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Title: Characterisation of solar concentrating systems for photovoltaics and their impact on performance
Author: Paul, Damasen Ikwaba
ISNI:       0000 0004 2718 3513
Awarding Body: University of Ulster
Current Institution: Ulster University
Date of Award: 2011
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The use of concentrating systems has a great potential to become the lowest-cost PV option if the high energy flux in the concentrated PV module can be utilised efficiently. In this study, a PV module with isolated cells was designed and fabricated with the purpose of examining the performance of each cell under concentrated (using CPC and V-trough) and non-concentrated light. Before the experimental characterisation, a detailed optical analysis for the CPC and V-trough collectors was undertaken. It was found that in spite of both concentrators having the same concentration ratio and aperture area, the angular acceptance and optical efficiency for the CPC were always higher than those of the V-trough for incidence angles above ± 20° and ± 10° , respectively. A comparison of flux distribution on the absorber of the two concentrators indicated that the energy flux was more uniform in the V -trough collector than in the CPC collector. The experimental energy flux concentration for the CPC collector (at normal incidence angle) varied from 0.9 to 3.6, with higher irradiance concentrated near the edges of the PV module. As a result, the CPC performed better with cells located near the edges of the PV module than those at the centre. On the other hand, the energy concentration for the V -trough collector varied from 1.3 to 2.5, with higher irradiance concentrated at the centre of the PV module. The use of the CPC and V-trough concentrators increased the power output of a PV module by 25% and 46%, respectively, compared to a similar non-concentrated PV module. The fabricated isolated cells PV module was used to evaluate, theoretically and experimentally, the energy flux distribution on the surface of a concentrated PV module under CPC and V -trough concentrators. From the analysis, it was found that in both collectors, the experimental optical efficiency (indoor and outdoor) results follow the theoretical ones with reasonable accuracy, especially the outdoor experimental results. The comparison between outdoor and indoor experimental optical efficiencies in each collector showed that there was good agreement between the two results, both for low and high incidence angles. The effects of non-uniform illumination on the performance of a single standard PV cell, at low and medium energy flux concentration ratios as well as the effect of orientation, size and geometrical shapes of non-uniform illumination were studied. It was found that the effect of non-uniform illumination on various cell performance parameters becomes noticeable at medium energy flux concentration ratio. The results also indicated that the performance of a single conventional PV cell depends neither on the location and size of the non-uniform illumination nor the geometrical shape of the non-uniform illumination. A novel hybrid PV cell consisting of low and high efficiency PV cells was designed and fabricated. The electrical energy produced by the hybrid cell was compared, theoretically and experimentally, with a similar low efficiency single PV (LESPV) cell in a low- concentrating symmetric CPC suitable for facade, sloping roof, flat roof and rear side building integration. Both results, simulation and experimental, showed that the daily electrical energy produced by a hybrid cell for different Belfast (UK) sky conditions was higher than that of the LESPV cell, but not to the expected value.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available