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]

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]

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]

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]