Towards Circular Solar Technologies: Novel Bio-Based Polymers as Next Generation Encapsulants

Conventional photovoltaic (PV) encapsulants such as ethylene-vinyl acetate (EVA) suffer from yellowing, delamination, irreversible crosslinking, and poor recyclability, limiting module lifetimes and sustainability. To enable a circular economy (CE) for PV modules, new encapsulants must combine long-term stability with programmed end-of-life (EoL) pathways. This review critically evaluates recent progress in bio-based polymers synthesized via ring-opening metathesis polymerization (ROMP) and alternating ROMP (AROMP) as candidates for next-generation encapsulants. Compared to EVA, these systems offer modular design flexibility, renewable feedstock origins, and recyclability potential. Key challenges remain, including long-term UV and moisture stability, lack of standardized testing, and limited scalability. Future work should prioritize in situ aging, quantitative benchmarking of barriers and optical properties, and module-level validation. Building on these insights, we outline design principles for circular encapsulants: thermomechanical tuning via modular monomers, incorporation of aromatic blocks for UV stability, and degradable motifs as “molecular fuses” to reconcile durability with recyclability. This study emphasizes catalyst footprint minimization, continuous-flow synthesis for scalability, and standardized durability testing. By integrating renewable precursors (aromatics, furans, saccharides) with precision polymerization, a pathway toward closed-loop PV encapsulants that combine reliable performance with sustainable EoL recovery is presented.