Transpired opaque Solar Collectors (TSCs) have been often used in buildings (e.g. for direct heating of the outside air) due to their efficiency. In addition, one way to improve their efficiency is to integrate Phase Change Materials (PCMs). As a result, the goal of this study is to thoroughly investigate the behavior of TSCs with integrated PCMs in comparison with TSCs without PCMs. Therefore, based on an experimental approach carried out in the laboratory, we determined the performances of two TSCs (with lobed perforations) of around 2 m(2) each, one of them containing approximately 15.1 kg of organic PCM (commercial paraffin RT35). The data achieved show the superiority of the TSC with PCM: the maximum overall efficiency is improved by almost 6%; the maximum heating capacity is approximately 7.7% higher and during the cooling/PCM discharge period, the average heating capacity is over 5 times higher; more than 17% supplementary energy during the 9 h of operation; the average coefficient of performance is 16.4% higher; the "useful time of operation" is over 86% longer (meaning almost 4 h more). Consequently, the prototype of TSC with PCM analyzed in this study has led to promising results. Nevertheless, future work is required to improve the configuration of the TSC with PCM in order to enhance the interaction between the air within the TSC and the PCM. Moreover, the TSC with the PCM should be tested under real operating conditions (integrated in buildings) for longer periods of time.