Compressive light beam induced current sensing for fast defect detection in photovoltaic cells

Lei, Qunfang; Xie, Kai; Xi, Ruoyao; Liu, Yan

doi:10.1016/j.solener.2017.04.059

Cited by 10 publications

(4 citation statements)

References 21 publications

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“…The use of a liquid crystal display (LCD) screen used as a light source and pattern generator for CS current mapping of solar cells has been presented. [21] CS has a different response to measurement noise from raster scanning and different dynamic range requirements, with such potential advantages already having been identified. [22] Although there is clear progress toward faster current mapping and more simplistic layouts through the use of DMDs and CS, there are still several issues to be resolved.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Toward Megapixel Resolution Compressed Sensing Current Mapping of Photovoltaic Devices Using Digital Light Processing

2021

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Photocurrent response mapping is a powerful imaging technique for assessing defects and losses in photovoltaic devices. However, it has not enjoyed widespread application because high‐resolution measurements of large samples can last several hours, while weak signals from micrometer‐sized laser spots require lock‐in amplification. An alternative approach presented recently is the use of digital micromirror devices combined with compressed sensing theory. There are significant benefits when using such methods, such as signal amplification, undersampling options, and simplified measurement systems. Nevertheless, high computational requirements have limited the experimental application of this method to low‐resolution outputs. Herein, the mathematical background and the experimental approach toward megapixel resolution, ultrafast compressed sensing current mapping are presented, overcoming previous computational and experimental barriers. A high‐power digital light processing projection system is developed for the experimental application. Solutions to computational issues, sampling optimization, and measurement strategies are presented and the flexibility of the system regarding the sizes of photovoltaic devices that can be measured is demonstrated.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Toward Megapixel Resolution Compressed Sensing Current Mapping of Photovoltaic Devices Using Digital Light Processing

2021

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“…In this work, a high speed, high resolution linearity measurement method for PV devices and photodiodes based on a digital light processing (DLP) projection system is presented. DLP projection systems have already been demostrated for PV cell spatial characterisation [16][17][18] and PV module testing [19,20]. The proposed method uses a digital micromirror device (DMD) [21], integrated in a custom projection system to apply high resolution mechanical shading for linearity measurements.…”

Section: Introductionmentioning

confidence: 99%

High-resolution linearity measurements of photovoltaic devices using digital light processing projection

Koutsourakis

Eales

Ingo

et al. 2021

Meas. Sci. Technol.

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Although photovoltaic (PV) devices are rated at standard testing conditions (STCs), these STCs are rarely met, either outdoors, or when PV devices are used for indoor applications. Thus, it is beneficial to fully characterise the linearity of PV devices with respect to irradiance. Moreover, high accuracy linearity measurements are essential for reference cells (RCs), as they ensure the precision of the measured irradiance. This work presents a new technique for linearity measurements of PV devices based on digital light processing (DLP). The proposed system uses a digital micromirror device coupled with projection optics and a high-power LED array. By creating a series of patterns projected on the device under test with a specific number of bright and dark pixels, linearity measurements can be implemented through a spatial dithering process. Since the dithering process is mechanical, it is expected that any spectral variability effects for the different dithering levels or electrical non-linearities of the light source are avoided. The developed system can provide thousands of measurement points on the linearity curve of a device in seconds, which is impossible with any other currently established methods. Measurements of RCs with known linearity curves are acquired and are validated by conventional methods. Results demonstrate that the DLP method provides equal measurement accuracy compared to conventional systems, but at significantly higher resolution (points on the linearity curve) and order of magnitude higher measurement speed.

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“…Using a DMD to apply compressed sensing (CS) current mapping of PV devices has been demonstrated in recent work [22,23,24]. CS current mapping has also been demonstrated by utilising an LCD (liquid crystal display) monitor to project the necessary patterns for compressive sampling [25]. The CS current mapping method is based on the CS sampling theory [26,27].…”

Section: Introductionmentioning

confidence: 99%

Signal Amplification Gains of Compressive Sampling for Photocurrent Response Mapping of Optoelectronic Devices

Koutsourakis

Blakesley

Castro

2019

Sensors

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Spatial characterisation methods for photodetectors and other optoelectronic devices are necessary for determining local performance, as well as detecting local defects and the non-uniformities of devices. Light beam induced current measurements provide local performance information about devices at their actual operating conditions. Compressed sensing current mapping offers additional specific advantages, such as high speed without the use of complicated experimental layouts or lock-in amplifiers. In this work, the signal amplification advantages of compressed sensing current mapping are presented. It is demonstrated that the sparsity of the patterns used for compressive sampling can be controlled to achieve significant signal amplification of at least two orders of magnitude, while maintaining or increasing the accuracy of measurements. Accurate measurements can be acquired even when a point-by-point scan yields high noise levels, which distort the accuracy of measurements. Pixel-by-pixel comparisons of photocurrent maps are realised using different sensing matrices and reconstruction algorithms for different samples. The results additionally demonstrate that such an optical system would be ideal for investigating compressed sensing procedures for other optical measurement applications, where experimental noise is included.

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Compressive light beam induced current sensing for fast defect detection in photovoltaic cells

Cited by 10 publications

References 21 publications

Toward Megapixel Resolution Compressed Sensing Current Mapping of Photovoltaic Devices Using Digital Light Processing

Toward Megapixel Resolution Compressed Sensing Current Mapping of Photovoltaic Devices Using Digital Light Processing

High-resolution linearity measurements of photovoltaic devices using digital light processing projection

Signal Amplification Gains of Compressive Sampling for Photocurrent Response Mapping of Optoelectronic Devices

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