Electricity from photovoltaic solar cells: Flat-Plate Solar Array Project final report. Volume VI: Engineering sciences and reliability

The Flat-Plate Solar Array (FSA) Project, funded by the U.S. Government and managed by the Jet Propulsion Laboratory, was formed in 1975 to develop the module/array technology needed to attain widespread terrestrial use of photovoltaics by 1985. To accomplish this, the FSA Project established and managed an Industry, University, and Federal Government Team to perform the needed research and development. This volume of the series of final reports documenting the FSA Project deals with the Project's activities directed at developing the engineering technology base required to achieve modules that meet the functional, safety and reliability requirements of large-scale terrestrial photovoltaic systems applications. These activities included: (1) development of functional, safety, and reliability requirements for such applications; (2) development of the engineering analytical approaches, test techniques, and design solutions required to meet the requirements; (3) synthesis and procurement of candidate designs for test and evaluation; and (4) performance of extensive testing, evaluation, and failure analysis to define design shortfalls and, thus, areas requiring additional research and development. During the life of the FSA Project, these activities were known by and included a variety of evolving organizational titles: Design and Test, Large-Scale Procurements, Engineering, Engineering Sciences, Operations, Module Performance and Failure Analysis, and at the end of the Project, Reliability and Engineering Sciences. This volume provides both a summary of the approach and technical outcome of these activities and provides a complete Bibliography (Appendix A) of the published documentation covering the detailed accomplishments and technologies developed

Procedure for the quantification of the degradation index of Photovoltaic Generators

A procedure is presented for the quantification of the degradation index of Photovoltaic Generators, based on the quantification of the operational losses inherent in the system, which allows maintaining the nominal operating conditions and by the warranty terms of the photovoltaic generator. A photovoltaic generator connected to the network with a nominal power of 7.5 kWp, installed in the Solar Energy Research Center of Santiago de Cuba, is used to evaluate and validate the procedure. The starting point is the mathematical model of the photovoltaic generator, then the operational losses of the photovoltaic generator are quantified and the mathematical model is adjusted to real conditions, through a polynomial adjustment.  The results obtained show that the photovoltaic generator presents deviations in terms of the nominal power generation, because the operational losses are 7% with respect to the values ​​given by the manufacturer

Flat-plate solar array project. Volume 6: Engineering sciences and reliability

The Flat-Plate Solar Array (FSA) Project activities directed at developing the engineering technology base required to achieve modules that meet the functional, safety, and reliability requirements of large scale terrestrial photovoltaic systems applications are reported. These activities included: (1) development of functional, safety, and reliability requirements for such applications; (2) development of the engineering analytical approaches, test techniques, and design solutions required to meet the requirements; (3) synthesis and procurement of candidate designs for test and evaluation; and (4) performance of extensive testing, evaluation, and failure analysis of define design shortfalls and, thus, areas requiring additional research and development. A summary of the approach and technical outcome of these activities are provided along with a complete bibliography of the published documentation covering the detailed accomplishments and technologies developed

A review of key environmental and energy performance indicators for the case of Renewable Energy Systems when integrated with storage solutions.

During the last years a variety of numerical tools and algorithms have been developed aiming at quantifying and measuring the environmental impact of multiple types of energy systems, as those based on Renewable Energy Sources. Plenty of studies have proposed the use of a Life Cycle Assessment methodology, to determine the environmental impact of renewable installations when coupled with storage solutions, based on a pre-selected repository of Key Performance Indicators. The main scope of this paper is to propose a limited number of best fitting, and at the same time easily adaptable to various configurations, list of KPIs for the case of renewable energy systems. This is done by capitalizing on the environmental and energy performance KPIs tracked in the open literature (e.g. “Global Warming Potential”, “Energy Payback Time”, “Battery Total Degradation”, “Energy Stored on Invested”, “Cumulative Energy Demand”) and/or other proposing new simple, scalable and adaptable ones, (e.g. “Embodied Energy for Infrastructure of Materials and for the building system”, “Life Cycle CO2 Emissions”, “Reduction of the Direct CO2 emissions”, “Avoided CO2 Emissions”, “CO2 equivalent Payback Time”). Moreover, the proposed KPIs are distributed according to the individual phases of the entire life-cycle of a related component of a renewable energy system, each time the environmental impact refers to, i.e. manufacturing, operational and end-of-life. Apart from that, the current paper presents a necessary base grounded approach, which can be followed for a holistic approach in environmental point of view of renewable-based technologies, by addressing the potential competing interests of the relevant stakeholders (e.g. profit for the market operator in contrast to low-cost services for the consumer). All in all, the scalar quantification of the environmental impact of multiple energy systems, through a list of proposed assessment criteria, being evaluated in terms of the selected repository of KPIs, enables the comparison on a fair basis of the available energy systems, irrespective if they are fossil-fuel or RES based ones. As a typical example, a simple standard model of a photovoltaic integrated with an electric battery is selected, for which indicative indicators are provide

