Experimental and numerical assessment of the energy performance of a double-pass fan-assisted Trombe wall system that integrates photovoltaics

This study presents the results of an integrated methodological approach for experimental and simulation-based analysis of a building-integrated photovoltaic/Trombe wall (BiPV/T) façade module. The system passively harnesses solar radiation for the generation of thermal energy while producing renewable electricity. Moreover, the integration of photovoltaic panels behind glazed surfaces enhances the building aesthetics and increases its market appeal. An experimental campaign was conducted to evaluate the performance of a transparent surface of a module over different seasons. Temperatures and solar irradiance were monitored to assess the thermal and electrical efficiency. Additionally, a validated energy model was developed, using EnergyPlus, to simulate the annual energy production. The system achieved a measured winter daily thermal efficiency in Turin (IT) of about 14.8%. The PV panels exhibited an average electrical efficiency of ~6.5%. The use of translucent glass, which was selected for aesthetic integration purposes, reduced the transmitted solar radiation by 53%, thereby impacting the PV performance. Full-year simulations, which were conducted to explore alternative designs and operational strategies, provided further insights for optimisation of the system. The thermal efficiency of the simulated system ranged from ~15% to ~27% for the non-optimised and optimised designs, respectively. The avoided CO2 emissions ranged from 31.4 to 34.7 kgCO2eq/y. Overall, the BiPV/T façade module demonstrated a great potential as a sustainable building technology, together with energy efficiency and carbon reduction. The detailed description of the experimental setup provides a solid basis for system characterization, while the validated whole-system simulation enabled an effective assessment of its seasonal performance.