500x CPV Receiver with Integrated Micro-Finned Heat Sink

Abstract

Introduction The main aim of concentrating photovoltaics (CPV) is reducing the amount of the expensive semicondutive material by replacing part of it with a reflecting optics and, thus, increasing the density of the sunlight hitting a smaller cell. Cell’s temperature need to be minimized in order to enhance the electrical efficiency, to limit the thermal stresses, and to avoid damages. Common flat photovoltaic modules usually operates without cooling systems, whereas cooling is generally needed for concentrating photovoltaics, to manage the heat generated by concentrating the sunlight. The low operating temperature is not the only achievement that a CPV cooling system needs to meet. The uniformity of the temperature has to be considered, both at single cell’s and at series-connected cells’ levels. Temperature gradients across the cell are generally due to non-uniform illumination on the active area, and cause power losses and may lead to the damages [1]. Series-connected cells working at different temperatures generate different currents: the overall series current is limited by the less performing cell. An optimal CPV cooling system should prevent the system from the occurrence of current-mismatch due to non-uniform temperature. Moreover, the cooler is generally required to be simple, in order to grant high reliability and not to strongly affect the CPV plant cost. A reliable system is essential: any failure could cause damages to the cells and long stops in the power generation. Nowadays, fins are commonly used in many passively-cooled CPV installations [2,3]. The development of micro- and nano-technologies offers new perspectives for both active and passive CPV cooling. Among all the possible solutions, a micro-fin array offers a simple, suitable solution for improving a passive cooling system [4]. In the present article, the first investigation on the thermal performance of a 500x CPV receiver equipped with a micro-fins array is presented.