Comparación del desempeño de indicadores eléctricos para la detección de PID en paneles fotovoltaicos

La degradación inducida por potencial (PID) en paneles solares fotovoltaicos (FV) se produce debido a su operación en cadenas que hacen parte de grandes instalaciones, y bajo ciertas condiciones operativas de voltaje y ambientales, especialmente humedad y temperatura. El PID puede ocasionar hasta un 40 % de disminución en la capacidad de potencia generada del panel FV, y en los casos más severos la terminación de su vida útil. Cuando este fenómeno se detecta a tiempo, las causas se pueden corregir y el efecto en los paneles FV podría ser susceptible a un proceso de reversibilidad. Este artículo presenta un análisis comparativo del desempeño de cuatro indicadores eléctricos para detectar el PID reportados en la literatura reciente. Este estudio se realiza mediante simulación, utilizando el modelo de un solo diodo para representar el comportamiento del panel FV, y bajo diferentes condiciones de irradiancia y temperatura. Los resultados encontrados demuestran ventajas de un indicador basado en la resistencia paralelo normalizada, en cuanto a su practicidad y baja sensibilidad ante cambios en las condiciones de irradiancia y temperatura.Potential-induced degradation (PID) in photovoltaic (PV) solar panels occurs due to the operation in strings that are part of large installations, and under determinate voltage and environmental operating conditions, especially humidity and temperature. The PID can cause decreasing of up to 40 % in the generated power capacity of the PV panel and, in the most severe cases, the end of its lifetime. When this phenomenon is detected in time, the causes can be corrected and, the effect on the PV panels could be susceptible to a reversibility process. This article presents a comparative analysis of the performance of four electrical indicators to detect PID reported in recent literature. This study is carried out by simulation, using the single-diode model to represent the PV panel, and under different irradiance and temperature conditions. The results show the advantages of an indicator based on normalized parallel resistance, in terms of its practicality and low sensitivity to changes in irradiance and temperature conditions

Monitoring PV systems : a recommendation for appropriate measurement to improve system longevity

