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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]

On-board photovoltaic (PV) energy generation is starting to be deployed in a variety of vehicles while still discussing its benefits. Integration requirements vary greatly for the different vehicles. Numerous types of PV cells and modules technologies are ready or under development to meet the challenges of this demanding sector. A comprehensive review of fast-changing vehicle-integrated photovoltaic (VIPV) products and lightweight PV cell and module technologies adapted for integration into electric vehicles (EVs) is presented in this paper. The number of VIPV projects and/or products is on a steady rise, especially car-based PV integration. Our analysis differentiates projects according to their development stage and technical solutions. The advantages and drawbacks of various PV cell and module technologies are discussed, in addition to recommendations for wide-scale deployment of the technologies. [ABSTRACT FROM AUTHOR]

This article reports on the 11th Workshop on Metallization and Interconnection for Crystalline Silicon Solar Cells, which took place in May 2023 in Neuchâtel, Switzerland. An important observation at the workshop was that, while screen printing is still dominating metallization, alternative pastes with increasing Cu content are starting to be implemented in the industry in response to the need to decrease cost and improve sustainability. Compared to previous workshops, interconnection topics were more prevalent in this edition because of the need for interconnection solutions that work at lower temperatures, as is needed for emerging solar cell technologies. Electrically conductive adhesives (ECA) have gained in importance in this respect. Understanding of reliability aspects and insight into proper characterization of ECAs are increasing, yet the challenge is here is to substantially further reduce cost and silver content. [ABSTRACT FROM AUTHOR]

Recent research has shown that bifacial PV modules with a glass/glass packaging are prone to different PID mechanisms occurring simultaneously on the front and the rear side of the solar cell. With this in mind, researchers investigating the impact of PID on each side of the bifacial solar cell separately apply PID stress to one side of bifacial PV modules according to stress method (b) as described in the IEC TS 62804‐1, that is, contacting the surface with a conductive electrode. Yet, in this paper, we show that such practice of PID testing might result in an unintended development of an electric field between the environmental chamber and the nonstressed side of the solar cell. Through our experimental study, we reveal that this electric field results in unintended bifacial PID stress of bifacial solar cells, which goes along with misleading interpretations of the evolving PID mechanisms and susceptibility of bifacial PV modules. Next to the methodology concerns, we discuss three possible solutions to prevent such unintended PID mechanisms from occurring. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) waste, associated to the exponentially growing PV installations on global scale, presents today an emerging environmental challenge but also brings unprecedented and multifold value creation opportunities. In this context, significant PV business and research and development (R&D) efforts shift towards establishing a more sustainable, environmentally friendly and economically viable end‐of‐life (EoL) management for PV modules: including recycling, recovery of raw materials, repair/refurbishment and even re‐use of decommissioned or failed PV modules. In the CIRCUSOL project, PV partners aspire to formalize the repair/refurbish and re‐use value chains in the PV industry and propose a circular business model, based on a product‐service system (PSS). Towards these goals, this review study introduces the relevant research groundwork, a status overview and today's R&D and business challenges in PV recycling, repair/refurbishment and re‐certification aspects for second‐life PV modules. The topics and the relevant reported literature are examined from both circular economy and technology perspective. The review indicates a considerable technological and operational know‐how in PV EoL management that already exists and continuously evolves in mature PV markets. On the other hand, R&D in repair/refurbishment of decommissioned and/or failed PV modules remains scarce, and best practices and commercial services for reliability testing/re‐certification and trading of second‐life PV modules are neither standardized nor consolidated into any PSS or business model. [ABSTRACT FROM AUTHOR]

This paper reports on a novel and highly innovative technology to interconnect back-contact cells. First, a background section explains the currently developed interconnection technologies. Then, our novel concept is introduced: interconnection of the cells is achieved with a woven fabric, combining both conductive wires, needed for the interconnection, and insulating wires, crucial to avoid shunting between both polarities at the backside of the cell. Weaving also allows out-of-plane stress relief features. In the third section, we explain that our technology combines the advantages of multi-wire interconnection such as low-stress and reduced resistive losses with known and low-cost materials of traditional module assembly. Additional to previous publications, we demonstrate that the technology can be tuned broadly in terms of costs and resistive losses using an optimized interconnection pattern. These resistive loss simulations are also validated with the measured additional resistance in IBC test samples. We also present a preliminary thermal cycling test with promising results. Finally, first functional demonstrators IBC cells are fabricated, disclosing the process flow and initial technology developments. These results clearly demonstrate the proof-of-concept of the woven interconnection fabric, and based on electrical characterization we provide suggestions for improvements. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We report on the degradation of organic photovoltaic (OPV) cells in both indoor and outdoor environments. Eight different research groups contributed state of the art OPV cells to be studied at Pomona College. Power conversion efficiency and fill factor were determined from IV curves collected at regular intervals over six to eight months. Similarly prepared devices were measured indoors, outdoors, and after dark storage. Device architectures are compared. Cells kept indoors performed better than outdoors due to the lack of temperature and humidity extremes. Encapsulated cells performed better due to the minimal oxidation. Some devices showed steady aging but many failed catastrophically due to corrosion of electrodes not active device layers. Degradation of cells kept in dark storage was minimal over periods up to one year. [ABSTRACT FROM AUTHOR]

