One of the biggest problems of generating electricity by photovoltaic panels is that about 80% of the incoming solar energy is transformed into heat. The heat causes the rise of operating temperature of the panel, thereby reducing its efficiency and performance characteristics. In this research, photovoltaic panel was passively cooled by means of aluminum heat sinks with different geometries in order to determine the enhancement of output character. One of the biggest problems of generating electricity by photovoltaic panels is that about 80% of the incoming solar energy is transformed into heat. The heat causes the rise of operating temperature of the panel, thereby reducing its efficiency and performance characteristics. In this research, photovoltaic panel was passively cooled by means of aluminum heat sinks with different geometries in order to determine the enhancement of output characteristics. Decrease in temperature by an average of 7.5 °C by means of heat sinks lead to increase in open-circuit voltage of 0.27 V, compared to the reference panel. Based on the experimentally obtained results, software was used to simulate the temperature and velocity fields for a string of three heat sinks, thus obtaining a better insight in heat transfer process of heat sinks. A polyhedral mesh and laminar fluid flow were applied for the simulation, leading to a good agreement between the experimentally obtained and simulated temperatures of the heat sinks, with average difference of about 1 °C. In order to determine the most efficient geometry of the heat sink for passive PV cooling applications, the data obtained by the experiment and simulation were numerically analyzed. The second heat sink, with its overall design (contact area with the panel, fin length, fin spacing), more effectively dissipates accumulated thermal energy to the surrounding air compared to the other two heat sinks. A model was developed to simulate the characteristics of a heat sink under various conditions using th. Photovoltaic panelTemperature reductionAluminum heat sinksSimulationPhotovoltaic conversion is currently considered as the most promising renewable energy technology for electricity generation, as a clean and sustainable energy source. It is not harmful to the environment; photovoltaic (PV) panels have a long lifetime and no associated CO2 emissions and low loss in transmission of electricity due associated to on site production,.Overheating of PV panels is a major obstacle to their operation, since just 1 °C increase of the silicon PV panel temperature leads to a 0.4–0.65% decrease in its efficiency,,. Ideally, the panel temperature should be maintained in accordance with standard test conditions, because high operating temperature has various unfavorable effects on the performance and lifetime of the PV panel,,. Excessive operating temperatures can decrease the power output of PV cells, whereas high levels of solar radiation have a positive impact on their performance, and therefore, it is important to maintain the operating temperature at the lowest possible value under high solar radiation. Hence, researchers are seeking for a suitable, low maintenance and inexpensive method to cool the PV panels of excessive heat,,,. There are two cooling techniques for PV panels, namely active cooling and passive cooling. With passive technique, which does not use electricity, it is possible to dissipate the heat from the photovoltaic panels to regulate their temperature a. The process of passive cooling involves transferring heat from the heat source, i.e. the PV panel, and dissipating it to the environment. Passive cooling techniques can be divided into three categories: passive air cooling, passive water cooling, and passive conductive cooling. In this paper, we will focus on passive air cooling, in particular the application of passive heat sinks.Heat sinks provide an uncomplex and inexpensive solution for cooling photovoltaic panels that require little or no maintenance and consume no-electricity. A heat sink is practically an element made of metal that is designed to enhance the transfer of heat from its source to the environment by means of natural or forced convection. Its main purpose is to augment contact area with the ambient air, for efficient heat dissipation. Natural convection occurs when cooling air flows through the fin array as a consequence of difference in pressure or temperature along the array. When observing the junction between the heat sink and the solar panel, there is a resistance to heat transfer that is caused by the presence of tiny air pockets between the joined surfaces, due to imperfections on the surfaces themselves. The pockets are filled with a material which improves interfacial contact by reducing thermal resistance such as thermal interface materials (TIMs).For. The experimental setup included two solar panels (LUXOR, LX −100 M/125–36) mounted on a metal structure at an optimal annual angle of 32° placed at the flat roof of the Faculty building shown in Fig. 2.One solar panel is considered referent (left one, Fig. 2) while the other (right one) was passively cooled by 36 heat sinks of different designs and sizes which were placed at the center of each solar cell (tedlar layer) as shown in Fig. 3.Aluminum heat sinks were chosen based on good heat capacity of the aluminum, good thermal conductivity leading to more efficient and rapid heat transfer to the environment. To obtain the good contact between the heat sinks and the back of the panel (tedlar layer) and to reduce thermal resistance between the two interfaces, thermal paste HY 510 was used. The edges of the heat sinks were glued with epoxy glue.The distribution of temperature of the both sides (front and rear side) of the panels and the heat sinks were taken by FLIR C5 thermal imaging camera (Fig. 4, Fig. 5). The accuracy of the camera is ±3°C within the measurement range from 0°C to 100°C.Experiment.
