Photovoltaic Module Reliability Workshop 2010: February 18-19, 2010

NREL's Photovoltaic (PV) Module Reliability Workshop (PVMRW) brings together PV reliability experts to share information, leading to the improvement of PV module reliability. Such improvement reduces the cost of solar electricity and promotes investor confidence in the technology--both critical goals for moving PV technologies deeper into the electricity marketplace

Análisis, caracterización y modelado del comportamiento en exterior de módulos de concentración fotovoltaica

[ES] En la presente Tesis Doctoral se ha profundizado en el estudio y análisis del comportamiento eléctrico en exterior de módulos de tecnología de concentración fotovoltaica (CPV), así como en la dependencia de dicho comportamiento con las condiciones ambientales registradas. Entre ellas, para evaluar el comportamiento eléctrico de los módulos CPV, se han considerado: la irradiancia normal directa (DNJ), la distribución espectral de la irradiancia incidente -a través de dos índices alternativos: average photon energy (APE) y spectral matching ratio (SMR)-, la temperatura ambiente (Tamb) Y la velocidad del viento (Ws). A lo largo de esta Tesis Doctoral se han propuesto dos modelos de predicción de la potencia máxima entregada por los módulos CPV apoyándose en polinomios de regresión y técnicas de regresión lineal múltiple. Asimismo, se han implementado dos modelos basados en la utilización[EN] The present PhD goes in depth in the study and analysis of the outdoor electrical performance presented by CPV modules, as well as in the dependence of this performance on the registered environmental conditions. Among them, when evaluating the electric performance of CPV modules, the following variables were considered: direct normal irradiance (DNJ), spectral distribution of the incident irradiance- through two alternative indexes: average photon energy (APE) and spectral matching ratio (SMR)-, ambient temperature (Tamb) and wind speed (Ws). Along this Thesis two different models based on polynomic regression and multiple linear equations, have been proposed to predict the maximum power delivered by the CPV modules. Furthermore, two models based on the use of artificial neural networks have been implemented. These models permit simulating the entire I-V curve of CPV modules.Tesis Univ. Jaén. Departamento de Ingeniería Electrónica y Automática, leída el 16 de julio de 201

Development of a spectral dependent electrical & thermal model for high concentrating photovoltaic (HCPV) receivers

High concentrating photovoltaic (HCPV) systems employ III-V multijunction (MJ) solar cells. Such solar cells are monolithically connected in-series and therefore present a strong dependence on the solar spectrum variations. In addition, the concentrated solar flux contributes to the heat generation within the solar cells and, in combination with the current mismatch between the subcells, can force the device to operate in elevated temperatures. It is important therefore, to investigate the influence of the atmospheric parameters on the electrical performance of HCPV and also to quantify the cooling requirements based on the spectrum changes. In this thesis, a spectral dependent electrical model has been developed to calculate the electrical characteristics and quantify the heat power of a multijunction solar cell. A three-dimensional finite element analysis is also used to predict the solar cell's operating temperature and cooling requirements for a range of ambient temperatures. The combination of these models improves the prediction accuracy of the electrical and thermal behaviour of triple-junction solar cells. The convective heat transfer coefficient between the back-plate and ambient air is quantified based on input spectra. A theoretical investigation is performed to analyse the influence of air mass (AM), aerosol optical depth (AOD) and precipitable water (PW) on the performance of each subcell and whole. It has been shown that the AM and AOD have a negative impact on the spectral and electrical performance of 3J solar cells while the PW has a positive effect, although, to a lesser degree. In order to get a more realistic assessment and also to investigate the effect of heat transfer coefficient on the annual energy yield, the methodology is applied to four US locations using data from a typical meteorological year (TMY3). The integrated modelling procedure is validated experimentally using field measurements from Albuquerque, NM. The importance of the effect of atmospheric parameters on the solar spectrum and hence the performance of HCPV systems is highlighted in this work. The outdoor characterisation provides with useful insight of the influence of spectrum on the performance of a HCPV monomodule and the current CSOC and CSTC ratings are evaluated based on different spectral filtering criteriaESPR