Although degradation mechanisms in organic photovoltaic devices continue to receive increased attention, it is only recently that the initial light-induced failure, or so-called burn-in effect, has been considered. Both prototypical polythiophene:fullerene and polycarbazole:fullerene systems exhibit an exponential performance loss of ≈40% upon 150 h of continuous solar illumination. While the decrease in both the short-circuit current ( JSC) and open-circuit voltage ( VOC) is the origin of performance loss in poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PC60BM), in poly(N-9′-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)):[6,6]-phenyl-C71-butyric acid methyl ester (PCDTBT:PC70BM) the decline of the fill factor dominates. By systematic variation of the interface layers, active layer thickness, and acceptor in polythiophene:fullerene cells, the loss in JSC is ascribed to a degradation in the bulk of the P3HT:PC60BM, while the drop in VOC is reversible and arises from charge trapping at the contact interfaces. By replacing the C60 fullerene derivative with a C70 derivative, or by modifying the electron transport layer, the JSC or VOC, respectively, are stabilized. These insights prove that the burn-in process stems from multiple concurrent failure mechanisms. Comparing the ageing and recovery processes in P3HT and PCDTBT blends results in the conclusion that their interface failures differ in nature and that burn-in is a material dependent, rather than an intrinsic, failure mechanism. [ABSTRACT FROM AUTHOR]

A series of electron-deficient truxenone derivatives are investigated as fullerene alternatives in organic photovoltaic applications. These new electron-accepting molecules have easily tunable absorption profiles, more than ten-fold higher absorptivities than PCBM, slightly higher electron affinities than PCBM and clearly defined and highly reversible reductive characteristics. Fabrication of efficient bilayer solar cells with a subphthalocyanine (SubPc) donor illustrates the promise of this class of materials as electron acceptors in organic solar cells. [ABSTRACT FROM AUTHOR]

The highly conductive polymer PEDOT:PSS is a widely used hole transport layer and transparent electrode in organic electronic devices. To date, the mechanical and fracture properties of this conductive polymer layer are not well understood. Notably, the decohesion rate of the PEDOT:PSS layer and its sensitivity to moist environments has not been reported, which is central in determining the lifetimes of organic electronic devices. Here, it is demonstrated that the decohesion rate is highly sensitive to the ambient moisture content, temperature, and mechanical stress. The kinetic mechanisms are elucidated using atomistic bond rupture models and the decohesion process is shown to be facilitated by a chemical reaction between water molecules from the environment and strained hydrogen bonds. Hydrogen bonds are the predominant bonding mechanism between individual PEDOT:PSS grains within the layer and cause a significant loss in cohesion when they are broken. Understanding the decohesion kinetics and mechanisms in these films is essential for the mechanical integrity of devices containing PEDOT:PSS layers and yields general guidelines for the design of more reliable organic electronic devices. [ABSTRACT FROM AUTHOR]

We report the application of novel mono- and bis-o-quino-dimethane C60(oQDMC60) adducts in bulk heterojunction photovoltaic devices. When blended with poly(3-hexylthiophene), the fullerene adducts presented here have an enhanced open-circuit voltage of 640 mV and 820 mV, while preserving high short-circuit current and fill factor, resulting in efficiencies of 4.1% and 5.2%, respectively. Detailed assessment of material properties relevant to photovoltaic devices such as energy levels, charge carrier mobility, absorption and solubility further complements the evaluation. Increased fullerene solubility hindering phase segregation in blends with bis-oQDMC60has been circumvented by an in-depth morphology optimization assisted by absorption spectroscopy, X-ray reflectivity and atomic force microscopy. This optimized preparation could also serve as a guide for implementation of similar fullerene derivatives. Furthermore, we compare bis-oQDMC60to previously reported fullerene bis-adducts to provide insight into this emerging class of materials. [ABSTRACT FROM AUTHOR]

The cover image, by Tom Borgers et al., is based on the EU PVSEC Paper A woven fabric for interconnecting back‐contact solar cells, DOI 10.1002/pip.2851. [ABSTRACT FROM AUTHOR]

Stability studies of organic solar cells have recently revealed an initial light‐induced burn‐in process that calls into question the intrinsic stability of these devices. In article number 1400848, Eszter Voroshazi and co‐workers demonstrate that multiple concurrent failure mechanisms occur during the burn‐in, indicating that burn‐in is not intrinsic, but rather material dependent. This understanding allows the proposing of mitigation routes that are tested with the aim of solving this recognized issue. [ABSTRACT FROM AUTHOR]