In the photovoltaic industry, there are three critical parameters such as module power, cost and reliability. For increasing module power, half-cutting technology on the cell is one of the ...technologies because this can reduce the heating power by reducing the current. Therefore, laser scribing and mechanical cleaving (LSMC) technology have been implemented. As a result, the power of the module did not show any loss during standard test conditions when electrical luminescence and powers were monitored for the laser dicing process. However, in field conditions, the cut side of the cells with the laser process can cause cell breakage by wind or snow if the side has cracks. And then these crack cells can finally cause module power loss. Therefore, in this study, the laser process quality of the cell has been investigated by microscope image and scanning electron microscopy with laser process parameters such as laser power, frequency, and pulse width. In addition, cell strength was also checked by the four points of bending force to find the optimized laser process condition. The module power loss was analyzed with a static mechanical load test (MLT), which can represent snow or wind effect in the field. Our analyses show a strong correlation between crack width by laser, cell bending force, and module power loss. This correlation can explain the module power loss estimation, which can affect the reliability in the field without making module-level tests for the first time. In addition, the encapsulant thickness combination test and the mid-rail effect were also presented to reduce the power loss. As a result, the module power loss reached -1.34%. Finally, this study can contribute to the better reliability of the big wafer size products with LSMC technology.
Perovskite solar cells have great potential for high efficiency generation but are subject to the impact of external environmental conditions such as humidity, UV and sun light, temperature, and ...electric fields. The long-term stability of perovskite solar cells is an important issue for their commercialization. Various studies on the stability of perovskite solar cells are currently being performed; however, the stability related to electric fields is rarely discussed. Here the electrical stability of perovskite solar cells is studied. Ion migration is confirmed using the temperature-dependent dark current decay. Changes in the power conversion efficiency according to the amount of the external bias are measured in the dark, and a significant drop is observed only at an applied voltage greater than 0.8 V. We demonstrate that perovskite solar cells are stable under an electric field up to the operating voltage.
Abstract
In this study, we employ a combination of various
in-situ
surface analysis techniques to investigate the thermally induced degradation processes in MAPbI
3
perovskite solar cells (PeSCs) as ...a function of temperature under air-free conditions (no moisture and oxygen). Through a comprehensive approach that combines
in-situ
grazing-incidence wide-angle X-ray diffraction (GIWAXD) and high-resolution X-ray photoelectron spectroscopy (HR-XPS) measurements, we confirm that the surface structure of MAPbI
3
perovskite film changes to an intermediate phase and decomposes to CH
3
I, NH
3
, and PbI
2
after both a short (20 min) exposure to heat stress at 100 °C and a long exposure (>1 hour) at 80 °C. Moreover, we observe clearly the changes in the orientation of CH
3
NH
3
+
organic cations with respect to the substrate in the intermediate phase, which might be linked directly to the thermal degradation processes in MAPbI
3
perovskites. These results provide important progress towards improved understanding of the thermal degradation mechanisms in perovskite materials and will facilitate improvements in the design and fabrication of perovskite solar cells with better thermal stability.
Although the power conversion efficiency of perovskite solar cells has increased from 3.81% to 22.1% in just 7 years, they still suffer from stability issues, as they degrade upon exposure to ...moisture, UV light, heat, and bias voltage. We herein examined the degradation of perovskite solar cells in the presence of UV light alone. The cells were exposed to 365 nm UV light for over 1,000 h under inert gas at <0.5 ppm humidity without encapsulation. 1-sun illumination after UV degradation resulted in recovery of the fill factor and power conversion efficiency. Furthermore, during exposure to consecutive UV light, the diminished short circuit current density (J
) and EQE continuously restored. 1-sun light soaking induced recovery is considered to be caused by resolving of stacked charges and defect state neutralization. The J
and EQE bounce-back phenomenon is attributed to the beneficial effects of PbI
which is generated by the decomposition of perovskite material.
Abstract
Organic-inorganic hybrid perovskite solar cells (PSCs) have been extensively studied because of their outstanding performance: a power conversion efficiency exceeding 22% has been achieved. ...The most commonly used PSCs consist of CH
3
NH
3
PbI
3
(MAPbI
3
) with a hole-selective contact, such as 2,2′,7,7′-tetrakis(
N
,
N
-di-
p
-methoxyphenylamine)-9,9-spiro-bifluorene (spiro-OMeTAD), for collecting holes. From the perspective of long-term operation of solar cells, the cell performance and constituent layers (MAPbI
3
, spiro-OMeTAD, etc.) may be influenced by external conditions like temperature, light, etc. Herein, we report the effects of temperature on spiro-OMeTAD and the interface between MAPbI
3
and spiro-OMeTAD in a solar cell. It was confirmed that, at high temperatures (85 °C), I
−
and CH
3
NH
3
+
(MA
+
) diffused into the spiro-OMeTAD layer in the form of CH
3
NH
3
I (MAI). The diffused I
−
ions prevented oxidation of spiro-OMeTAD, thereby degrading the electrical properties of spiro-OMeTAD. Since ion diffusion can occur during outdoor operation, the structural design of PSCs must be considered to achieve long-term stability.
