Circular Pathways for Photovoltaic Modules: A Second-life Assessment

Sammanfattning

The rapid growth of photovoltaic (PV) deployment has raised concerns about the management of end-of-life PV modules, particularly crystalline silicon (c-Si) technologies approaching the end of their service life. Although PV systems contribute to renewable electricity generation, the increasing number of ageing modules poses environmental, technical, and resource-related challenges regarding whether these modules should be reused or recycled. Since PV modules contain valuable materials, including classified critical raw materials under current regulations, circular end-of-life management requires greater focus. At the same time, the global PV supply chain remains dependent on energy-intensive manufacturing processes, raw material extraction, and geographically concentrated production, raising concerns about supply chain vulnerabilities and material security. This study investigates reuse and recycling as two circular end-of-life pathways for first-generation PV modules in a Nordic climate context. Reuse criteria were established based on degradation science, field data and safety considerations, while a Life Cycle Assessment (LCA) was conducted in SimaPro using the Ecoinvent database in alignment with EN 15804+A2 and ISO standards. Due to the absence of an established LCA framework for PV module reuse, the study adapted the EN 15804 principles of polluter pays, end-of-waste state, functional equivalence, and substitution, to assess the reuse scenario. The results of this study revealed that PV modules operating in cold climates generally degrade more slowly than those in other climates. Field evidence further suggests that many PV modules removed early from service still retain functional value and may qualify for second-life use. However, reliable reuse depends on structured testing capable of detecting safety-critical defects, and degradation mechanisms that may remain latent during operation but become important as modules approach the later stages of their service life. The LCA results further show that the production stage dominates life cycle environmental impacts, accounting for approximately 90% of total emissions in both scenarios. Within this stage, the solar cell layer represents only 4% of module mass yet contributes 79% of production emissions, meaning that each 1% share of module mass associated with the solar cell corresponds to nearly 20% of production emissions. Glass and aluminium together make up 83% of module mass but account for only 13% of production emissions. Mechanical recycling targets these heavy and low-impact fractions, while the solar cell that carries the largest environmental footprint remains unrecovered. This mass-impact inversion is precisely what reuse addresses by extending the lifetime of functional PV modules, while recycling remains an important pathway for modules that can no longer be effectively reused. The study concludes that reuse is not simply an environmental preference but a technically achievable pathway, as demonstrated by the reuse criteria established in this study based on degradation science and structured testing. However, the methodological and regulatory frameworks needed to support this at scale, such as standardised testing protocols, agreed performance thresholds, and economic incentives do not yet exist, and their absence is what prevents the circular potential identified in this study from being realised in practice.