Design, manufacturing, and performance of innovative aluminium-backed BIPV facade modules: a case-study in Germany

This paper presents the design, manufacturing, and performance analysis of novel aluminium-backed Building-Integrated Photovoltaic (BIPV) facade modules. A key innovation in the manufacturing process is the integration of a spacer layer that ensures electrical isolation between the aluminium backing and solar cells, maintaining compliance with safety standards. Laboratory characterization revealed a mean power output under Standard Test Conditions (STC) of 35 Wp per module and temperature coefficients of −0.368%/K for power. To account for the variable operating conditions in facade applications, the modules were also tested under different irradiance and temperature levels. Furthermore, their performance was evaluated under various electrical configurations and partial shading scenarios to assess the impact of shading and the effectiveness of mitigation strategies. Series configurations with bypass diodes reduced additional shading losses from 65% to 8% in long side shading scenarios. Parallel configurations demonstrated the highest shading resistance but suffered from reduced power output due to increased currents (increase of I²-resistive losses). Beyond laboratory testing, real-world performance was assessed using a custom-designed substructure that enabled vertical mounting in all cardinal directions (North, East, West, and South), with each orientation represented by a series of four modules (135Wp per orientation). This setup facilitated simultaneous measurement of irradiance, temperature, and I-V curve parameters, allowing for a comprehensive comparison of energy yields across orientations. The results highlight the benefits of not only south-facing facades but also east-, west-, and even north-facing installations. Furthermore, PVSyst simulations incorporating laboratory findings were conducted to estimate annual energy yields across different geographic locations. For the test site in Halle (Saale), the simulated yearly energy yield ranged from 42.4 kWh for the north-facing facade to 107.3 kWh for the south-facing facade, based on the installed capacity of 135 Wp per orientation. Additional simulations for other climatic regions confirmed the general trends, while highlighting variations in absolute yield depending on local irradiation conditions. The findings demonstrate that multi-directional solar harvesting leads to a more balanced distribution of energy generation throughout the day and across seasons. This study underscores the potential of aluminium-backed BIPV facade modules to enhance sustainable energy production in urban environments, showcasing their viability as an efficient and adaptable solution for building-integrated solar applications.