Electrical-thermal-daylight analysis of an innovative semi-transparent photovoltaic curtain wall system integrated with a primary return air system in the heating season

Photovoltaic (PV) curtain walls (CW) offer significant potential for green buildings but face challenges such as suboptimal conversion efficiency, limited functionality, waste heat underutilization, and discomfort glare. To address these issues, this study presents a semi-transparent PV CW integrated with a primary return air system (RVPV-CW) for the heating season, combining solar energy generation with improved energy and daylight performance. A dynamic electrical-thermal-daylight model was developed to analyze and optimize its performance. Energy balance equations were solved iteratively using MATLAB. Air-conditioning devices were simulated using TRNSYS, and daylighting metrics were computed with DesignBuilder and Radiance. The RVPV-CW system demonstrated superior energy performance compared to a non-ventilated PV CW, reducing net energy consumption by 996.66 kWh (8.49 %) during the heating season. Return air ventilation enhanced electrical output by 14.36 kWh (0.87 %) and reduced air-conditioning energy use by 982.30 kWh (8.07 %) due to lower heating loads. The system also reduced artificial lighting use by 2508.11 kWh compared to an opaque CW, while maintaining Daylight Glare Probability (DGP) values below 40 %, effectively mitigating glare and ensuring uniform daylight distribution. These findings underscore the RVPV-CW's ability to enhance energy efficiency and visual comfort in building applications.