Several models were developed for the analysis of metal-semiconductor solar cells. The models presented are: (i) a limit model to obtain an idea of what the maximum conversion efficiency of metal-semiconductor solar cells is followed by; (ii) a model suitable for the prediction of the performance of metal/single-crystal silicon solar cells; and (iii) a general model for calculating the efficiency of solar cells fabricated from materials other than Si such as GaAs. Extensive use of numerical methods were required to arrive at solutions to the equations presented in the latter two models. The operation of the models is demonstrated using n-and p-type Si and GaAs with Au being taken as the barrier metal. Calculations are presented showing the effect on solar energy conversion efficiency of surface recombination velocity, barrier height, minority-carrier lifetime, barrier metal thickness, collecting grid configuration, and cell thickness. A comparison of practical and computed data for the Au/n-GaAs system yields good agreement. Based on the results of the calculations, it is shown that metal-semiconductor solar cells provide solar energy conversion of medium efficiency and improvements in efficiency depend on the development of high barrier-height systems. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Solar cells have traditionally been used for a direct sunlight to energy conversion, and there has been relatively little investigation into their use as a low data rate optical detector. This report summarizes the results of experimental work to model a silicon solar cell, and its response to a pulse of light. A lumped circuit model, and governing equations for each of the elements is developed. Experimental data on several cells are used to curve fit the governing equations. The parameters of interest are tested as a function of both temperature, and background illumination. Having derived a working model, using open circuit measurements, the behavior of the operational model can be predicted for several values of load resistance. The energy of the output pulse and the Fourier spectrum of the output of the cell are heuristically examined.

No description available.

by Leung Ming-yuen. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1982 / Bibliography: leaves 174-177

by Chow Lap-wai. / Thesis (M.A.)--Chinese University of Hong Kong, 1980. / Bibliography: leaves 185-188.

Thesis (Ph. D.)--Northeastern University, 2008. / Title from title page (viewed June 24, 2009). Graduate School of Engineering, Dept. of Electrical and Computer Engineering. Includes bibliographical references (p. 205-213).

This thesis is a study of the properties of thin GaAs films grown on molybdenum substrates by the close spaced vapour transport (CSVT) deposition technique with the intention that the GaAs/Mo structure would be used as the semiconductor and substrate for economic solar cells. The GaAs films were polycrystalline cubic crystals with no preferred orientation. The crystallite area increased with the temperature at which the substrate was held during growth and at 710°C grain sizes of 100 μm² were observed. The crystallites formed a columnar-like structure with crystal size comparable to the film thickness. No impurities of foreign instrus-ions existed in the films in quantities observable on the electron micro-probe. The resistivity of the GaAs films was 220 Ω cm, hence acceptable for thin film solar cells, however, the GaAs/Mo contact was mildly rectifying. Diodes were fabricated by the deposition of Au onto the GaAs films and the resulting barriers showed values of barrier height of approximately 0.8 eV, ideality factor n = 1.5 to 2, and depletion-layer majority carrier concentration of roughly 10¹⁶ cm⁻³ as measured by J-V and C-V methods. The GaAs films show promise for use in solar cells provided that the Mo/GaAs interface resistance can be reduced. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

One application for photovoltaic (PV) technology is in providing electricity for educational aids, in developing areas remote from grid supply. Technical, social and economic aspects of this option are investigated, in local context, by examining the use of small PV systems to power educational television and video in secondary schools in Bophuthatswana. Technical performance was assessed through monitoring PV system behaviour and climatic variables over an extended period, using remote data-capture techniques at a demonstration site. Modelling provided for further prediction of performance in nonobserved conditions. Social and educational aspects of the schools television project were investigated through interviews with educationists, planners, project administrators and a limited sample of teachers and pupils in Bophuthatswana. Overall conclusions are that PV systems can provide a reliable and technically appropriate solution to the problem of powering light electrical loads in off-grid schools. Levelised unit energy costs can be acceptable if PV systems are critically sized, and if there is close match between designed capacity and actual load energy demand. If this is not the case - as in Bophuthatswana school systems - unit energy costs may be very high. Organisational features of project implementation and inadequate central resources, particularly for delivering appropriate educational software to schools, have impaired the potential of the project, and the equipment in schools is under-utilised. Proceeding from an inductive performance analysis of the monitored system, a PV system performance model was developed, in order to assess the optimum sizing of components in small stand-alone photovoltaic systems in such applications, and to judge the sizing of the systems installed. The model is based upon critical runs of adverse weather, leading to-wards system loss of power to load. It predicts the minimum insolation required to avoid system loss of power to load over runs of days, and compares this with percentiles for plane-of-array insolation over runs of days, derived from long term · hourly weather station records. The approach allows development of a loss of power probability (LOPP) sizing methodology which preserves the run-length characteristics of local climatic data. Sizing predictions from this method are compared with other sizing methodologies, and are used to indicate design savings possible for the monitored systems. The proposed critical-run LOPP sizing method has potential for incorporation in a microcomputer-based sizing tool, suitable for more accurate design of photovoltaic systems with battery storage in local applications.

The optical detector characteristics of a silicon solar cell are examined. A general equivalent circuit model is developed and typical parameter values are determined. A comparison is made between the photovoltaic and short circuit operating modes and the short circuit mode is shown to be preferable in terms of linearity, extended frequency response, and temperature stability. A method is developed to determine the noise characteristics of the amplifier-detector system used in the short circuit mode. The silicon solar cell is shown to be an economical alternative to standard photodiodes in low to medium data rate systems.

published_or_final_version / abstract / toc / Mechanical Engineering / Master / Master of Philosophy