Solar photovoltaic (PV) systems demand improved operation and maintenance (O&M) measures to increase system longevity and overall performance. Installation of solar PV systems are rapidly increasing, and while technology is improving, O&M measures are neglected or poorly understood. Appropriate O&M will improve solar PV market competitiveness. This study aims to design requirements for operators to provide necessary information to perform an analysis of the state of the system. Building on existing literature for monitoring PV system, it asks: Which parameters and indicators are necessary to evaluate the state of the system, which quality assessments must be made to produce reliable results, and what must operators do the first year to aid this process? Based on literature regarding monitoring and maintenance of solar PV, an analysis was performed on the operational data set from the PV system at Glava Energy Center in Glava, Sweden. The methodology was based on CRISP-DM and was exploratory. Data were analysed, enhanced, and analysed further in the context of Overall Equipment Effectiveness. The approach was adjusted as understanding grew. The results provide insights into the parameters, indicators and the general quality of data. Temperature and plane-of-array irradiance is suggested as the most influential parameters to evaluate system projections, although the parameters should be accompanied by other measurements. There are also presented an analysis of the quality of the data set. The quality is periodically low, which leads to recommendations regarding maintaining quality of monitoring of the PV system.Solcelle fotovoltaiske systemer krever forbedrede tiltak for drift- og vedlikehold (O&M) for å øke systemets levetid og generelle ytelse. Installasjonen av solcelleanlegg øker raskt, og mens teknologien forbedrer seg, er O&M-tiltak neglisjert eller dårlig forstått. Passende O&M vil forbedre konkurranseevnen til PV. Denne studien tar sikte på å utforme krav til operatører til å gi nødvendig informasjon for å utføre en analyse av systemets tilstand. På bakgrunn av eksisterende litteratur for overvåking av PV-system spør den: Hvilke parametere og indikatorer er nødvendige for å evaluere tilstanden til systemet, hvilke kvalitetsvurderinger som må gjøres for å gi pålitelige resultater, og hva må operatørene gjøre det første året for å hjelpe denne prosessen? Basert på litteratur om overvåking og vedlikehold av solcelleanlegg, ble det utført en analyse av driftsdatasettet fra PV-systemet ved Glava Energy Center i Glava, Sverige. Metodikken var basert på CRISP-DM og var utforskende. Data ble analysert, forbedret og analysert videre. Tilnærmingen ble justert etter hvert som forståelsen vokste. Resultatene gir innsikt i parameterne, indikatorene og den generelle kvaliteten på data. Temperatur og plan-av-array-irradians foreslås som de mest innflytelsesrike parameterne for å evaluere systemframskrivninger, selv om parameterne bør ledsages av andre målinger. Det blir også presentert en analyse av kvaliteten på datasettet. Kvaliteten er periodisk lav, noe som fører til anbefalinger om opprettholdelse av kvaliteten på overvåkingen av PV-systemet.M-I

Fault Diagnostic Methodology for Grid-Connected Photovoltaic Systems

This research focuses on the design of a fault diagnosis methodology to contribute to the improvement of efficiency, maintainability and availability indicators of Grid-Connected Photovoltaic Systems. To achieve this, we start from the study of the mathematical model of the photovoltaic generator, then, a procedure is performed to quantify the operational losses of the photovoltaic generator and adjust the mathematical model of this to the real conditions of the system, through a polynomial adjustment. A real system of nominal power 7.5 kWp installed in the Solar Energy Research Center of the province of Santiago de Cuba is used to evaluate the proposed methodology. Based on the results obtained, the proposed approach is validated to demonstrate that it successfully supervises the system. The methodology was able to detect and identify 100% of the simulated failures and the tests carried out had a maximum false alarm rate of 0.22%, evidencing its capacity

A comprehensive study of diagnosis faults techniques occurring in photovoltaic generators

Recently, many focuses have been done in the field of renewable energies, especially in solar photovoltaic energy. Photovoltaic generator, considered as the heart of any photovoltaic installation, exhibits sometimes malfunctions which involve degradations on the overall photovoltaic plant. Therefore, diagnosis techniques are required to ensure failures detection. They avoid dangerous risks, prevent damages, allow protection, and extend their healthy life. For these purposes, many recent studies have given focuses on this field. This paper summarizes a large number of such interesting works. It presents a survey of photovoltaic generator degradations kinds, several types of faults, and their major diagnosis techniques. Comparative studies and some critical analyses are given. Other trending diagnosis solutions are also discussed. A proposed neural networks-based technique is developed to clarify the main process of diagnosis techniques, using artificial intelligence. This method shows good results for modelling and diagnosing the healthy and faulty (shaded) photovoltaic array

Measurement techniques and instruments suitable for life-prediction testing of photovoltaic arrays

Array failure modes, relevant materials property changes, and primary degradation mechanisms are discussed as a prerequisite to identifying suitable measurement techniques and instruments. Candidate techniques and instruments are identified on the basis of extensive reviews of published and unpublished information. These methods are organized in six measurement categories - chemical, electrical, optical, thermal, mechanical, and other physicals. Using specified evaluation criteria, the most promising techniques and instruments for use in life prediction tests of arrays were selected