Journal of the Korean Solar Energy Society ISSN:1598-6411(Print) 2508-3562(Online) 한국태양에너지학회 논문집

Residential and commercial buildings often feature high window-to-wall ratios, leading to increased use of window-type BIPV systems for visibility and energy production. Unlike standard windows, window-type BIPV systems incorporate semi-transparent thin-film PV modules on the front, altering optical properties such as the Solar Heat Gain Coefficient (SHGC) and Visible Light Transmittance (VLT), as well as thermal insulation properties like overall thermal transmittance. Because the optical and thermal characteristics of windows affect building energy performance, it is crucial to analyze these characteristics in window-type BIPV systems and study their impact on energy performance. This study compares and analyzes the optical and thermal insulation characteristics of a window-type BIPV system with transmissive thin-film CIGS solar cells through simulations. These results are compared with those of general window systems to identify changes in energy performance when applied to residential buildings. The analysis shows that the thermal transmittance increased by 1.25% when PV modules were added to the general window system, while the SHGC decreased by 59.4% and the VLT decreased by 75.8%. Additionally, in buildings, annual heat gain through windows decreased by approximately 38%, resulting in a cooling load reduction of approximately 1.7% and a heating load increase of approximately 2%. Overall, the total energy load of the buildings increased. However, the total energy production of the building was approximately 27 kWh more than the total energy load due to energy production from PV power generation.