Development of a frameless building-integrated photovoltaic thermal system with phase change material

• A frameless building-integrated photovoltaic and thermal module was developed. • Thermal and electrical performance with phase change material was investigated. • Heat can be stored and collected without reducing power generation efficiency. • Winter experiments showed an average thermal efficiency of 15.7 % • Package reduced thermal efficiency by 14.2 % without degrading power generation. In this study, a frameless curtain wall-type building-integrated photovoltaic and thermal module is developed using phase change materials, and its thermal and electrical performance under outdoor conditions in winter is experimentally evaluated. Based on the applicability and constructability of vertical façades, microchannel heat pipes and manifolds for heat transfer are attached to the rear of a module, and a structure is designed to allow for the easy attachment and removal of phase-change materials. The experiment was conducted in three stages. In Test 1, the basic similarity in the power generation performance of two modules was verified. In Test 2, the thermal and electrical performances of the module were evaluated. In Test 3, the building-integrated photovoltaic and thermal module with phase change materials was compared with the module to which it was not applied to analyze the effectiveness of the phase change materials. In Tests 1 and 2, the average power generation efficiency was 11.4 % for Module (1) and 11.7 % for Module (2). In Test 3, both modules showed a power generation efficiency of 11.5 %, confirming that the application of PCM did not affect the electrical performance of the module. However, the thermal efficiency decreased by 14.2 % owing to the heat storage characteristic of the phase change material, and real-time heat recovery was limited during periods of high solar radiation. Thermal imaging analysis and time-of-day performance analysis confirmed that although the phase change materials effectively stabilized panel temperatures by suppressing temperature increase during the day and by releasing stored heat in the afternoon, it negatively affected the real-time thermal performance. This reduction in the thermal efficiency of the building-integrated photovoltaic and thermal module with phase change materials can be attributed to the method of attachment of the plastic-packaged phase change materials to the rear of the module, which resulted in an insufficient thermal storage performance. This study empirically clarified the trade-off between the electrical and thermal performances of a module with phase change materials, providing useful foundational data for establishing selective application strategies for phase change materials in the design of building-integrated renewable energy envelope systems.