https://uvadoc.uva.es/handle/10324/1244 Dpto. Física de la Materia Condensada, Cristalografía y Mineralogía - Comunicaciones a congresos, conferencias, etc. Wed, 08 Apr 2026 16:52:56 GMT 2026-04-08T16:52:56Z https://uvadoc.uva.es/handle/10324/83965 This work presents a novel database architecture designed to support laboratory-based experimentation with photovoltaic (PV) cells and modules using different kinds of measurements, such as Electroluminescence (EL) Images or Current-Voltage (I-V) curves. The database is implemented in MySQL following established design principles. A web-based application is presented for efficient data insertion and retrieval. The initial population includes over 800 EL images and I–V curves of PV cells, and more than 1100 records of PV modules from diverse installations. This database provides a foundational tool for advancing automated diagnostics, performance analysis, and the integration of Artificial Intelligence in PV research environments. Future work will focus on enhancing the system’s scalability, interoperability, and support for real-time data ingestion and user management. Thu, 01 Jan 2026 00:00:00 GMT https://uvadoc.uva.es/handle/10324/83965 2026-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/81868 Daylight electroluminescence (dEL) inspection using InGaAs cameras has proven to be a powerful technique for assessing the condition of photovoltaic (PV) modules in the field. Recent advancements have shown it suitable for quality control and evaluation tasks in large-scale solar installations. The quality of dEL images is crucial for accurately identifying potential defects. Therefore, it is important to determine which camera optical stack yields stronger signals in dEL imaging. Camera optical stacks typically include specialized short-wave infrared (SWIR) lenses and bandpass filters to reduce background sunlight. To further limit the light intensity reaching the sensor and prevent saturation, options include adjusting the lens iris, using neutral density (ND) filters, or reducing exposure time. The choice among these depends on system constraints. Even though reducing exposure time is the easiest way to accomplish no saturation, high exposure time reduces noise, so ND filters and the iris are interesting options independent of the camera’s internal controller. This study compares the light intensity reduction methods between ND filters and iris providing higher EL and dEL image quality using signal-to-noise ratio (SNR) as metric. Two SNR metrics (SNRkari and SNR(25)) are used to evaluate the configurations. We compare two setups: one using a C-RED 3 InGaAs camera with a SWIR lens (F-stop range 1.4–16) and a bandpass filter, and another using the same camera and lens fixed at Fstop 1.4 (fully open) combined with ND filters of varying transmittance (0.73 to 0.02). Indoor EL data is used to characterize light attenuation for each configuration. Subsequently, dEL images are captured under 600-800 W/m² irradiance for both setups. The results show that using the iris to reduce light intensity yields higher image quality. This is attributed to the increased depth of field resulting from a smaller optical aperture, which enhances the focus range and sharpness of the captured images. In conclusion, the study demonstrates that using a lens with an adjustable iris is more effective for dEL imaging with InGaAs cameras. This finding is valuable for optimizing optical setups to achieve high-SNR images in PV module inspections. Wed, 01 Jan 2025 00:00:00 GMT https://uvadoc.uva.es/handle/10324/81868 2025-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/81867 Daylight Electroluminescence and Photoluminescence techniques (dEL/dPL) have rapidly advanced in recent years and are now well-established tools for the characterization of photovoltaic (PV) Si solar modules in the field. Performing dEL/dPL requires cameras capable of working in the near IR region of the light spectrum (such as InGaAs cameras) and sophisticated filtering procedures to distinguish the weak luminescence emission coming from the PV module from the more intense ambient light. Effective filtering of the weak luminescence requires specific acquisition schemes, both synchronous and asynchronous methods can be used for this purpose. Asynchronous schemes are more convenient, but they usually rely in expensive programmable power sources that produce high quality square or sinusoidal waveforms for the controlled current injection into the PV modules. When paired with fast InGaAs cameras (600 fps), dEL images can be obtained using very short (sub-second) acquisition times. However, the requirement for these programmable power sources may be a significant barrier to rapid in-field deployment of the technique. In this work we show the results of using asynchronous daylight luminescence inspections obtained without programmable power sources, using external control to modulate a DC signal from any power source, including the neighbor panels, or even without the use of a power source but using the Sun as the light source, in the dPL case. We specifically study the shape of the generated current and voltage signals, comparing the external control case with the case of using a programable power source. We also study the impact of varying the modulation frequency and camera speed on image quality and how these acquisition parameters influence performance. This approach broadens the applicability of the dEL technique, enabling effective filtering