Progress in Photovoltaics最新文献

Daylight photoluminescence imaging of crystalline silicon photovoltaic modules is demonstrated for modules embedded in rooftop and utility-scale systems, using inverters to electrically switch the operating point of the array. The method enables rapid and high-quality luminescence image acquisition during the day, unlocking efficient performance and quality monitoring without the need to connect specific electrical hardware or to make any modifications to the system wiring. The principle of the measurement approach is discussed, and experimental results from a 12-kW_DC residential rooftop system and from a 149 MW_DC utility-scale photovoltaic power plant are presented. Measurements were performed using commercial inverters without modifications to the inverter hardware or firmware. In the case of the utility-scale power plant, the daylight photoluminescence image acquisition of modules connected to a central inverter was obtained from a remote piloted aircraft. Data analysis includes the conversion of photoluminescence image data into implied voltage differences.

The optimization of III-V-based photovoltaic cells involves addressing the trade-off between optical losses due to grid shading and electrical losses due to series resistance. In this work, we overcome the boundary conditions of this optimization problem by increasing the grid line height. Contrary to a few micrometer high evaporated metal grid lines, distributed circuit modeling of 1-cm² GaAs photonic power converters suggests that 15-μm high grid lines yield the best performances, especially for high-current operation in the 1 to 10 A cm⁻² range. We have successfully implemented a silver plating process into the fabrication scheme of these devices. Current–voltage measurements under intense illumination demonstrate fill factors above 80% at currents up to 35.8 A, highlighting the capability to extract such high currents without major series resistance losses. Under equivalent monochromatic input power of 62.6 W, this results in a maximum power output of 35.5 W from the 1-cm² single-junction photovoltaic cell. This development enables optical power links with largely increased power densities, reducing the material demand of precious semiconductors and associated costs.

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.

The delamination of encapsulants in photovoltaic (PV) modules is a common issue that leads to power loss due to optical losses. Encapsulant debonding is usually examined under monotonic loading conditions subsequent to environmental exposure such as damp heat. Service-relevant, superimposed environmental-mechanical fatigue loads are not considered adequately. Hence, the environmental fatigue delamination resistance of thermally toughened double glass laminates with an ethylene vinyl acetate copolymer (EVA) adhesive layer was investigated in this study. Focus was given to the melting range of EVA, in which the non-crosslinked crystalline phase fraction is already in the partly molten state. Double cantilever beam specimens were tested on an electrodynamic test machine at temperatures of 60, 70, 80, and 90°C and relative humidity (rh) levels of 2%, 30%, 50%, and 80%. The fractured surfaces were characterized by digital microscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and differential scanning calorimetry (DSC). The cyclic fatigue tests revealed a decay in delamination resistance at elevated temperature and humidity levels. At 70°C, the delamination resistance was low, regardless of the relative humidity. Most of the laminates failed by debonding. XPS analysis showed a reduction of the C=O and C–O content, along with an increase in Si–O content with increasing relative humidity. For laminates tested at 60 and 70°C, an EVA recrystallization peak was observed in DSC experiments. This peak was shifted to significantly higher temperatures at 80% rh. XPS and DSC indicated local hydrolysis within the porous fracture process zone ahead of the crack tip. Consequently, acetic acid formation led to a decrease in delamination resistance, resulting in lower fatigue threshold values. The investigations confirmed the significant impact of environmental conditions on the fatigue delamination resistance within glass/encapsulant laminates. Notably, acetic acid formation and a significant reduction in delamination properties were observed after around 100 h of environmental fatigue exposure.

Ultrathin solar cells are efficient and captivating devices with unique technological and scientific features in terms of minimal material consumption, fast fabrication processes, and good compatibility with semi-transparent applications. Such photovoltaic (PV) technologies can enable effective synergy between optical and electronic confinements with large tuning capabilities of all the optoelectronic characteristics. In this work, the implications of the optical design and the bandgap engineering in ultrathin hydrogenated amorphous Si/Ge multiple quantum well (MQW) solar cells featuring photonic nanocavity are analyzed based on experimental measurements and optoelectronic modelling. By changing the period thicknesses and the positions of QWs inside the deep-subwavelength nanophotonic resonator, the spatial and spectral distributions of the optical field and the local absorption are strongly affected. This leads to a modulation of the absorption resonance condition, the absorption edge and the resulting photocurrent outputs. Because of quantum confinement effect, the change of MQW configurations with different individual QW periods while keeping similar total thickness of about 20 nm alters both the bandgap energy and the band offset at the QW/barrier heterojunctions. This in turn controls the photovoltage as well as the carrier collection efficiency in solar cells. The highest open circuit voltage and fill factor values are achieved by employing MQW device configuration with 2.5 nm-thin QWs. A record efficiency above 5.5% is reached for such emerging ultrathin Si/Ge MQW solar cell technology using thinner QWs with sufficient number, because of the optimum trade-off between all the optoelectronic characteristic outputs. The presented design rules for opaque ultrathin solar cells with quantum-confined nanostructures integrated in a photonic nanocavity can be generalized for the engineering of relevant multifunctional semitransparent PV devices.

