TY - JOUR A1 - Schulze, Achim A1 - Koentopp, M. B. A1 - Taubitz, C. T1 - A drift and diffusion model for PID-s in solar modules JF - IEEE Journal of Photovoltaics N2 - A quantitative physical model for potential induced degradation of the shunting type (PID-s) in solar modules is introduced. Based on a drift and diffusion approach for sodium ions and atoms, it gives insight into the kinetics of degradation and the corresponding regeneration. A simple drift/source term is used to describe the time-dependent flux of Na-ions towards stacking faults at the surface of the solar cell. The assumed transport mechanism for Na+ ions through the SiN-layer uses the modified Stern-Eyring rate theory but our approach can also be adapted to other mechanisms. Several PID-s and regeneration curves of one-cell solar modules at T = 49°C and T = 90°C with 1000V potential difference between modul frame and cell were measured and least-square fits of the in-situ measured parallel resistance Rsh to the model were performed giving very good accordance. Based on a few measurements, the model can predict PID-s and regeneration characteristics of solar modules under different conditions. KW - Photovoltaic cells, Photovoltaic systems, PID Y1 - 2020 UR - https://doi.org/10.1109/JPHOTOV.2020.3003776 VL - 2020 PB - IEEE CY - USA ER - TY - CHAP A1 - Schneider, S. A1 - Hüttl, B. A1 - Pflaum, D. A1 - Schnell, V. A1 - Schulze, Achim T1 - Freifeldcharakterisierung von PV-Anlagen im Rahmen des Projektes PV- FeldLab -ein Statusbericht- T2 - 3. Regenerative Energietechnik Konferenz in Nordhausen N2 - Das Projekt PV-FeldLab verfolgt das Ziel, ein umfassendes Konzept für eine messtechnisch sehr präzise elektrische Freifeld-Charakterisierung von PV-Generatoren zu entwickeln. Es beinhaltet eine optische Untersuchung mittels drohnengestützter Thermografie und eine genaue elektrische Charakterisierung von PV-Anlagen im Freifeld, auch bei räumlicher Inhomogenität von Bestrahlungsstärke, Temperatur und bei variablen Aufbauwinkeln von Modulen im Strang. Die Verknüpfung der elektrischen und optischen Messdaten erlaubt eine effiziente Untersuchung von PV-Anlagen und ermöglicht eine Präzisierung von Ertragsanalysen. Dieser Bericht beschreibt den ersten Projektabschnitt, in welchem der Fokus vor allem auf der Initialisierung der messtechnischen Komponenten, sowie ersten Messungen und Analysen liegt. KW - Photovoltaik, Messtechnik, Charakterisierung von Solarmodulen Y1 - 2020 PB - RET.con 2020 CY - Nordhausen ER - TY - JOUR A1 - Hüttl, Bernd A1 - Gottschalk, L. A1 - Schneider, S. A1 - Pflaum, D. A1 - Schulze, Achim T1 - Accurate Performance Rating of Photovoltaic Modules under Outdoor Test Conditions JF - Solar Energy N2 - Outdoor performance analyses of photovoltaic modules can be advantageous compared to indoor investigations, as they take into account the influences of natural test conditions on the modules. However, such outdoor performance assessments usually suffer from poor accuracies due to undefined test conditions for the modules. This paper reports on a comprehensive concept for improved outdoor analysis which results in performance data with indoor laboratory precision. The approach delivers current-voltage characteristics for even more test conditions than required by the standard IEC 61853-1. Hence, curves of modules’ electrical parameters above irradiance can be deduced for any temperatures. The concept allows precise determination of temperature coefficients for user-defined irradiances taking into account outdoor effects like light-soaking or light-induced degradation. The calibration and measurement uncertainty of the presented outdoor analysis method is evaluated quantitatively. For the measurements an advanced outdoor set-up was used. KW - Photovoltaic systems, Metrology Y1 - 2019 UR - https://doi.org/10.1016/j.solener.2018.12.002 VL - 2019 IS - 177 SP - 737 EP - 745 ER - TY - CHAP A1 - Schneider, S. A1 - Hüttl, B. A1 - Gerstenberg, L. A1 - Wesselak, V. A1 - Voswinckel, S. A1 - Schulze, Achim T1 - PV-FeldLab -Feldlabor für Vorort-Leistungsbestimmungen und Alterungsidentifikation von Photovoltaikgeneratoren T2 - 2. Regenerative Energietechnik Konferenz in Nordhausen N2 - Ziel des Projektes ist es, ein Verfahren für elektrische Vorort-Leistungsanalysen von Photovoltaik (PV)-Anlagen zu entwickeln. Dazu werden die elektrischen Parameter von PV-Strings lokal und global mit Hilfe eines neuen Feldlaboransatzes