New trends in photovoltaic economy and development of a different technological spectral approach in concentrator photovoltaics

[ES] La energía fotovoltaica basada en el silicio posee una madurez tecnológica fruto de años de experiencia, aunque actualmente existe un punto de inflexión en su desarrollo debido a los límites teóricos de eficiencia. Por ello, se necesitan nuevos enfoques y aplicaciones. Los nuevos enfoques van encaminados al concepto de autoconsumo, donde el usuario se convierte en productor de su electricidad. Aunque la paridad de red es una realidad en España, se propone un modelo de cálculo económico adaptado a los perfiles de consumo y a las tarifas eléctricas existentes, donde se aprecia que dicha paridad podrá no ser totalmente rentable. En cuanto a las aplicaciones alternativas está la Concentración Solar Fotovoltaica, donde una línea de investigación recae en la profundización del estudio de la sensibilidad y limitación de las células de alta eficiencia al espectro solar. Esta tesis realiza una contribución tecnológica mediante el desarrollo de un prototipo que mide la subcélula limitante en estos dispositivos fotovoltaicos multiunión.[EN]The photovoltaic energy based on Silicon has a technological maturity as a result of years of experience, but nowadays there is an inflection point regarding the continuity of its development which is related to its proximity to the maximum theoretic efficiency. Therefore new approaches and applications are necessary. The new approaches are focused on the self-consumption concept, where the enduser turns into an electricity producer. Despite the feasibility of the grid-parity in Spain, a new economic calculus methodology is proposed based on the consumption profiles and the electricity tariffs, where cases of non-profitability will be detected. Regarding the technological alternatives, the Concentrated Photovoltaic appears. One of the research lines falls on the further study of the sensitivity and limitation of the high-efficiency solar cells regarding the solar spectrum. The technological contribution in this thesis is the development of an experimental setup capable of measuring the Iimiting subcell in these multijunctions devicesTesis Univ. Jaén. Departamento de Ingeniería Electrónica y Automática, leída 3 de julio de 201

Photovoltaic Module Reliability Workshop 2011: February 16-17, 2011

NREL's Photovoltaic (PV) Module Reliability Workshop (PVMRW) brings together PV reliability experts to share information, leading to the improvement of PV module reliability. Such improvement reduces the cost of solar electricity and promotes investor confidence in the technology--both critical goals for moving PV technologies deeper into the electricity marketplace

Development and study of a dense array Concentration PhotoVoltaic (CPV) system

In the past several years there has been a growing commercial interest in Concentration PhotoVoltaics (CPV) thanks to its promise of low cost electrical power generation. While the technology of CPV using point-focus Fresnel-like optical elements is reaching maturity, the systems based on dense array receivers still need further scientific progress. This thesis explores the field of CPV applied to a parabolic concentrator prototype and to a dense array receiver made of multijunction solar cells. The solar concentrator, completely designed and built at the University of Trento, is characterized, in order to get the illumination distribution on the PV receiver. The non-uniformity in incident flux results in a current mismatch among cells and strongly impacts the system performance. In order to solve this issue, we have proposed a new type of electrical connection by fitting each cell of the array with an individual DC-DC converter. This method is shown to increase the power transfer efficiency with respect to classical series connection, at least for the tested illumination levels and unbalances. The other main problem with dense array systems is the reliability of the PV receiver, with special attention to the high thermal flux to be dissipated. Several types of water-cooled receivers have been built, with different material configurations that were previously studied with 3D thermal modeling. In particular the building of a multi-cell receiver has required the design of the insulation/interconnection between the cells, the tuning of the cell soldering and the realization of front contact connections

Evaluación y desarrollo de técnicas para la caracterización de sistemas fotovoltaicos a sol real

