paraffin Wax to PVT Collector on Its Efficiency: A Practical Study

Abstract

The efficiency of a PV plate is not more than 20% depending on its type, because more than 80% of the solar radiation falling on the PV panel is not converted into useful energy. In order to increase the PV efficiency, several studies have been conducted to convert it to a hybrid PVT system by adding a heat exchanger to its back surface. The present study involves a comparison of the thermal performance between a conventional PVT and a modified PVT collector containing a layer of paraffin wax on the heat exchanger. An experimental platform was established in the Iraqi city of Kirkuk (latitude 35.467 north and longitude 44.38 east) and experiments were conducted in February 2020 in two parts. The first part is an experiment without water circulation and the second part involves water circulation at a constant flow rate of 1 LPM. In the first part, the experiment result showed that paraffin wax caused a decrease in the electrical efficiency of the PV panel by 5.3% due to the temperature rise of the surface of the photovoltaic plate. On the other hand, the result of the second part of this study showed that the use of paraffin wax has an advantage in improving the total efficiency of the hybrid MPVT system, as it maintains its thermal efficiency of over 60% in periods after 12:00 p.m. as a result of storing thermal energy in the wax layer. Also, two mathematical relations were obtained that express the instantaneous efficiency for each collector.