As PV manufacturing heads towards the multi-TW scale, it is required to carefully evaluate a wide range of concepts including not only efficiency and cost but also material consumption to ensure sustainable manufacturing of PV technologies. The rapid growth of PV could significantly increase the demand for several materials required in solar cells such as silver, aluminium, copper and even silicon, thereby causing dramatic price fluctuations. Furthermore, the PV manufacturing capacity would be at risk of being limited by the supply of some scarce metals, e.g. with current industrial implementations – screen printing (SP) metallization, the capacities of PERC and TOPCon could be capped at 377 GW and 227 GW with 20% of global silver supply available to the PV industry. In addition, PV systems have ~25–30 years lifespan to ensure low LCOE and emissions. Recycling alone will not provide an immediate solution to overcome the limitation of material consumption in the exponentially growing PV market. It is expected that the Ag usage needs to be reduced to no more than 5 mg/W or even 2 mg/W for all solar cell technologies to allow a multi-TW manufacturing scale without depleting the global silver supply. Therefore, further advancements in metallization technologies are critically and urgently required to significantly reduce the silver consumption of current screen-printed contacts in industrial silicon solar cells. This paper firstly presents a roadmap towards the 5 mg/W and 2 mg/W silver consumption targets with various metallization technologies and screen-printing designs. Subsequently, a hybrid plating on screen-printed metallization design was proposed to improve the performance and reduce the silver consumption of screen-printed contacts. The experimental results have demonstrated up to 1.08%_abs improvements in fill factor and 0.3%_abs gains in cell efficiency. In addition, up to 40%_rel reductions in finger silver consumption have been achieved without any sacrifices in the electrical conductivity of such hybrid screen-printed and plated fingers. This work proposes not only a roadmap but also a promising approach to significantly reduce the Ag demand and benefit sustainable production of industrial screen-printed silicon solar cells in the TW era.

In May 2022, the European Commission adopted a new European Union (EU) Solar Energy Strategy [1] aiming to ensure that solar energy achieves its full potential in helping to meet the European Green Deal's climate and energy targets. A goal of the strategy is to reach nearly 600 GW of installed solar photovoltaics (PV) capacity by 2030. While Europe is a pioneer in the definition of new policy requirements to ensure the circularity and sustainability of PV products, its manufacturing capabilities are limited. The EU mostly imports PV modules from China, which for the last decade has remained the global leader in PV manufacturing across the supply chain. This article aims to provide insight into the solar PV industry and the surrounding policy context, focusing on the manufacturing phase and its climate impact. It provides a comparative overview of the key players in the European and Chinese PV markets with an overview of the whole supply chain (i.e. production of polysilicon, cells, wafers and modules). Having in mind the net-zero commitments across the globe, and a central role of the solar PV in the energy transition, the demand for PV products is expected to grow exponentially in the next decades. With this in mind, the authors look into environmental impacts from the PV manufacturing. A simplified analysis concludes on the suitability of the PV manufacturing process today and indicates the opportunities for the net-zero transition in the future. While the focus is on the carbon impacts of the solar PV industry, the authors also identify other relevant aspects (such as circularity), laying the ground for a future research.

With the improvement of surface passivation, bulk recombination is becoming an indispensable and decisive factor to assess the theoretical limiting efficiency ($�{\eta }_{\lim }$) of crystalline silicon (c-Si) solar cells. In simultaneous consideration of surface and bulk recombination, a modified model of $�{\eta }_{\lim }$ evaluation is developed. Surface recombination is directly depicted with contact selectivity while bulk recombination is revised on the aspects of ideality factor and wafer thickness. The $�{\eta }_{\lim }$ of the double-side silicon heterojunction (SHJ) and double-side tunneling-oxide passivating contact (TOPCon) solar cells are numerically simulated using the new model as 28.99% and 29.19%, respectively. However, the $�{\eta }_{\lim }$ of single-side TOPCon solar cells, the more practicable scenario, is only 27.79%. Besides, the $�{\eta }_{\lim }$ of the double-side SHJ solar cells would exceed the double-side TOPCon solar cells if the recombination parameter of the non-contacted area is higher than 0.6 fA/cm², instead of perfect passivation. Our results are instructive in accurately assessing efficiency potential and accordingly optimizing design strategies of c-Si solar cells.