A combined thermal and electrical performance evaluation of low concentration photovoltaic systems

Abstract

Due to the expectations of improving the overall efficiency of photovoltaic installation, the increase solar irradiation that could be converted into electricity should be considered as an alternative solution for existing PV technologies. Low-concentration photovoltaic systems such as reflective surfaces or Fresnel micro lens plates were chosen for this study because they were economically justified and easy to install and maintain. The low concentration systems were studied theoretically and experimentally under sunny and cloudy weather conditions. After the initial optimization of the system geometry and construction, both electrical and thermal performances were evaluated and compared with a reference PV panel. In addition, the effect of additional irradiation as well as panel temperature was studied for a specific period using thermography and digital image techniques. It was revealed that the highest improvement in energy performance was achieved by the panel with reflective surfaces, while the Fresnel plate considered here slightly decreased this performance in comparison with the reference case. The consideration ends with an economic analysis of both systems in the case of free-standing PV installation and a list of recommendations are presented, based on the empirical results. The highest improvement of energy performance can be achieved by the implementation of reflective surfaces, about 20% of the average daily global efficiency, and 15% on electrical production. In the case of the Fresnel micro lens, a decrease in both global efficiency and electricity production is observed, 8% and 21%, respectively. Regarding the temperature of PV panels, significant overheating was not registered; about 45–55 °C for the entire experimental test.