Progress in Photovoltaics最新文献

Previous studies have shown that soiling losses on photovoltaic (PV) modules can lead to reduced power output of up to 80% in PV systems. Therefore, accurate determination of soiling loss plays a crucial role in predicting PV output and ensuring optimized cleaning schedules. The study focused on measuring soiling loss at a 1.1 MW outdoor testing facility in Louisiana, United States, using a DustIQ device, a commercially available soiling sensor. The maximum soiling loss recorded for DustIQ Sensor 1 was 7.5% on August 27, 2023, during the dry season. The measured data was fitted using the well-established Kimber and HSU models (based on PM_2.5 and PM₁₀) by optimizing the least squares error, resulting in observed mean absolute percentage error (MAPE) of approximately 0.82% and 0.78%, respectively. One feature of these models is that it is assumed that the solar panels will be completely cleaned after a rain event that reaches a set threshold limit. However, in-field testing at the site shows that assumption to be flawed, because the soiling ratio did not return to 1 or 100% even after significant rainfall events. To address this, improved versions of the Kimber and HSU models were developed to more accurately represent the recovery of the soiling ratio after rainfall events. The results demonstrated significant improvements, with the modified Kimber models achieving reductions in root mean squared error (RMSE) of 23%, 13%, and 1% compared to the optimized Kimber model, while the modified HSU model exhibited a 12% reduction in RMSE over the optimized HSU model. The overall MAPE was less than 1% for all models.

Among reliability studies on perovskite photovoltaics (PV) cells and modules, partial shading degradation is a crucial and under-investigated topic. In the present work, we use a combination of mapping electroluminescence (EL), photoluminescence (PL), and illuminated lock-in thermography (ILIT) to gain insight into the reverse bias degradation mechanisms induced by partial shading on a monolithically interconnected module. Spatial inhomogeneities across the cell length are shown to play an important role in the degradation. A perovskite module was subjected to partial shading, causing, in the lower region of the shaded cells, a PL signal intensity increase and EL decrease. We suggest the formation of a barrier at one of the perovskite/transport layer interfaces, preventing both carrier extraction in PL and carrier injection in EL. A simple model for the current flow in the presence of the barrier can satisfactorily explain the EL, PL, and ILIT behavior and point to some possible propagation mechanisms. In summary, we show that studying partial shading degradation at module level draws a more complex and realistic picture of the interplay between material and electrical parameters than cell-level studies. We also demonstrate that luminescent and thermal imaging techniques can be combined to draw meaningful conclusions on the degradation mechanisms, their formation, and propagation.

Encapsulation is a critical topic to ensure the successful implementation of perovskite photovoltaics. Recently, vacuum lamination has been shown as a promising approach that combines compatibility with current industrial processes in conventional photovoltaic (PV) manufacturing and suitability to achieve good results with perovskites. Here, we explore some of the attractive encapsulation materials in terms of their ability to prevent moisture ingress, withstand elevated temperatures, and have suitable mechanical properties to avoid thermomechanical issues. We utilized the previously suggested concept of the “perovskite test,” an optical test with simple sample fabrication, for evaluating encapsulation quality and validated the findings with the full solar cell stack. Unsurprisingly, encapsulants without an edge sealant showed insufficient protection from moisture. Ionomer in combination with butyl edge seal showed the best barrier properties; however, this stack led to rapid delamination of the cell layers in thermal cycling tests. Configuration with only edge sealant does not have such an issue in principle (no mechanical stress applied), but an absence of the polymer in the stack is unfavorable in terms of optical design and sometimes showed perovskite degradation that we assign to trapped moisture in the butyl itself. Polyolefin with butyl edge sealant is not free of degradation but showed the most promising compromise by passing the damp heat test and showing fewer issues in the thermal cycling experiments. In general, our material study and optimization presented in this manuscript show that a holistic approach is needed when choosing an optimal encapsulation scheme for perovskite devices.

For high-efficiency solar cells, such as Si-III-V tandem solar cells, implementing narrow contact fingers is essential for achieving optimal conversion efficiencies. By achieving narrower contact fingers without compromising electrical performance, more sunlight reaches the active areas of the cell, thus reducing front-side shading and enhancing overall energy conversion efficiency. In this work, we demonstrate a proof of principle for a novel low-temperature metallization process using glass stencils to print ultra-fine line contacts. The narrowest contacts achieved have a width of $�w_f$ = 8.4 ± 1.3 with an aspect ratio of $�{\mathrm{AR}}_{\mathrm{opt}}$ = 0.19 ± 0.05. Through optimization described in this work, contact fingers with $�w_f$ = 9.7 ± 0.6 μm and a substantially greater aspect ratio of $�{\mathrm{AR}}_{\mathrm{opt}}$ = 0.45 ± 0.1 could be achieved. To realize these ultra-fine line fingers, glass stencils with tailored aperture channels were realized using a two-step laser induced deep etching (LIDE) process that enables complex three-dimensional aperture channel geometries.

