Wooden Photovoltaic Module Frames : Proof of Concept, Life Cycle Assessment and Cost Analysis

Sammanfattning: To mitigate climate change and to achieve global carbon neutrality, the expansion of renewable energy sources is of paramount importance. In this context, photovoltaics (PV) are widely regarded as one of the most promising technologies to lead the transformation towards decarbonized energy systems. However, the manufacturing of PV systems is associated with initial greenhouse gas emissions linked to the procurement of PV components. Therefore, current research focuses on minimizing initial emissions to improve the overall environmental performance of PV systems. Since previous research suggests that conventional aluminum module frames contain a significant amount of embodied carbon, this study investigates a possible material substitution with wood as alternative frame material to lower the overall carbon footprint of PV modules.  To test the technical feasibility of PV modules with wooden frames, a proof of concept (POC) is conducted using wood types that exhibit necessary characteristics regarding their mechanical properties and durability. Guided by the finite element method and preliminary testing, a novel frame design is conceived, and PV modules with wooden frames are realized. The prototypes are put to extensive testing, in which the mechanical stability is examined, and weathering effects are investigated in an outdoor installation. Furthermore, a life cycle assessment (LCA) is carried out to quantify potential benefits of wooden compared to aluminum frames regarding their global warming potential and other environmental impact categories. Lastly, this study compares the economic performance of wooden PV module frames with aluminum frames and considers possible optimizations in the value chain of wooden frames. POC results show that PV modules with wooden frames - in line with industrial standards - are feasible, yet mechanical stability and durability vary depending on the type of wood and overall design. LCA results suggest that wooden frames exhibit invariably better environmental performance in all impact categories although a reduced module lifetime may impair the overall life cycle performance. In regard to cost efficiency, wooden frames are more costly than aluminum frames, yet financial incentives or subsidies may make low-carbon materials more competitive in the future. It can be concluded that wooden PV module frames may be a promising alternative to standard aluminum frames provided that the overall lifetime is identical. Thus, additional studies are required to analyze the long-term performance and to identify areas of application for modules with wooden frames, for instance in the building-integrated PV sector. Lastly, further research is needed to explore additional utilizations of wood in PV systems such as in ground and roof mounting structures.