La obtención de la curva característica Corriente-Tensión (I-V) de un dispositivo fotovoltaico es el experimento esencial que permite obtener la mayor información sobre su comportamiento. A lo largo de esta Tesis Doctoral se ha pretendido aportar soluciones a las principales limitaciones de los actuales sistemas de caracterización FV comerciales. Como resultados más destacados, indicar que se han desarrollado dos sistemas abiertos y fácilmente reproducibles por la comunidad científica. El primero, a partir de instrumentación de laboratorio de propósito general y de plataformas de hardware libre. El segundo, diseñado y construido exclusivamente a partir de plataformas de hardware libre y diseños electrónicos propios. Se destaca que, éste último, presenta una muy alta precisión a pesar de que su coste es muy reducido. Como caso de aplicación, se han implementado en el software de control y tratamiento de datos varios métodos sencillos de extracción de parámetros y se ha analizado su grado de validez a la hora de caracterizar sistemas fotovoltaicos de tercera generación basados en células tándem. También se ha culminado un estudio más extenso del comportamiento de cada uno de estos parámetros en comparación entre tecnologías FV de silicio monocristalino y células tándem.Obtaining the characteristic curve Current - Voltage (I-V) of a photovoltaic device is the essential experiment that provides the most information about its behavior. This PhD thesis aims to provide solutions to the main limitations of current commercial PV characterization systems. As the most outstanding results, two systems have been developed that are open and easily reproducible by the scientific community. The first one, from general purpose laboratory instrumentation and free hardware platforms. The second one, designed and built exclusively from free hardware platforms and electronic designs. This last one has a very high precision in despite of its low cost. As a case of application, several simple methods of parameter extraction have been implemented in the control and data processing software and their level of validity has been analysed when characterising third generation photovoltaic systems based on tandem cells. A more extensive study of the behavior of each of these parameters in comparison between monocrystalline silicon PV technologies and tandem cells has also been performed.Tesis Univ. Jaén. Departamento de: Ingeniería Electrónica y Automática. Leída el 19 de mayo de 2020

Smart grid technology deployment and impact assessment at eThekwini electricity.

M. Sc. Eng. University of KwaZulu-Natal, Durban 2014.The world‟s population is increasing rapidly and is projected to reach 8 billion within the next few decades. Urban migration is also on the rise and it is estimated that there would be significant growth in Africa and more Africans will reside in urban rather than rural areas by 2030. eThekwini, as a leading city in Africa has to establish practices to enable that it utilizes its current resources optimally and sustainably to cater for its future energy and resource requirements. The role of Smart Grid (SG) systems as an electricity industry enabler has been recognized throughout the developed world. The effective introduction and implementation of SGs is also regarded as a major enabler to realize some of the key objectives at local, provincial and national government levels. Significant investment has gone into modernizing the existing electricity grid infrastructure at eThekwini to make it smarter, albeit with varying degrees of success. The term “SG” refers to optimizing, automating and modernizing of the electrical network so that it monitors, protects and automatically optimizes the operation of its interconnected elements. In the eThekwini context, this would include the electricity purchase points from Eskom; distributed generation injection points; the high-, medium- and low voltage networks as well as the industrial, commercial and domestic consumers and their applications and devices. The SG is characterized by a two way flow of electricity and information to create an optimized and automated network that has self-healing properties. It would incorporate the benefits of distributed computing and modern communication systems to deliver information in real-time which enables the almost instantaneous balance of supply and demand. SGs will be designed to ensure high levels of reliability, security, quality, availability and will also aim to improve economic productivity, minimize environmental impact, maximize safety and improve quality of life. The aim, objective and research question of this study will address as to how eThekwini‟s SG maturity levels compare to local and international peers, whether the SG technology deployment is aligned with its objectives, to ascertain the impact of SG implementation and whether the anticipated benefits are being realized. The concept of SG has only been recently formalized at eThekwini and very little research has been conducted in this area which this study aims to address

DOE Solar Energy Technologies Program FY 2006 Annual Report

The DOE Solar Energy Technologies Program FY 2006 Annual Report chronicles the R&D results of the U.S. Department of Energy Solar Energy Technologies Program for Fiscal Year 2005. In particular, the report describes R&D performed by the Program's national laboratories (National Renewable Energy Laboratory, Sandia National Laboratories, Oak Ridge National Laboratory, and Brookhaven National Laboratory) and university and industry partners

Photovoltaic self-consumption heating system: analytical model, experimental results and autonomy prospects

