Circular Pathways for Photovoltaic Modules: A Second-life Assessment

Abstract

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.

Popular Abstract

Thousands of PV modules, also known as solar panels, installed during the early expansion of solar energy are now reaching the end of their warranty periods. Most are expected to be recycled in Europe. But what if many of them still work well enough to keep producing electricity for years?

This thesis explores whether aging solar panels can realistically be reused instead of directly recycled, under which conditions this may be possible, and what environmental impacts and benefits such an approach provide. While current European recycling practice mainly recovers materials such as glass and aluminium, reuse can preserve something far more valuable: the functioning solar panel itself. The study focused on first generation of solar panels and evaluated two end-of-life pathways: mechanical recycling and second-life reuse, while conducting a Life Cycle Assessment (LCA) to evaluate the environmental impacts of both scenarios.

The results show that reuse can considerably reduce environmental impacts by delaying the need to manufacture new solar panels. In other words, keeping a functioning panel in operation may save more resources than immediately breaking it down for material recovery. This challenges the common assumption that recycling is always the most suitable option for PV waste treatment.

At the same time, the study also shows that while reuse is not a straightforward solution, it can still be possible if supported by a proper framework. Ageing PV modules degrade differently depending on the affected layers, degradation mechanisms, operational history, and exposure to different weather conditions. Reliable testing is therefore essential before reuse can be considered both safe and practical. In addition, current regulations and waste management systems are still largely designed around treating PV modules as waste at the end of their life rather than as products with remaining functional value. This study therefore provides a framework for understanding under which conditions reuse may be possible and environmentally beneficial, as well as which technical aspects should be checked to make sure that reused PV modules remain safe and reliable.

The work highlights a broader challenge linked to the green transition: technologies designed to solve environmental problems can themselves create new waste streams. As solar energy continues to expand rapidly worldwide, decisions about what happens to aging panels will become increasingly important. The findings of this thesis suggest that future circular strategies for solar energy should not focus only on recycling materials, but also on extending the lifetime of products whenever possible.

• author: Jafar Salehi, Mahdi
• supervisor: Ilia Iarkov; Henrik Davidsson
• organization: Division of Energy and Building Design
• course: AEBM01 20261
• year: 2026
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Photovoltaic modules, PV reuse, Circular economy, PV recycling, Life cycle assessment (LCA), PV degradation
• language: English
• id: 9238148
• date added to LUP: 2026-06-15 13:08:59
• date last changed: 2026-06-15 13:14:13