and identification of panel defects under self-powered or sunlight-driven conditions. Wed, 01 Jan 2025 00:00:00 GMT https://uvadoc.uva.es/handle/10324/81867 2025-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/75338 Silicon nanowires (NWs) with axial homojunctions have exhibited superior forward current density compared to traditional bulk silicon p-n junctions, making them highly promising for photovoltaic applications with minimal absorption losses. In particular, understanding the intricate interplay between dopants and these structures is crucial for enhancing the NW properties. Contactless optical techniques are suitable for NW characterization, in particular micro-Raman spectroscopy permits the analysis of axial p-n junctions in Si NWs using the Fano asymmetry parameter (q). The micro-Raman scan along the NW allows us to distinguish the n-type segment, the charge-depleted region at the p-n junction, and the p-type segment. Micro-Raman spectroscopy allows contactless estimation of the free carrier concentration, together with structural characterization, and the junction characteristics. Sun, 01 Jan 2023 00:00:00 GMT https://uvadoc.uva.es/handle/10324/75338 2023-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/75237 Daylight Photoluminescence (dPL) has appeared in recent years as a useful tool for the inspection of solar panels, allowing for the identification of several kind of defects with good spatial resolution. The commutation between two states (On and Off) is usually necessary for the filtration of the ambient light. Several practical solutions have been implemented to do this kind of commutation, both electrically or optically. Here we explore in detail the method consisting on the electrical commutation using an electronic device connected in parallel to an adequate number of panels of a string, allowing to inspect the panels during operation, which is contactless once the electrical device is installed. The method can be also applied for the inspection of whole strings, in this case the electronic device is connected in series to the string to be inspected. The advantage of the method is the very fast commutation of the state of the string, between the MPP state and a state at/or very close to OC conditions. The values of the On and Off signals, the process and quality of the images, and the response of the inverter have been checked. Mon, 01 Jan 2024 00:00:00 GMT https://uvadoc.uva.es/handle/10324/75237 2024-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/75218 More efficient and cost effective procedure for large scale daylight EL dEL measurements in PV plants. Pillars of this strategy working during the day without disassembling the modules and without the use of power supplies. An InGaAs camera (model Hamamatsu C 12741 03 640 x 512 pixel) has been used to take the dEL images Sun, 01 Jan 2023 00:00:00 GMT https://uvadoc.uva.es/handle/10324/75218 2023-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/71084 Las perovskitas de haluro mixto, en este caso CsPbIBr2, son las candidatas más destacadas para su uso en la fabricación de células solares de tercera generación por su compromiso eficiencia/estabilidad. En este trabajo se plantea un estudio del proceso de degradación que tiene lugar cuando se somete a dichas perovskitas a luz ultravioleta (325 nm) de forma prolongada, durante 24 h, en condiciones atmosféricas normales. Para ello se analiza su emisión de fotoluminiscencia (PL) durante toda la experiencia. Este análisis va acompañado de un estudio de la morfología de la muestra mediante microscopia electrónica de barrido (SEM) y catodoluminiscencia (CL). Por un lado, se ha obtenido que la muestra presenta una textura granular, con tamaños de grano muy irregulares, presentando una mayor concentración de I en las fronteras de grano. Por otro lado, se ha comprobado que en las primeras fases de la degradación se producen agregados ricos en I. A medida que pasa el tiempo se produce la migración de los haluros, obteniendo, al terminar la experiencia, una fase rica en Br próxima a CsPbBr3. Mon, 01 Jan 2024 00:00:00 GMT https://uvadoc.uva.es/handle/10324/71084 2024-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/71083 Tradicionalmente, la inspección de plantas fotovoltaicas se fundamenta en el examen visual y termográfico de los módulos que las conforman para la detección de posibles defectos. Sin embargo, la creciente asiduidad de fenómenos meteorológicos extremos como son, en particular, las tormentas de granizo, ha generado la necesidad de utilizar otros sistemas para su caracterización más minuciosa y la cuantificación del rendimiento energético de los módulos. Con esto en mente, se evaluó la eficacia de los métodos canónicos y otros más novedosos, como la electroluminiscencia y el trazado de curvas I-V y P-V, mediante el estudio individualizado de un conjunto de módulos fotovoltaicos afectados por una tormenta de granizo y el cotejo de la información que cada una de estas técnicas es capaz de ofrecer. Mon, 01 Jan 2024 00:00:00 GMT https://uvadoc.uva.es/handle/10324/71083 2024-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/71082 En este trabajo se analiza el estado actual de una de las instalaciones fotovoltaicas (FV) más antiguas de España, del año 2006, con una tecnología de paneles y componentes eléctricos/eléctrónicos que ha variado mucho en los últimos años. La instalación, de 100 kWp, consta de paneles de Si monocristalino de 185 Wp, y está conectada a un único inversor, con