Mención Internacional en el título de doctorIn the European Union, buildings are responsible for 40% of energy consumption and 36% of CO₂ emissions, which contribute significantly to anthropogenic climate change. Since heating represents the major portion of energy consumption in buildings in Spain, renewable heating systems emerge as an alternative to mitigate this problem. This thesis proposes a heating system in which the PV production is self-consumed by a heat pump. For this purpose, a photovoltaic off-grid system that feeds an air-water heat pump to heat a small building through radiant loor has been designed and built. The building, despite the aim of being independent, incudes connection to the grid, so the heat pump supply can be switched between the photovoltaic microgrid and the conventional grid. The photovoltaic array, with a total area of 15.7m² and useful area of 14m², is composed by 12 modules, nominal power of 180W each. Heat pump's nominal heating power is 6kW, which is in fine with building's maximum thermal load. To size properly this type of photovoltaic system, it is necessary to go beyond peak sun hours term commonly used by installers and to simulate realistically photovoltaic production over time. The method known as five-parameter model, details the working curve of a module for a given cell temperature. In this thesis, production has been addressed from a physical point of view, emphasizing the influence of solar cells' temperature on their efficiency. A heat transfer model has been developed, which allows to determine accurately cell temperature under changing meteorological conditions, and then to calculate the photovoltaic production in each moment, basing on technical specifications commonly provided by the modules' manufacturers. This dissertation includes the experimental validation of both cell temperature and photovoltaic production models. The efficiency of the used modules, according to their total area, is 13.73% at 25°C, 12.08% at 50°C and 10.76% at 70°C. The proposed method is easily adaptable to any type of photovoltaic module, once its material composition is known, and its output can be simulated for any tilt angle and location, for where meteorological data are available. Depending on obtained working temperatures, the use of hybrid photovoltaic/thermal modules can be considered. The photovoltaic production model was simulated for the heating period from 4/12/2012 to 30/04/2013, predicting an achievable production of 1265.8kWh and an average cell temperature of 21.3°C, which reaches an average daily maximum value of 47.5°C. The intercepted solar energy during that period was 8869.4kWh, so the efficiency of the array according to its useful area would be 14.3%, instead of the nominal value of 15.4%. The photovoltaic heating system was experimentally tested during the same heating period. The array produced 820.8kWh of electricity. The seasonal photovoltaic efficiency was 9.26%. The achieved production was significantly lower than the achievable one, according to the simulation. The heat pump was fed with 723.9kWh of electricity, 501.4kWh of which carne from photovoltaic source: useful efficiency of the system 5.7%. Several factors caused that efficiency, such as electrical losses in diverse conversions, control system's limitations, storage system's capacity and fit of the production to the demand. The ammount of heat supplied to the radiant floor was 2321.9kWh. The seasonal COP was 3.2 and system's global efficiency was 18.2%. The system was isolated from the grid at 69.3%. Greenhouse gases emissions saved were 170.5kgco₂ comparing to feeding the theat pump with conventional electricity (for an emission factor of 0,34kgco₂ /kWh); 835.9 kgco₂ comparing to supplying the same heat ammount through a gas-oil C boiler; 573.6 kgco₂ comparing to a natural gas boiler. On the other hand, refrigerant leaks were equivalent to 132.1 kgco₂.Actualmente, en la Unión Europea los edificios demandan un 40% del consumo total de energía y son responsables del 36% de emisiones de gases de efecto invernadero, contribuyendo significativamente al calentamiento global antrópogénico. Dado que la calefacción supone la principal porción del consumo energético en los edificios en España, los sistemas de calefacción renovable surgen como una alternativa para mitigar dicha problemática. Esta tesis plantea un sistema de calefacción fotovoltaica en