Comparison of Terminal and Implied Open-Circuit Voltage Measurements

Dumbrell, Robert; Juhl, Mattias K.; Trupke, Thorsten; Hameiri, Ziv

doi:10.1109/jphotov.2017.2729889

Cited by 16 publications

(8 citation statements)

References 19 publications

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“…However, this is not the case when the resistively isolated regions feature less overall recombination. In the presented example, Region 1 and Region 2 are resistively separated from the recombination under the busbars which then results in a slightly higher voltage and PL signal at V oc …”

Section: Applicationsmentioning

confidence: 98%

Outdoor photoluminescence imaging of solar panels by contactless switching: Technical considerations and applications

Bhoopathy

Kunz

Juhl

et al. 2019

Progress in Photovoltaics

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Monitoring the performance of solar modules in a photovoltaic system is critical in order to understand the health of the system. Existing methods for field inspection have limited capability of detecting various electronic defects that can, however, be identified with luminescence‐based methods. A contactless outdoor photoluminescence‐imaging based measurement method that uses the sun as the excitation source was presented in our earlier work. This paper extends our previous work and presents two unique applications to (a) identify and quantify local areas of high series resistance within the cells and (b) identify bypass diodes that have failed in open‐circuit. The paper also discusses specific technical considerations of this method. The main merit of this method is that it can be used when the module is under normal operation in the field, without requiring changing of the electrical wiring of the photovoltaic array.

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Section: Applicationsmentioning

confidence: 98%

Outdoor photoluminescence imaging of solar panels by contactless switching: Technical considerations and applications

Bhoopathy

Kunz

Juhl

et al. 2019

Progress in Photovoltaics

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“…This shadowing effect is reported to be of particular significance in front-junction solar cells. [34][35][36][37] In the rear-junction solar cells studied in this work the significance of this effect needs additional confirmation. Finally, part of the difference between iV OC and V OC can be explained by imperfect selective function of doped layerscarrier selectivity of the contacts [38][39][40] -especially in the highvoltage case of thinned wafers.…”

Section: Open-circuit Voltagementioning

confidence: 99%

“…The drop from iFF to pFF is smaller in the case of the reference wafer thickness and increases as the wafer thickness is reduced. Similar to V OC , this increased drop from iFF to pFF for thinner wafers could be as a result of increased effect of contact shadowing, [34][35][36] carrier selectivity of contacts, [38][39][40] and possibly defects caused during the metallization process. [42,43] The final FF values for all wafer thicknesses drop from the pFF due to the effect of series resistance.…”

Section: Fill Factormentioning

confidence: 99%

“…Even though certain degradation of carrier lifetime after screen printing cannot be excluded, we believe that the difference between iV OC and V OC is related to imperfect operation of carrier-selective contacts. Among several mechanisms reported in the literature as listed by Dumbrell et al, [34] the most relevant for SHJ solar cell technology is related to contact shadowing. [34][35][36] Light shadowing from the front contact leads to inhomogeneous generation of photocurrent, which results in internal currents from the open regions with high generation to the shadowed regions under metal contacts.…”

Section: Open-circuit Voltagementioning

confidence: 99%

“…Among several mechanisms reported in the literature as listed by Dumbrell et al, [34] the most relevant for SHJ solar cell technology is related to contact shadowing. [34][35][36] Light shadowing from the front contact leads to inhomogeneous generation of photocurrent, which results in internal currents from the open regions with high generation to the shadowed regions under metal contacts. The related voltage drop then is observed as the difference between iV OC and externally measured V OC .…”

Section: Open-circuit Voltagementioning

confidence: 99%

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How Thin Practical Silicon Heterojunction Solar Cells Could Be? Experimental Study under 1 Sun and under Indoor Illumination

et al. 2021

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The transition toward thinner microcrystalline silicon wafers for their potential performance gain has been of interest in recent years. Theoretical predictions have estimated a maximum efficiency for silicon wafers to be at about 100−110 μm thickness. The potential and losses in silicon heterojunction solar cells prepared on wafers with thickness in the range of 60−170 μm with focus on open‐circuit voltage (V OC) and fill factor (FF) are studied experimentally. The applicability of thinner wafers for low light and indoor applications using light emitting diode (LED) lighting is also studied. The implied V OC (iV OC) is observed to increase with a decrease in wafer thickness according to theoretical predictions with absolute values approaching the theoretical limit. Unlike the iV OC, the implied FF is observed to decrease with wafer thickness reduction opposite to the theoretical predictions which are related to the effect of surface recombination. A combination of gains and losses results in a broad range of high efficiency under 1 sun for wafer thicknesses ranging from 75 to 170 μm with maximum of 22.3% obtained at 75 μm. As for indoor performance, thinner wafers show slightly better efficiency at lower light intensity under sun and LED illumination, promising improved performance for even thinner devices.

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Implied Open‐circuit Voltage Imaging via a Single Bandpass Filter Method—Its First Application in Perovskite Solar Cells

Soufiani

Lee‐Chin

Faßl

et al. 2022

Adv Funct Materials

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A novel, camera-based method for direct implied open-circuit voltage (iV OC ) imaging via the use of a single bandpass filter (s-BPF) is developed for largearea photovoltaic solar cells and precursors. The photoluminescence (PL) emission is imaged using a narrow BPF with centre energy inside the highenergy tail of the PL emission, utilising the close-to-unity and nearly constant absorptivity of typical photovoltaic devices in this energy range. As a result, the exact value of the sample's absorptivity within the BPF transmission band is not required. The use of an s-BPF enables a fully contactless approach to calibrate the absolute PL photon flux for spectrally integrated detectors, including cameras. The method eliminates the need for knowledge of the imaging system spectral response. Through an appropriate choice of the BPF centre energy, a range of absorber compositions or a single absorber with different surface morphologies, such as planar and textured, can be imaged, all without the need for additional detection optics. The feasibility of this s-BPF method is first validated. The relative error in iV OC is determined to be ≤1.5%. The method is then demonstrated on device stacks with two different perovskite compositions commonly used in single-junction and monolithic tandem solar cells.

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Comparison of Terminal and Implied Open-Circuit Voltage Measurements

Cited by 16 publications

References 19 publications

Outdoor photoluminescence imaging of solar panels by contactless switching: Technical considerations and applications

Outdoor photoluminescence imaging of solar panels by contactless switching: Technical considerations and applications

How Thin Practical Silicon Heterojunction Solar Cells Could Be? Experimental Study under 1 Sun and under Indoor Illumination

Implied Open‐circuit Voltage Imaging via a Single Bandpass Filter Method—Its First Application in Perovskite Solar Cells

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