un único tracker del punto de máxima potencia. La inspección visual de los distintos componentes de la instalación (paneles, estructuras, cableado) se ha complementado con la inspección de los paneles FV mediante técnicas complementarias (curva I-V, termografías y electroluminiscencias diurnas), y se ha chequeado así mismo el estado actual del inversor a través de la medida de su rendimiento y su rango de operación. Se ha observado que la estructura y cableado están en buen estado. Los paneles FV analizados tiene una pérdida media del 23% respecto a la potencia nominal, aunque algunos presentan una degradación mucho más elevada, debido a roturas por impactos. El inversor sigue teniendo un rendimiento muy próximo a su valor inicial para valores de tenisón dentro de su rango. Mon, 01 Jan 2024 00:00:00 GMT https://uvadoc.uva.es/handle/10324/71082 2024-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/71078 This paper presents a comparative study of electroluminescence (EL) imaging of silicon photovoltaic (PV) panels in three currently operating PV plants. EL images were acquired using two methods: in a darkroom with a silicon sensor reflex camera after dismantling the panels; and during daylight without dismantling the panels using an InGaAs sensor camera (dEL). The results demonstrate that dEL can detect the same important defects in the PV panels while being not only less costly in terms of time and money but also able to prevent the production of new defects resulting from disassembly, transportation and reassembly of the modules. This way, dEL provides a more efficient and reliable procedure for quality control and maintenance. Mon, 01 Jan 2024 00:00:00 GMT https://uvadoc.uva.es/handle/10324/71078 2024-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/71077 Daylight Photoluminescence (dPL) has appeared in recent years as a useful tool for the inspection of solar panels, allowing for the identification of several kind of defects with good spatial resolution. The commutation between two states (On and Off) is usually necessary for the filtration of the ambient light. Several practical solutions have been implemented to do this kind of commutation, both electrically or optically. Here we explore in detail the method consisting on the electrical commutation using an electronic device connected in parallel to an adequate number of panels of a string, allowing to inspect the panels during operation, which is contactless once the electrical device is installed. The method can be also applied for the inspection of whole strings, in this case the electronic device is connected in series to the string to be inspected. The advantage of the method is the very fast commutation of the state of the string, between the MPP state and a state at/or very close to OC conditions. The values of the On and Off signals, the process and quality of the images, and the response of the inverter have been checked. Mon, 01 Jan 2024 00:00:00 GMT https://uvadoc.uva.es/handle/10324/71077 2024-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/71076 In this study, we present a robust comparison between EL/dEL images taken with an InGaAs camera, and “golden images” taken under optimal conditions with a Si camera in the dark, which serves as the benchmark. We study the correlation of EL/dEL data quality correlated with the golden image, considering different acquisition parameters and electrical current panel modulations. A key contribution of this work is the correlation of the SNR25 metric, recently introduced by our group, with pixel-by-pixel metrics used to assess image similarity using the Structural Similarity Index (SSIM). Our findings indicate that the quality of dEL images is reliable, showing a satisfactory correlation with data obtained through dark room EL. This analysis was conducted by comparing the structural correlation pixel by pixel (SSIM), demonstrating that dEL data has a very high correlation, indicating that both methods provide the same information about the panel. Furthermore, we found a correlation between the SNR25 metric and the SSIM, allowing us to use this metric as a proxy to assess the quality of the dEL images taken on the field. The results of this research validate the use of dEL imaging for practical applications. Mon, 01 Jan 2024 00:00:00 GMT https://uvadoc.uva.es/handle/10324/71076 2024-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/71075 Electroluminescence imaging is a powerful technique for PV fault diagnosis and for this reason there is a growing interest of the O&M industry to make it widely available for in site inspections instead of randomly choosing samples throughout the PV plant. Few groups in the world disclose methodologies for daylight EL (dEL) image acquisition of installed PV modules, using different equipment and image processing procedures. In this work, we aim to compare methodologies from two research groups that have been working on practical ways to perform robust dEL imaging in parallel. We present the results from acquisitions made with similar but not identical equipment, weather conditions and PV module technologies. Image processing on the same datasets from both laboratories is performed using their own methods, indicating if the image processing methods and approach provide consistent results or not. While each laboratory has developed its own signal-to-noise ratio markers, both present good consistency with signal at an exposure time analysis, but not always a direct correspondence