Three Bypass Diodes Architecture at the Limit

Witteck, Robert; Siebert, Michael; Blankemeyer, Susanne; Schulte‐Huxel, Henning; Köntges, Marc

doi:10.1109/jphotov.2020.3021348

Cited by 20 publications

(6 citation statements)

References 37 publications

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“…The most important mechanism for junction breakdown in monocrystalline silicon solar cells is avalanche breakdown [16,17]. This breakdown occurs at reverse bias voltages below À20V for PERC cells, the most common type of mass-produced solar cell [10]. Junction breakdown occurs at the weakest point in the cell area.…”

Section: Hot-spot Phenomenamentioning

confidence: 99%

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The effect of partial shading on the reliability of photovoltaic modules in the built-environment

Özkalay,

Valoti,

Caccivio

et al. 2024

EPJ Photovolt.

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Residential photovoltaic systems often experience partial shading from chimneys, trees or other structures, which can induce hot-spots in the modules. If the temperature and frequency of these hot-spots are high, the module's reliability and safety may be at risk. IEC 61215-2:2021 hot-spot endurance test is utilized to evaluate the materials' ability to withstand partial shading. Since modules in residential systems can be subjected to higher temperatures than those in the open field, IEC TS 63126:2020 recommends adjusting the module temperature for the hot-spot endurance test according to the module's operating temperature. This study tested the hot-spot endurance of PERC, IBC and HJT modules under standard (55 °C) and more severe (75 °C, Level 2 condition in IEC TS 63126:2020) test conditions, as well as outdoor accelerated-ageing tests were performed with shadow masks. The results demonstrated that irrespective of environmental conditions, hot-spots can form at lower temperatures, with more shading-tolerant cells (i.e., cells with lower breakdown voltage) or with shorter strings. We also show that it is possible to shorten the effort- and time-consuming hot-spot endurance test described in the standard and obtain similar results. In addition, the hot-spot endurance test for residential PV systems was evaluated in terms of module temperatures and duration. In this respect, we propose to increase the testing temperatures of the hot-spot endurance testing for modules operating at high temperatures in IEC TS 63126:2020.

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Section: Hot-spot Phenomenamentioning

confidence: 99%

“…In contrast, the International Energy Agency (IEA) states that the hot-spot can be caused by (i) reverse bias and junction breakdown of a solar cell, (ii) damaged cell, or (iii) damaged metallisation [9]. The reason why the term "hotspot" is defined differently is explained in [10].…”

Section: Introductionmentioning

confidence: 99%

The effect of partial shading on the reliability of photovoltaic modules in the built-environment

Özkalay,

Valoti,

Caccivio

et al. 2024

EPJ Photovolt.

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“…The primary protection approach utilized recently against reverse bias situations is a passive bypass Schottky diode that is arranged in parallel with a string of cells [ 31 , 32 , 33 ]. Additionally, the latest investigations emphasize alleviating the influence of localized overheating or hot spots and improving the module reliability by adapting the bypass (protection) circuit [ 34 , 35 , 36 , 37 , 38 , 39 ]. However, the protection circuits or the bypass Schottky diodes can result in consuming more power and complicating the design, as well as raising the module costs.…”

Section: Introductionmentioning

confidence: 99%

Design and Optimization of a Self-Protected Thin Film c-Si Solar Cell against Reverse Bias

et al. 2023

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Current mismatch due to solar cell failure or partial shading of solar panels may cause a reverse biasing of solar cells inside a photovoltaic (PV) module. The reverse-biased cells consume power instead of generating it, resulting in hot spots. To protect the solar cell against the reverse current, we introduce a novel design of a self-protected thin-film crystalline silicon (c-Si) solar cell using TCAD simulation. The proposed device achieves two distinct functions where it acts as a regular solar cell at forward bias while it performs as a backward diode upon reverse biasing. The ON-state voltage (VON) of the backward equivalent diode is found to be 0.062 V, which is lower than the value for the Schottky diode usually used as a protective element in a string of solar cells. Furthermore, enhancement techniques to improve the electrical and optical characteristics of the self-protected device are investigated. The proposed solar cell is enhanced by optimizing different design parameters, such as the doping concentration and the layers’ thicknesses. The enhanced cell structure shows an improvement in the short-circuit current density (JSC) and the open-circuit voltage (VOC), and thus an increased power conversion efficiency (PCE) while the VON is increased due to an increase of the JSC. Moreover, the simulation results depict that, by the introduction of an antireflection coating (ARC) layer, the external quantum efficiency (EQE) is enhanced and the PCE is boosted to 22.43%. Although the inclusion of ARC results in increasing VON, it is still lower than the value of VON for the Schottky diode encountered in current protection technology.

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“…For a PV array, edge soiling causes inhomogeneous solar irradiance, leading to an electrical mismatch between the components, and aggravating the power output [13][14][15]. Bypass diodes have been introduced to mitigate the current mismatch between series [16]. However, they also bring multiple electrical power output peaks in the power characteristic curves.…”

Section: Introductionmentioning

confidence: 99%

Comparative Analysis of Edge Soiling Resilience: Full-Cell vs. Half-Cell Photovoltaic Modules in Different Mounting Orientations

Zhou,

Yu,

Yuetikuer

et al. 2023

Journal of Engineering

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The performance of distributed PV systems is often hindered by edge soiling, mainly due to the challenges associated with centralized cleaning. In recent years, half-cell modules have gained popularity over conventional full-cell modules due to their potential for improved performance. However, limited research has been conducted to compare the effects of edge soiling on full-cell and half-cell modules, particularly in various mounting orientations. Furthermore, there is a scarcity of methods that integrate simulation and experimentation to analyze the characteristics of shaded PV modules. This study aims to optimize module selection and mounting orientation to mitigate the impact of edge soiling. Simulated models and experimental setups were developed for both full-cell and half-cell modules in both landscape and portrait orientations. The results reveal that the degree of shading correlates with the ratio of shaded substrings within a module. In addition, module performance can be significantly enhanced by altering the mounting orientation. Specifically, the findings demonstrate that half-cell modules outperform full-cell modules when mounted in the portrait orientation. However, in the landscape orientation, the advantage of half-cell modules diminishes. Remarkably, the choice of mounting orientation is found to be contingent on the severity of edge soiling for half-cell modules. This work significantly contributes to the understanding of shading effects in PV systems and offers practical guidance for optimizing distributed PV systems against edge soiling.

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Three Bypass Diodes Architecture at the Limit

Cited by 20 publications

References 37 publications

The effect of partial shading on the reliability of photovoltaic modules in the built-environment

The effect of partial shading on the reliability of photovoltaic modules in the built-environment

Design and Optimization of a Self-Protected Thin Film c-Si Solar Cell against Reverse Bias

Comparative Analysis of Edge Soiling Resilience: Full-Cell vs. Half-Cell Photovoltaic Modules in Different Mounting Orientations

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