In the photovoltaics (PV) industry, bifacial modules have already captured approximately 30% of the market share in 2022. This is attributed to their ability to yield higher energy output and lower ...the levelized cost of electricity (LCOE) compared to monofacial modules due to increased absorption from the rear side. The extent of rear-side absorption is dependent on bifaciality, which is the ratio of rear-side module power to front side module power. Therefore, a higher bifaciality can lead to increased module power in the field, resulting in higher energy yields. This study investigates the current mismatch effect on bifacial modules, specifically addressing cell mixing in mass production. Through test samples, it was determined that this effect is more critical in bifacial modules compared to monofacial modules. This research aims to contribute to the PV industry by providing methods to mitigate current mismatch and improve bifaciality of passivated emitter and rear contact (PERC) cells, especially for large wafer sizes such as M10 (182 × 182 mm
2
) or M12 (210 × 210 mm
2
) products in the future. The research result of this paper can enhance energy yields and reduce LCOE.
In the photovoltaic (PV) industry, module manufacturers have begun to install bifacial cells into monofacial modules because of their lower production costs relative to monofacial cells. This is ...linked mainly to a 65.3% reduction in rear aluminum paste consumption and the corresponding 0.5 cent/wafer cost reduction for M4 (161.7 × 161.7 mm2) size wafers. Therefore, this study compared the performance of monofacial PV modules with the monofacial cells as a reference group and bifacial cells as the test group to determine the cost reduction potential of the latter in terms of energy yield. Fifteen modules of each type were installed in a solar carport system on the Korean Peninsula and recorded irradiance and ambient and module temperature for one year. Throughout the year, irradiance and energy yield exhibited a strong linear correlation. The total annual energy yields of the monofacial and bifacial cells were 1,093.1 and 1,098.9 kWh/kWp, respectively. The energy yield of the bifacial module was 5.8 kWh/kWp (0.53%) higher than that of the monofacial module. Thus, monofacial modules with bifacial cells may be used in the PV industry to reduce cell production costs and levelized cost of electricity while enhancing energy yields and overall product performance in carport systems on the Korean Peninsula during all four seasons.
This study analyzes the field performance of various solar cell designs. Most research and development efforts concerning solar cells aim to increase their efficiency or power under standard test ...conditions (STC). However, conducting an actual field performance analysis is crucial because of the various ambient conditions present in the field, including temperature, irradiance, PV system installation, and albedo. These conditions can result in different performance results compared to STC. This study compares and analyzes case studies to assess field performance. One particular case study compares the field performance of monofacial modules with a monofacial passivated emitter and rear cell (PERC) and bifacial PERC at a carport system in the ambient conditions of the Korean Peninsula during summer and winter. The module material properties (white EVA and white backsheet) can impact module performance owing to the transmittance spectra at longer wavelengths. Certain transmittance values also contribute to the bifaciality number. Although the monofacial cell demonstrates better STC results, the field performance of the bifacial cell is superior in terms of energy yield and cost-effectiveness. Therefore, this study highlights the importance of considering the field performance (energy yield), in addition to STC, when designing solar cells and modules.
•Bifacial cells enhance seasonal energy yield.•STC data may not predict field performance accurately.•Bifacial cells reduce aluminum paste consumption and costs.•Findings can potentially contribute to lowering LCOE in PV industry.
Shunt defects are often detected in solar panels intended for photovoltaic applications. However, existing nondestructive detection technologies have certain inherent drawbacks depending on the ...application scenario. In this context, this paper reports a comprehensive empirical investigation into lock-in thermography (LIT) and its applicability to diagnosing shunt defects in copper indium gallium selenide (CIGS) solar modules. LIT was compared with biased thermography, and its distinctive attributes were elucidated. The comparison results demonstrate the superior capabilities of LIT at enhancing the signal-to-noise ratio, improving the visibility, resolution, and quantification of defects, and highlighting the usefulness of LIT for advanced defect analysis. We explored scenarios in which biased thermography could be appropriate despite its inherent limitations and identified conditions under which it might be preferred. The complex thermal behavior of different types of defects under various voltage conditions was analyzed, contributing to a more nuanced understanding of their behavior. Thus, integrating experimental results and theoretical understanding, we provide valuable insights and scientific guidelines for photovoltaic research. Our findings could help enhance the efficiency of defect detection in CIGS modules, highlighting the critical role of optimized thermographic techniques in developing photovoltaic technologies.
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