Tunnel-oxide passivated back-contact (TBC) solar cells combine TOPCon-type passivating contacts with an interdigitated rear-contact architecture. Their efficiency is controlled by mutually coupled optical absorption, lateral transport, and recombination losses in the rear p-type and n-type poly-Si contacts. In this work, Quokka3 was used as a three-dimensional device-level sensitivity tool constrained by a production-line reference device, wavelength-dependent optical-generation profiles, electrochemical capacitance-voltage (ECV) active-doping measurements, and factory process windows. The purpose of the simulations was not to reproduce every production batch, but to separate loss mechanisms that cannot be independently varied in finished cells. Thickness scans show that parasitic absorption in n-type poly-Si is the dominant thickness-related limitation to J sc , whereas p-type poly-Si exhibits a broader trade-off between optical loss and metal-contact shielding. With p-type poly-Si at Rsheet = 100 Ohm sq −1 and n-type poly-Si fixed at 3 × 10 20 cm −3 and 340 nm, the preferred p-type active-doping range is 4 × 10 19 –6 × 10 19 cm −3 , giving simulated efficiencies of 27.109–27.112% under the stated boundary conditions. Increasing n-type poly-Si doping progressively reduces J sc through free-carrier absorption and Auger recombination unless the loss is compensated by lower contact resistance. ECV confirms a pronounced boron diffusion tail in p-type poly-Si and a box-like phosphorus profile in n-type poly-Si, providing material-level constraints for the simulation inputs. Production data provide trend-level validation: stable p-type poly-Si processing occurs near 290–300 nm and 115–135 Ohm sq −1 , whereas an n-type poly-Si layer of approximately 340 nm and 27 Ohm sq −1 remains the robust industrial condition. The study therefore presents the Quokka3 results as experimentally constrained process guidance and identifies which predictions still require targeted production-line validation.
Silicon heterojunction (SHJ) module technology presents certain challenges, notably the degradation of the indium tin oxide (ITO) layer, a key component of SHJ cells, due to moisture ingress into the module, which leads to sodium ion penetration. The impact of these degradation pathways is typically assessed using DH (Damp Heat) and PID (Potential Induced Degradation) testing protocols, which effectively simulate and measure the effects of sodium diffusion and migration. This study investigates strategies for reducing SHJ cell sensitivity to sodium penetration by modifying the ITO layer. One strategy is to reduce the thickness of the ITO layer and partially replace it with alternative capping layers, such as SiO or SiN. This approach has the advantage of limiting ITO consumption. The second approach focuses on modifying the source of sodium in the PV module: the glass. Several glass types, including soda-lime, borosilicate, and aluminoborosilicate were tested for their sodium content and associated degradation behavior. Borosilicate and aluminoborosilicate modules exhibited minimal degradation. These results reveal new perspectives for improving the PID resistance of SHJ modules, and both routes appear promising for producing robust SHJ modules under high system voltages.
This paper introduces the product–level circularity metric (PLCM) as a practical tool to assess the circularity of integrated photovoltaic (PV) elements. The PLCM, originally proposed by Linder et al., quantifies product circularity by comparing the economic value of reused, recycled, or repurposed components to the total value of the product. By focusing on economic value rather than mass or energy, the PLCM offers actionable insights for manufacturers, designers, and policymakers, highlighting opportunities to enhance resource efficiency, reduce material dependency, and support circular design strategies. To demonstrate its applicability, we adapted the PLCM methodology for PV products and developed an Excel–based tool to facilitate its use. Three illustrative case studies are presented: a building-integrated-PV roof tile with embedded flexible thin-film solar cells, a conventional crystalline-silicon module, and a glass–glass perovskite module. These examples show how components with higher economic value can strongly influence the overall circularity score and how PLCM can guide design–for–circularity decisions. In the perovskite module case, a scenario–based sensitivity analysis further highlights how different assumptions on material recirculation and design choices can meaningfully shift the resulting circularity assessment, offering valuable insights for prospective technology development. While the metric does not account for energy consumption or end–of–life recyclability, it complements existing sustainability indicators such as life cycle assessment (LCA). Used together, PLCM and LCA provide a more holistic view of product sustainability. This paper underscores the PLCM’s potential to advance circular–economy principles in the PV industry and to support transparent, design–oriented evaluation of material choices and product architectures.
This work presents a numerical study of two passive cooling strategies for photovoltaic (PV) modules using recycled materials. The main goal is to limit the performance losses caused by high operating temperatures under real outdoor conditions, which differ significantly from Standard Test Conditions (STC), and to improve the overall electrical efficiency. The analysis is performed using three-dimensional transient simulations in COMSOL Multiphysics, coupling heat transfer and fluid flow in solid and porous domains. In the first configuration, a recycled polyurethane (PU) foam layer saturated with water is applied at the rear of the PV module to enhance heat dissipation through coupled heat and moisture transport within the porous structure, including evaporative cooling effects. The second configuration uses aluminum fins attached to the rear surface of the module, increasing the heat exchange area and strengthening natural convection with ambient air. The results show that the PU foam and aluminum fin systems reduce the average operating temperature by 16.4 °C and 9.8 °C, respectively, compared with the reference module. These reductions translate into relative electrical efficiency improvements of 8.49% and 5.10%, confirming the effectiveness of both passive cooling approaches under the studied conditions.
