Search

The photovoltaic (PV) industry is reaching an inflection point to become a major source of energy. Last decades brought important technical progression in modules' yield and durability. Already available technical solutions might reach the highest power output and the lowest environmental impact in a module. Nevertheless, cost remains the major driver for innovation; top PV panels must combine cost/delay/yield to reach reasonable market share. Our paper presents the development of silicon heterojunction (SHJ) modules with exemplary power and reliability with significantly reduced environmental impact and components sourced from Europe. In order to guide the technology choice in the design phase, we performed a Life Cycle Assessment (LCA) sensitivity study. For a standard PV module, we identify the main steps to improve in order to reduce its environmental footprint. This guided us to tackle the components with the highest impact on the carbon footprint, namely the wafer, glass front sheet and aluminium frame. The proposed improvements will be tested from technical and economic point of view and assembled within one PV module. At the cell scale, we achieved the reduction of the carbon footprint by reducing the thickness of the wafers issued from the European value chain. Optimisation of metallisation and cell interconnection has limited the consumption of silver (Ag), a critical raw metal. At the module level, we implemented the reduction of glass thickness and the replacement of the aluminium frame with a natural fibre‐based frame in a glass‐backsheet module configuration. In addition, we applied a 'design for recycling' approach for the choice of encapsulant and backsheet. The combination of these innovations led us to the realisation of a 566‐Wp recyclable module using a tiling interconnection, cells with an average efficiency of 22.57% with a carbon footprint of 313 kgCO2eq/kWp. Highlights: Presenting a design for the environment approach from conception to realisation of industrial‐scale prototype with the technical challenges of combining multiple technical and material innovations.Combination of SHJ cell on thin wafers < 120 μm with reduced Ag. In content has been implemented on low carbon wafers sourced in the European Union (EU).Paving interconnection using electrically conductive adhesive (ECA) based on low temperature and Pb‐free interconnection technology, with reduced Ag content.Case study of low carbon frame: implementation of natural fibre (timber) frame and its initial reliability study is novelty in the field.On module level, the bill‐of‐material (BOM) selection with design for recycle motivated the choice of thermoplastic encapsulant, fluorine‐free backsheet and thin front glass. [ABSTRACT FROM AUTHOR]

Assessment of the critical nature of a material for an application is a relevant notion to anticipate supply issues for an application and a territory. To establish a list of the critical materials, we have developed an approach taking into account geological scarcity, deployment logistics and societal aspects. This article aims to apply this framework to photovoltaic (PV) module interconnection. We draw the conclusion that even if concerns of critical materials are focused on Silver (Ag) scarcity (on metallization part), interconnection materials such as Tin (Sn) and Bismuth (Bi) are even more critical, mainly due to their mostly dispersive uses. This leads us to a standard module conception analysis and emphasizes the interest of improving a more modularized PV module architecture in order to improve high value recycling. An example of such a conception is given with NICE concept. Another example offering a way to optimize metallization conception toward a less consuming pattern is also described.

Since massive numbers of photovoltaic (PV) modules are expected to be discarded in the next decades, it is important to think about end‐of‐life management for those PV modules and to include re‐use next to recycling. However, the re‐use of decommissioned PV modules is a quite complex subject since there are requirements from technical, economic, environmental and legislative point of view. An evaluation of possible applications for second‐hand PV modules showed that currently, the use of these PV modules in high‐income countries is only interesting for specific applications. These are the replacement of some defect modules to repair PV systems (that usually still receive feed‐in tariff) or the replacement of all PV modules for either a low‐cost extension of system lifetime or the repowering of severely underperforming systems. For low‐income countries, second‐hand PV modules are interesting to build new small to medium size PV systems (often off‐grid). The typical decommissioned PV module is a crystalline silicon glass‐backsheet module from a utility power plant. Most PV modules originate from plants that have been partly damaged by severe weather or from repowered plants that did not receive feed‐in tariff (anymore). Currently, technical requirements to qualify potentially re‐usable PV modules for re‐use are lacking. In the legislation also, a clear criterion for a PV module to be considered functional is needed, since it is not an easy yes/no situation like for a typical electronic device. In this paper, guidelines for a low‐cost quality inspection and cost‐effective PV module repair are given. It is proposed to set a clear performance threshold at 70% of the original power for a PV module to be not considered as waste. With this paper, we aim to open the dialogue on a commonly accepted re‐certification protocol and threshold values. Currently, the worldwide re‐use market size is estimated to be around 1 GWp/year, of which 0.3 GWp/year is originating from Europe (mainly Germany, with Italy rapidly coming up). Many second‐hand PV modules are shipped to developing countries without recycling facilities which might create the risk of disposal on the longer term. To create a healthy and sustainable market for second‐hand PV modules, it will be important that evaluation standards for potentially re‐usable PV modules become available and that the existing electronic waste legislation will be adapted for energy‐generating products like PV modules. [ABSTRACT FROM AUTHOR]

Low-temperature interconnection processes for high-efficiency PV cells will be a key R&D topic in the coming years. In reality, to avoid significant deterioration of the surface passivation, the metallization and interconnection processes of silicon heterojunction (SHJ) cells are limited to temperatures below 200°C; tandem cells with a perovskite subcell demand an even greater reduction in process temperature, namely below 130°C. Moreover, to ensure the sustainability of PV production on a TW scale, the use of scarce materials, especially silver, needs to be reduced, as 10% of the world's supply was already dedicated to PV in 2020. This paper addresses the results obtained in terms of reducing the silver consumption in interconnection technology based on electrical conductive adhesive (ECA) and Pb-free ribbons. The first demonstration of stencil-printing-based ECA deposition with an improved accuracy using equipment from Mondragon Assembly is reported. This equipment allows a minimal amount of ECA deposition while maintaining highly reproducible results, as demonstrated through the fabrication of 400 glass-glass modules and the validation of process reliability. This paves the way towards creating Si/perovskite tandems that involve ECA curing at temperatures below 130°C with sufficient adhesion (> 0.8N/mm) of the ribbon to the cell, as well as offering a means to consistently reduce Ag usage. Furthermore, improvements to the Mondragon Assembly stringer to handle next-generation cells are outlined. [ABSTRACT FROM AUTHOR]