mit Indoor-Laborgenauigkeit vermessen. Das neue Messverfahren ist normgerecht und wird helfen, die Standardisierung von Feldmessungen weiterzuentwickeln. Im Projekt werden bekannte Messmethoden der Photovoltaik, (IR-Thermografie, I-U-String-Messung, digitale Datenverarbeitung mittels Selbstreferenzierung) zu einem innovativen Gesamtkonzept synthetisch zusammengeführt. Die Entwicklung des Messverfahrens wird an speziell gealterten PV-Anlagen marktbestimmender Technologien (c-Si-, CdTe-, CIGS-Muster-PV-Anlagen) vorangetrieben. So wird das Verfahren auf Erkennung spezifischer Degradationsszenarien und marginaler quantitativer Parameterveränderungen trainiert und geschärft KW - Photovoltaik, Messtechnik, Charakterisierung von Solarmodulen Y1 - 2019 PB - RET.com 2019 CY - Nordhausen ER - TY - CHAP A1 - Schneider, S. A1 - Pflaum, D. A1 - Gottschalk, L. A1 - Schulze, Achim A1 - Hüttl, B. T1 - Laborgenaue elektrische Charakterisierungen von PV-Modulen unter Feldbedingungen T2 - 1. Regenerative Energietechnik Konferenz in Nordhausen N2 - Outdoor-I-U-Messungen an Photovoltaik- (PV) - Modulen haben den Vorteil, dass Effekte wie „light soaking“ oder „light-induced degradation“ unter natürlichen Bedingungen untersucht werden können. Solche Outdoor-Analysen können unter Anwendung des Selbstreferenzierungsalgorithmus (SRA) die Zuverlässigkeit von Indoor-Flasher-Messungen erreichen. Dieses neue Konzept liefert I-UEigenschaften für wesentlich mehr Testbedingungen als vom Standard IEC 61853 gefordert und so können Schwachlichtkurven aller relevanten elektrischen I-U-Parameter für bestimmte Temperaturen erzeugt werden. Wir berichten über experimentelle Ergebnisse einer 6-tägigen Outdoor-Messkampagne an Dünnschicht-PV-Modulen. Wir evaluieren darüber hinaus die Möglichkeiten, Temperaturkoeffizienten, STC- und NOCT-Daten zu bestimmen und I-U-Kennlinien als Basis für Fitting-Analysen abzuleiten. Abschließend wird die Genauigkeit der neuen Outdoor-Methode untersucht. KW - Photovoltaik, Messtechnik, Charakterisierung von Solarmodulen Y1 - 2018 PB - RET.con 2018 CY - Nordhausen ER - TY - CHAP A1 - Hüttl, B. A1 - Heimfarth, J.P. A1 - Schulze, Achim A1 - Schelhase, S. A1 - Hafemeister, M. A1 - Weiler, U. A1 - Queck, M. A1 - Patzlaff, T. A1 - Bauer, M. A1 - Becker, F. T1 - Improved JV-Analysis on CdTe Dot Cells by Controlled Series Resistance T2 - Proc. 27th European Photovoltaic Solar Energy Conference and Exhibition N2 - CdS/CdTe thin film solar technology is one of the most promising concepts to accomplish high efficiencies and low costs in mass production. Further knowledge about electric parameters, such as serial resistances and recombination losses, is needed in order to improve in a systematic approach the module efficiency. The basic tool for device evaluation is the JV-measurement (current density – voltage) under standard test conditions. JVmeasurements result in rather direct determination of electric parameters, and detailed JV-analysis in indirect determination of some more relevant electric parameters. For thin film solar cells the usual 2-diode model and the responsible equation can be reduced to a 1-diode model due to significant recombination processes in the space charge region. However, the fit results suffer on imprecision of derived recombination currents (Jrec), and series resistance (Rs), due to their ambiguousness in fit routine. Direct and precise access of Rs by measurements fails for CdTe, due to its significant dependency on illumination levels. In this work we present a new method for precise Rs and Jrec determination of CdTe cells. KW - CdTe, CIS and Related Ternary and Quaternary Thin Film Solar Cells Y1 - 2012 PB - 27th European Photovoltaic Solar Energy Conference and Exhibition ER - TY - CHAP A1 - Hüttl, B. A1 - Wachter, M. A1 - Gottschalk, L. A1 - Schulze, Achim A1 - Becker, F. T1 - Self Reference Algorithm for Precise Outdoor Characterization of PV Modules T2 - PV-Days Halle 2016 N2 - Outdoor or just on site analyzes of photovoltaic modules can offer some advantages in comparison to indoor Lab stud-ies. In this way the electrical performance is monitored and logged under natural operating conditions in full range of irradiation and temperature. The entirety of monitored IV data allows deriving low-light characteristics of electric parameters, temperature coefficients and root cause analysis for possible degradation. We apply so-called self-reference