This study investigates mismatch losses in PV modules, analyzing the impact of operational conditions and degradation mechanisms on power generation across different module designs: full-cell, half-cell, string-shingled, and matrix-shingled. A bottom-up multi-physics model assesses inhomogeneities like partial shading, temperature inhomogeneity, soiling, encapsulation aging, and bypass diode failure. Module design related analysis reveals that parallel connections within modules minimize current mismatch losses, enhancing power under partial shading. Furthermore, modules exhibit a temperature profile with maximum temperatures at the center and minimum at the corners, impacting power differently based on the module's internal geometry, cell size, and electrical layout. Degradation analysis reveals significant power reduction due to soiling width and orientation, with encapsulation aging causing a 2% power loss after 3000 h. Findings indicate that partial shading and bypass diode failure can reduce full-cell module power to zero under vertical shading; half-cell and shingled modules retain varying power under horizontal and diagonal shading. Matrix-shingled modules perform best under partial shading due to additional lateral current paths. Yield analysis shows a 1.7-kWh annual yield increase for the matrix-shingled module, attributed to changes in cell-specific irradiance and temperature from its unique design, compared to a 0.5-kWh increase for the full-cell module. It was observed that shingled modules have a 1.6% higher specific yield under accumulating soiling along the long edge, which drops to 0.4% when considering module cleaning. For soiling along the short edge, results show that full-cell modules exhibit the highest specific yield. Furthermore, findings indicate that portrait mounting reduces annual yield by about 5% for shingled modules, compared to 3% for full-cell and half-cell modules, with landscape mounting having a lower negative impact on yield. Overall, this research identifies the strengths and weaknesses of various PV module designs under different degradation and inhomogeneity scenarios, advancing the development of more efficient modules and enhancing accurate energy yield predictions, thus significantly contributing to the sustainability of solar energy.

Lightweight photovoltaic applications are essential for diversifying the solar energy supply. This opens up vast new scenarios for solar modules and significantly boosts the capacity of renewable energy. To ensure high efficiency and stability of the solar modules, several challenges need to be overcome. Degradation due to elevated temperature and/or humidity is a critical concern for silicon heterojunction (SHJ) solar modules. Here, we investigated the stability and degradation mechanism of encapsulated cells with lightweight configurations where the cells are based on three different types of transparent-conductive oxide (TCO): indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), and a combination of ITO/AZO/ITO under humid and thermal environmental conditions. A damp heat (DH) test at a temperature of 85°C and relative humidity (RH) of 85% was performed on lightweight modules for 1000 h. Our results show that AZO is the most susceptible to DH degradation. The AZO film was damaged by the combined effects of moisture ingress and delamination of the interconnection foil, resulting in a decrease in the conductivity of the AZO film, leading to a dramatic increase in R_s and a decrease in FF of the modules. Consequently, moisture has a greater chance of percolating through the damaged AZO layer into the a-Si:H passivation layer, causing passivation degradation, which leads to an increase in recombination, resulting in a decrease in V_oc of the modules. In particular, after capping the AZO film with an ITO film, the efficiency loss of the ITO/AZO/ITO module was significantly reduced. This suggests that the ITO film could be a promising protective capping layer for the AZO-based solar cells.

Both metallization material consumption and module recycling are growing concerns in photovoltaic (PV) sector. In order to overcome these challenges, we present a module designed to facilitate recycling with no dispersive material consumption in interconnection while maintaining high module performances. Our approach aims to overcome these limitations by integrating a liquid optical coupling layer and carefully optimized front cover. This new glass-glass module architecture comprises six elements. First, a solid polymer layer is melt on the intern side of the glass plates in which are embedded the connectors blocks their movements. Second, a transparent liquid layer around the cells maintains an optical index progression all along the light path to the cell surface as well as it separates the polymer layer from sticking to the cell surface. Finally, an edge sealant is melt on the periphery of glass plates to form a mechanical contact between connectors and metallization, and to seal the liquid layer. Optical simulations have been performed to ensure the optical relevance of this structure. A simple thermal model has also been developed to verify the thermal heat dissipation potential of this architecture. Last but not least, proof of concept modules have been fabricated and submitted to accelerated aging tests.