to the image quality. This intercomparison will lead to improvements on each laboratory procedure, expand the discussion to other groups and initiate a discussion on the establishment of dEL image quality and SNR metric baselines. Sun, 01 Jan 2023 00:00:00 GMT https://uvadoc.uva.es/handle/10324/71075 2023-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/71073 Electroluminescence (EL) imaging is a very powerful technique for the identification of defects in Silicon solar cells and panels. Daylight Electroluminescence (dEL) has emerged recently, aiming to avoid the need to perform the EL images on dark environments, which complicates the measurements and limits the number of panels to be inspected. In this work we present a procedure to obtain dEL images by using sinusoidal or square excitations and high speed InGaAs cameras, working in asynchronous mode between excitation and signal capture. We subsequently apply post-processing techniques based on both frequency and time domain analyses to assess the quality of the images by quantifying the signal-to-noise ratio arising from both analyses. We captured a stack of dEL images using two InGaAs cameras capable of acquiring at speeds of up to 60 and 600 frames per second. Our results demonstrate the promising potential of the proposed dEL method, as the post-processed image stack exhibits the same features as dark EL images obtained using the same InGaAs cameras. Notably, this stack of dEL images can be obtained within a very short acquisition time, typically ranging from 100 to 200 ms, while maintaining good image quality. Sun, 01 Jan 2023 00:00:00 GMT https://uvadoc.uva.es/handle/10324/71073 2023-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/66797 Silicon technology has been the cornerstone for the advance of the current age of information since the inception of the first transistor, due to an exponential development of microelectronics and chip miniaturization. Based on this success, some of the emerging technologies in photovoltaics and quantum computing are being developed using silicon nanowires as a fundamental building block. In the case of photovoltaics, p-n axial and core-shell junctions in Si nanowires allow the integration of silicon technology with other materials and thus a potential larger solar cell efficiency [1]. In quantum computing, silicon nanowires serve as one of the semiconducting platforms for qubit development by controlling the electron spin levels using a tailored selected doping and voltage in gates that split the nanowire into different quantum dots [2]. In both scenarios it is of paramount importance to control several key parameters, among them the dopant concentration in the nanowire, the stress, and the concentration of defects. They can all affect the operation of the corresponding device and result in critical failure or lack of reliability. Accessing these parameters with nanoscale resolution has been a challenge for spectroscopic techniques due to the diffraction limit of currently widespread optical spectroscopy. We present here a characterization using micro-Raman imaging and tip-enhanced Raman spectroscopy (TERS) that shows the potential of these techniques to determine the doping profile of silicon nanowires in both p-n junctions and silicon nanostructures for qubits, and to distinguish doping effects from others such as the presence of strain, crystal grains, and defects. High dopant concentrations lead to Fano asymmetric line shape of the Raman spectrum of silicon with an asymmetry parameter proportional to the dopant concentration and character – p- or n-type doping [3]. Confinement of the electric field due to the nanoscale diameter of the nanowires results in an enhancement of the Raman signal that yields higher resolution than that expected without this antenna effect. This enhancement allows us to employ micro-Raman spectroscopy successfully to distinguish several of the above mentioned effects in nanostructures. In the case of p-n axial junctions in silicon nanowires, we observe an asymmetry with higher spectral weight in the low and high energy side for p-type and n-type doping, respectively, being the effect more pronounced in the case of p-type doping. This effect is more significant for doping concentrations above 1017 cm-3. In the case of nanostructured silicon for qubits we observe residual strain and crystallite grain boundaries close to the nanowire, tentatively attributed to the presence of We analyze the Raman spectra employing several asymmetric functions and compare the results obtained in nanowires with those reported in the literature and achieved in bulk silicon as a function of doping. Finally, we employ TERS to reach nanoscale spatial resolution and compare the accuracy and limitations of micro-Raman in the determination of the doping profile. Sun, 01 Jan 2023 00:00:00 GMT https://uvadoc.uva.es/handle/10324/66797 2023-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/66796 The use of semiconductor technologies for the development of qubits is having a strong development. This paper reports the development of technological solutions to enable the experimentation on semiconductor qubits. Two technological approaches are followed: spin qubits in quantum dots and Majorana qubits for topological quantum computing. This is complemented by research on advanced characterization of the fabricated qubit nanostructures. Sun, 01 Jan 2023 00:00:00 GMT https://uvadoc.uva.es/handle/10324/66796 2023-01-01T00:00:00Z