algorithm in order to increase the accuracy of analysis. The improved precision is due to application of effective acting irradiation and effective temperature instead of externally measured data. Effective irradiation is determined in self-referencing scheme: the short circuit current of the module is assigned to the irradiation. KW - Photovoltaic systems, Metrology, Solar Modules Y1 - 2016 PB - PV-Days Halle 2016 CY - Halle ER - TY - CHAP A1 - Wachter, M. A1 - Gottschalk, L. A1 - Simmler, M. A1 - Schulze, Achim A1 - Becker, F. A1 - Sayala, M. A1 - Hüttl, B. T1 - Short Circuit Current Measurements at Clear-Sky Conditions on Photovoltaic Modules: Basic for a Reliable Self-Reference Algorithm T2 - Proc. 32nd European Photovoltaic Solar Energy Conference and Exhibition (PVSEC) N2 - Outdoor or just on site analyzes of photovoltaic modules can offer some advantages in comparison to indoor Lab studies. In this way the electrical performance is monitored and logged under natural operating conditions in full range of irradiation and temperature. The entirety of monitored IV data allows deriving low-light characteristics of electric parameters, temperature coefficients and root cause analysis for possible degradation. We apply so-called self-reference algorithm in order to increase the accuracy of analysis. The improved precision is due to application of effective acting irradiation and effective temperature instead of externally measured data. Effective irradiation is determined in self-referencing scheme: the short circuit current of the module is assigned to the irradiation. This assignment has to be calibrated, preferably at standard test conditions for irradiation. In this contribution we demonstrate a process of precise measurement of Isc under clear-sky outdoor conditions and the determination of the short circuit current for STC. The measurement method avoids errors by spectral deviations with respect to AM 1.5G spectrum, by optical reflection losses for high angles of incidence and errors by high albedo impact. In particular we investigate comparatively a CdTe module under outdoor conditions and by means a calibrated indoor Lab flasher. KW - Photovoltaic systems, Metrology, Solar Modules Y1 - 2016 PB - 32nd European Photovoltaic Solar Energy Conference and Exhibition (PVSEC) ER - TY - CHAP A1 - Schulze, Achim A1 - Panuysen, Markus A1 - Daume, Darwin A1 - Schönau, Maximilian T1 - Quantitative Shade Detection for PV-Systems based on Clearsky Data T2 - Proceedings of the 41st EU PVSEC N2 - In modern monitoring applications, losses from shading should be quantitatively separated from other loss mechanisms such as soiling, degradation or total failures. Based on clearsky reference data, we introduce a shading matrix which enables accurate hourly description of shading losses of PV strings over the year. This matrix can be used to improve failure detections and reference yield data in PV systems. Furthermore, a shading matrix with respect to sun position is introduced to improve the spatial understanding of shading caused by surrounding objects. KW - Photovoltaic Systems KW - Shading KW - Failure Detection Y1 - 2024 ER - TY - CHAP A1 - Schönau, Maximilian A1 - Daume, Darwin A1 - Panhuysen, Markus A1 - Kreller, T. A1 - Jachmann, J. A1 - Schulze, Achim A1 - Hüttl, Bernd A1 - Landes, Dieter T1 - Hindcasting Solar Irradiance by Machine Learning using Photovoltaic Data T2 - Proceedings of the 41st EU PVSEC N2 - This work introduces an innovative approach to calculate high-accuracy solar irradiance data for effective asset management of photovoltaic plants using Machine Learning. Ground-based pyranometers are expensive and seldom maintained, while weather service providers face limitations in spatial and temporal accuracy. A novel irradiance data model is introduced, that combines satellite weather information with data from PV plants to reconstruct historical irradiance levels with high accuracy. Our method uses existing PV arrays as "virtual sensors" to capture the local operating conditions, specifically the local irradiance incident on the array. The model was developed and validated using data from 43 medium to large-scale PV plants and two high-precision irradiance sensors. Results show superior performance compared to satellite weather data. With a root mean square deviation of 71 W/m² for global horizontal irradiation and 133 W/m² for direct normal irradiation with 5-minute