A successful model that could accurately predict the performances of n+-p-p+ concentrator solar cells should include a model of carrier photogeneration rates consistent with the spectral content of the incident light. Furthermore, a finite back surface recombination velocity should be considered since new techniques such as 'Back Surface Field' were developed to reduce the recombination rate at the rear of the cell.In the present work, a two-dimensional concentrator solar cell is modeled for low levels of injection. The model however, assumes an incident light containing one single wavelength. The incident light is assumed to decrease linearly from the center of the illuminated area until it vanishes at the edges of the cell. Finite recombination velocities are taken into account at the front and the back surfaces. Finite-width space charge regions are also included. The transport equations are solved for the carrier concentrations in different regions of the cell. The current density expressions are derived. The generation of theoretical current voltage characteristics is outlined. However, the use of these characteristics to predict cell performances is left for further research. / Department of Physics and Astronomy

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

Solar concentrating systems are often used to decrease the cost of solar energy by redirecting the incident sunlight from a relatively large area onto a photovoltaic cell of smaller area. In addition to the convergence characteristics of the concentrator, indices of refraction and reflectivities which are functions of wavelength can result in an illumination which varies both spatially and spectrally on the solar cell. Nonuniformity can also be induced by concentrator tracking error. The effects of such nonuniform illumination on solar cell performance are of interest.In this investigation, a model of a concentrator solar cell consisting of a network of preexisting one-dimensional models has been developed. This model is analyzed for three sample grid configurations for both spot-focusing and line-focusing concentrator applications.Ada computer programs have been created which, together with a few other pieces of readily available software, are capable of simulating the model. Sample simulations have been performed for line-focusing concentrator applications. These results are presented and discussed. / Department of Physics and Astronomy