el que la producción eléctrica es auto-consumida por una bomba de calor. Para ello se ha diseñado y construido un sistema fotovoltaico sin inyección a red para alimentar una bomba de calor aire-agua que calienta un pequeño edificio mediante suelo radiante. El edificio, tendente a la autonomía, incluye conexión a red, por lo que el suministro a la bomba de calor puede permutarse entre la micro-red fotovoltaica y la red convencional. El campo fotovoltaico, con un área total de 15,7m² y útil de 14m² , está compuesto de 12 paneles, de 180W de potencia nominal cada uno. La potencia térmica nominal de la bomba de calor es de 6kW, al igual que la carga térmica máxima del edificio. Para dimensionar adecuadamente un sistema fotovoltaico de estas características es necesario simular realísticamente la producción fotovoltaica a lo largo del tiempo. En esta tesis, se ha abordado la producción desde un punto de vista físico, haciendo hincapié en 'la influencia de la temperatura de las celdas solares en su eficiencia. Se ha desarrollado un modelo de transferencia de calor que permite determinar con exactitud la temperatura de celda para condiciones meteorológicas cambiantes y, a partir de ahí, la producción fotovoltaica en cada momento, basándose en especificaciones comunmente suministradas por los fabricantes de módulos. La validación experimental del modelo, tanto para la predicción de la temperatura de celda como para la producción fotovoltaica, es incluida en la presente tesis. La eficiencia de los módulos utilizados, respecto a su área total, es de 13.73% a 25°C, 12.08% a 50°C y 10.76% a 70°C. El método planteado es fácilmente adaptable a cualquier tipo de módulo fotovoltaico a partir de los materiales que lo componen, y su producción simulable para cualquier ángulo de inclinación y localización, para la que se disponga de datos meteorológicos. Dependiendo de las temperaturas de trabajo obtenidas, la utilización de paneles híbridos fotovoltaicos/térmicos puede ser planteada. En concreto, el modelo de producción fotovoltaico fue simulado para el periodo de calefacción entre el 4/12/2012 y el 30/04/2013, prediciendo una producción fotovoltaica alcanzable de 1.265,8kWh y una temperatura media de trabajo de celda de 21,3°C, que alcanza una máxima diaria media de 47,5°C. La energía solar interceptada durante ese periodo fue de 8.869,4kWh, por lo que la eficiencia del campo considerando su área útil sería del 14,3%, frente al 15,4% nominal. El sistema de calefacción fotovoltaica fue estudiado experimentalmente durante el mismo periodo de calefacción. El campo produjo 820,8kWh de electricidad, por lo que la eficiencia fotovoltaica estacional fue del 9,26%. La producción obtenida fue inferior a la potencialmente alcanzable, de acuerdo con la simulación. La bomba de calor fue alimentada con 723,9kWh de electricidad, de los cuales 501,4kWh provenían de la fuente fotovoltaica: eficiencia útil del sistema del 5,7%. Multiples factores provocaron dicha eficiencia, tales como las pérdidas eléctricas en las diferentes conversiones, limitaciones del sistema de control, capacidad del sistema de almacenamiento y ajuste de la producción a la demanda. El calor suministrado al suelo radiante fue 2.321,9kWh. El COP estacional de la bomba de 11 calor fue de 3,2 y el rendimiento global del sistema del 18,2%. El sistema operó autónomo de la red a un 69,3%. Las emisiones de gases de efecto invernadero ahorradas fueron de 170,5kgco₂ respecto a alimentar la bomba de calor con electricidad convencional (para un factor de emisión de 0,34kgco₂ /kWh); de 835,9kgco₂ respecto a suministrar el mismo calor a partir de gas-oil C; de 573,6 kgco₂ respecto al uso de gas natural. Por otra parte, las fugas de refrigerante equivalieron a 132,1 kgco₂.Los resultados científicos que se presentan son fruto de la financiación por parte del Ministerio de Ciencia e Innovación del proyecto Diseño, construcción y evaluación experimental de un sistema de refrigeración solar y trigeneración de alta eficiencia para edificios e invernaderos (ENE2010-20650-C02-01) y de la ayuda FPI (BES-2011-050706). El Ministerio de Economía y Competitividad financió la Estancia Breve (EEBB-I-13-06021) en la Universidad de Wisconsin-Madison.Programa Oficial de Doctorado en Ingeniería Mecánica y de Organización IndustrialPresidente: Francisco Javier Rey Martínez.- Secretario: María Carmen Venegas Bernal.- Vocal: Rafael Antonio Salgado Mangua