resolution data, the model is about three times as accurate as the satellite weather prediction. This approach offers significant advantages in spatial resolution, reliability, and cost-effectiveness over conventional irradiance data by satellites or sensors. Utilizing SMARTBLUE AG'S dense network of thousands of monitored PV plants, the proposed methodology will enable the accurate prediction of irradiance in Germany, significantly enhancing asset management capabilities for PV plants. KW - Solar Irradiance KW - Photovoltaic KW - Hindcasting KW - Machine Learning Y1 - 2024 ER - TY - CHAP A1 - Schönau, Maximilian A1 - Daume, Darwin A1 - Panhuysen, Markus A1 - Schulze, Achim A1 - Hüttl, Bernd A1 - Landes, Dieter T1 - Verbesserte Clear-Sky-Erkennung durch hybrides Maschinelles Lernen T2 - Proceedings of the 7th Ret.Con, Nordhausen N2 - Die präzise Erkennung von Clear-Sky-Momenten ist für die Überwachung und Effizienzana-lyse von Photovoltaikanlagen von zentraler Bedeutung, da zu diesen Zeitpunkten definierte und model-lierbare Einstrahlungsverhältnisse herrschen. Es wird ein hybrides Modell zur verbesserten Erkennung von Clear-Sky-Momenten auf Basis von Einstrahlungsdaten vorgestellt. Hierfür wurden zunächst ma-nuell, dann mithilfe eines CNNs Merkmale aus den Einstrahlungsdaten gebildet. Eine Falls tudie mit Referenzdaten belegt, dass durch die Kombination dieser wissens-und datengetriebenen Methoden Clear-Sky-Momente zuverlässiger identifiziert werden können. Dadurch können Analysemethoden schneller und zuverlässiger Aussagen über die untersuchten PV-Anlagen treffen. KW - Clearsky KW - Photovoltaik Y1 - 2024 ER - TY - JOUR A1 - Schönau, A1 - Panhuysen, A1 - Sonntag, A1 - Banse, A1 - Seel, A1 - Jachmann, A1 - Schulze, Achim A1 - Hüttl, A1 - Landes, T1 - String outages in photovoltaic plants JF - Renewable Energies N2 - In this work, the factors leading to string outages are examined, and an enhanced method for detecting faults at the sub-string level is presented. Utilizing GPT4-o to analyze O&M reports of 5089 photovoltaic plants, we classified outages according to the affected components and the underlying origin, identifying the most frequent string fault causes. An approach employing CUSUM Charts is introduced to identify substring outages within PV systems effectively. The methodology utilizes fundamental field data that is commonly available in practice. A filtering approach, combined with the use of CUSUM control charts, minimizes false positives, ensuring that only consistent underperformance is flagged as an out-age. The methodology returns far fewer false positives and more stable error intervals for substring outages than a former monitoring approach. Overall, the study demonstrates a significant improvement in detecting substring outages. The advanced methodology enables more effective O&M for PV plants, where substring outages are reliably identified after a short detection time. KW - Photovoltaic Systems Y1 - 2025 U6 - https://doi.org/10.1177/27533735251347879 VL - 3 IS - 1 PB - Sage ER - TY - GEN A1 - Schönau, Maximilian A1 - Schönau, Elisabeth A1 - Daume, Darwin A1 - Panhuysen, Markus A1 - Schulze, Achim A1 - Hüttl, Bernd A1 - Landes, Dieter T1 - Improved Sampling of IV Measurements T2 - Proceedings of the 41st EU PVSEC N2 - The measurement of IV curves is the most important characterization technique of photovoltaic devices. This work seeks to determine a fair sampling rate for IV curves. Traditional sampling methods, such as using equidistant voltage steps, result in biased data by over- and undersampling the measurement at different voltages, which affect critical evaluations such as maximum power point (MPP) determination as well as series and shunt resistance estimation. Therefore, an adaptive sampling approach based on calculating the arc length of the IV curve is proposed, aiming to distribute data points equidistantly along the curve. This method is intended to provide a more balanced representation of the measurement data across all segments of the curve. The results indicate that using this adaptive approach, the measurement points can be significantly reduced at lower voltages while maintaining essential data density at key characteristics such as the MPP, facilitating faster and more accurate assessments. KW - Measurement KW - Solar Modules Y1 - 2024 U6 - https://doi.org/10.4229/EUPVSEC2024/3AV.3.50 PB - Proceedings of the 41st EU PVSEC ER -