Solar Electricity from Concentrator Photovoltaic Systems

This thesis examines the prediction of concentrator photovoltaic system performance, and a model is presented where estimates are made using basic, fundamental material and atmospheric parameters, and successfully validated against measurements from a deployed system, to within 2% accuracy. A method to characterise the impact of individual atmospheric parameters on concentrator photovoltaic system performance is detailed and results are presented for potential deployment locations around the globe, demonstrating substantial differences in energy yield prediction accuracy if insufficient information is available, with up to 75% relative difference in energy yield and levelised cost of energy between basic and detailed simulations. In addition, the competitiveness of concentrator photovoltaic systems in different locations are benchmarked against existing technologies, showing significant geographical variation in their financial viability. The material quality in single and multijunction solar cells and its effect on the selection of optimal solar cell designs is investigated and the radiative efficiency of a device is proposed as a figure of merit to evaluate material quality. The optimal band gaps are shown to vary substantially depending on material quality at low solar concentrations, by hundred of milli-electron-volts, with ramifications for future solar cell designs. The impact of photon management, through radiative coupling, on cell performance is quantified for current and future high efficiency multijunction solar cell structures. Up to 5% enhancement due to radiative coupling can be expected for quad-junction solar cells, but current designs can expect below 1% enhancement. The work covered in this thesis has investigated and highlighted the potential problems associated with not fully understanding the atmospheric conditions in which concentrator photovoltaic systems operate, providing evidence and impetus for additional ground measurements or a drastic improvement in satellite-based measurement of atmospheric conditions. By integrating atmospheric parameters into an existing concentrator photovoltaic system modelling tool, new methods to characterise these conditions has been developed rigorously and accurately simulate system behaviour, a valuable resource to the field. In the design of optimal band gaps for multijunction solar cells, the work in this thesis shows that the material quality must be carefully considered in any design. A novel method has been developed to quantify material quality and provide a benchmark of state-of-the-art achieved values. The role of photon management in the form of radiative coupling is quantified, through the first examination of enhancement due to the effect, under realistic atmospheric conditions. This gives cell designers realistic expectations for performance enhancement.Open Acces