The present experimental study focuses on the passive thermal regulation of electronic devices and concentrator photovoltaic (CPV) systems using phase change material (PCM). Therefore, a fabricated system was attached to a silicon rubber heater to imitate the heat dissipation from electronic devices or CPV cells. Several sets of experiments were performed to investigate the melting of three different PCMs (RT25HC, RT35HC, and RT44HC) at three distinct heat flux values of 2000, 2950, 3750 W/m(2). Results revealed that using RT25HC, RT35HC, and RT44HC PCMs decreased the average front wall temperature associated with the electronic component or CPV cells by about 69.8, 80.44, and 74.44 degrees C when compared to that of the system without PCM. The solidification of RT44HC PCM was studied at different ambient temperatures of 20, 25, and 30 degrees C. It was noticed that, the time to reach the complete solid phase increases from 407 min to 501, and 585 min when the ambient temperature rises from 20 to 25, and 30 degrees C, respectively. Finally, the effect of cavity formation inside solid PCMs due to solidification shrinkage on their cooling performance was investigated. Results indicated that air cavities formation inside solid PCMs has insignificant effect on their cooling performance. (C) 2019 Elsevier Ltd. All rights reserved.