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To model solar cells accurately one must solve coupled second order, partial, linear differential equations derived from Boltzmann's equation, continuity equations and electrostatics. Analytical solutions prove to be insufficient for modeling complex applications such as concentrating systems. A network model and computer programs which use a sophisticated one-dimensional solar cell model were developed to simulate nonuniformly illuminated cells in concentrating systems.This project's task was to make these programs more efficient and to simulate nonuniform illumination cases with higher intensity levels and with spectral variations previously untried. To this end, modifications were effected resulting in a factor of one hundred reduction in the error of gvalue, an important model parameter, a reduction in running time by a factor of ten for the best cases and no less than two for the worst, and an overall simplification of the modeling process.Presented herein are the results of the simulations performed by the model. Eleven cases of nonuniformity previously untested were modeled at different levels of metalization and degrees of nonuniformity. A comparison of the results obtained was also made to previous work done in this field. In addition to the results of the simulations, the actual computer programs of the network model are included. / Department of Physics and Astronomy

High efficiency tandem selective solar absorber materials of carbon in nickel oxide (C-NiO) composite were fabricated on an aluminium substrate using a simple and cost effective sol-gel process. The process involved preparation of carbon and nickel oxide precursor sols which were homogeneously mixed to form a final C-NiO precursor sol. The carbon precursor sol was prepared by dissolving sucrose (SUC) in 8 ml of distilled water. The NiO precursor sol was prepared by dissolving 7.5 g nickel acetate in 50 ml ethanol, then adding 6.3 g diethanol amine (DEA) to stabilise the solution followed by addition of a structure directing template of polyethylene glycol (PEG). The final C-NiO precursor sol was spin coated on pre-cleaned aluminium substrate to form thin films which were then heat treated in nitrogen ambient inside a tube furnace. The final heat treatment temperature of the sols was determined by thermal studies using thermo gravimetric analytic (TGA) and differential scanning calorimetric (DSC) techniques. TGA and DSC studies of the final precursor sol showed that the weight loss of the precursors stabilised at around 450 °C. The impact of the sol-gel process parameters namely heat treatment temperature, PEG content, SUC content as well as spin coating speed on the optical properties i.e. solar absorptance (αsol) and thermal emittance (εtherm) was investigated. It was found that the optical properties as well as photo-thermal conversion efficiency, η = αsol - εtherm, improved with an increase in heat treatment temperature in the range studied (300-550 °C). This is in good agreement with the results obtained from thermo-gravimetric analysis which showed the weight loss of the precursor to stabilise around a temperature of 450 °C. Results obtained from the Raman studies showed a progressive increase in the graphitic domain in C-NiO samples with an increase in temperature. Heat treatment temperatures above 450 °C gave the best optical properties. Scanning electron microscopy (SEM) results showed that samples that did not have PEG in the precursor sol were compact and an addition of PEG in the precursor sol caused an increase in the size and density of pores in the films produced which affected the optical properties. As a result, the optical properties increased with an increase in PEG content from 0 g to 2 g then decreased with further increase in PEG content. It was found that addition of SUC of up to 8 g in the sol did not change the optical properties of the fabricated materials because SUC contributed little carbon to the final composite material. Further increase in SUC content resulted in materials with poor photo-thermal conversion efficiency. An increase in spin coating speed did not change the absorptance of the materials but it improved their thermal emittance. The best spin coating speed was found to be 7000 RPM. A solar absorptance of 0.81 and thermal emittance of 0.06 have been achieved for an optimum sample in this study yielding a photo-thermal conversion efficiency of 0.75. The optimum sample fabricated in this study showed superior optical properties compared to the widely used commercial solar absorber paint. This suggests that the C-NiO composite material has the potential for possible use as a selective solar absorber in a solar collector. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2012.

名古屋大学年代測定総合研究センターシンポジウム報告

This thesis investigates variations in solar irradiance incident upon sloping surfaces under deciduous forest in winter. A model is presented for prediction of solar irradiance at the surface which accounts for slope inclination and orientation, surrounding topography, isotropic absorption of solar radiation by the crown space, and shadows cast by the stem space. / Field data from two sites of different slope and aspect attest to the validity of the model; errors, based on 20-minute averages of instantaneous values, are 15.5% (RMSE) and $-$1.9% (MBE). Error is partially due to reliance upon global radiation measurements above canopy at a different site (partially cloudy conditions) and sampling error (sunny sky conditions). The variability of solar irradiance at the surface, and in the error of predicted values, is found to vary with sky condition, solar zenith and incidence angles, and slope orientation. However, integration to hourly and/or daily time periods improves model performance significantly.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references. / Microfiche. / xii, 158 leaves, bound ill. 29 cm

Typescript. / Bibliography: leaves [144]-149. / xi, 149 l illus

Thesis (M.S. - Agricultural Engineering)--University of Arizona, 1988. / Includes bibliographical references (leaves 81-83).

Thesis (Ph.D.)--Australian National University, 2004.