Design, experimental testing, and numerical investigation of a ventilated semi-transparent photovoltaic facade integrated with supply-air conditioning in summer

Building-integrated photovoltaics (BIPV) still face numerous challenges, such as limited efficiency, inadequate utilization of waste heat, and high energy demand for air conditioning. To address these issues, this study proposes a ventilated semi-transparent double-skin photovoltaic façade (STPV-DSF) system coupled with air-conditioning supply air. A full-scale experimental platform was established, and comparative tests with an opaque PV façade (OPV) were conducted under typical summer conditions. Results indicate that the STPV facade achieved a 40.1% average thermal efficiency and a maximum heat recovery of 966 W, 36.6% higher than the OPV façade. A dynamic electrical and thermal coupling model was developed and validated in MATLAB. The model was validated against experimental data, with Cv(RMSE) values below 7%, confirming its accuracy. Parametric analysis shows that increasing the supply-air bypass ratio from 0.1 to 0.6 lowered PV temperatures and improved net energy gain by 18%. Southeast- and south-facing façades exhibited more balanced performance compared to other orientations. During system operation, PV efficiency improved, while indoor comfort remained acceptable (PMV -0.7 to 0.7; max PPD ≤11.42%). These results demonstrate the STPV-DSF system's potential for integrating BIPV and air conditioning systems and thereby support sustainable, energy-efficient building design.