Dissertation (PhD)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Solar power systems are becoming increasingly popular due to the fact that solar power can offer time and money saving solutions for off-grid and grid-connected homes, cabins, and businesses with clean and affordable energy. However, there are still significant opportunities to reduce the cost of solar power systems by optimizing system design. This paper presents a methodology for evaluating the lifecycle labor costs of solar power systems. This methodology can help optimize system designs relative to cost. It can also support solar power system selection decisions based on a holistic lifecycle view. The methodology accomplishes this by first presenting a method to evaluate the modularity of competing systems, or design variants. It then describes a method of gathering data and modeling the systems so that it can be communicated to relevant stakeholders. Finally, it uses discrete event simulation to generate an estimate of relative lifecycle labor cost performance. Verification and validation of the methods described are presented through a case study of the MegaModule residential solar power system, designed by the team at GTRI. The paper concludes with a review of limitations and proposed future work.

To optimise the performance of concentrating solar power systems, a detailed knowledge of the resultant flux distribution in the imaging plane is required. To achieve this, an accurate model of the direct solar beam impinging on the concentrator is essential. This thesis presents an empirical model of the terrestrial solar distribution that has both a high-correlation to observed data and an invariance to a change in location. The model is based on the amount of circumsolar radiation in the direct beam and takes into account the small variations that are due to atmospheric scattering. A modelling framework is developed to simulate the flux distribution in the imaging plane of a generic solar concentrating system. Algorithms are developed to include the following: the spatial solar energy distribution; the systemic effect of reflecting that distribution off a non-ideal mirrored surface; the spectral energy distribution; the transmission, absorption and reflection characteristics of optical thin films; and the coordinates of the solar vector. The framework is then used to investigate the performance of anti-reflection coatings on silicon substrates and the performance of linear Fresnel systems. Combined, these algorithms and simulation tools can be applied to create comprehensive optical models of solar concentrating systems.

During the 2005 growing season two irrigation management practices were developed for cabbage production utilizing a Greenfield solar powered miniature pivot, located at the Canada-Saskatchewan Irrigation Diversification Centre (CSIDC) near Outlook, Saskatchewan. Solar and battery power was used to operate the drive and control system of the miniature centre pivot located on CSIDCs pressurized pipeline. The management practices included a low-flow, 94 litres per minute (lpm) schedule with irrigation events occurring in the evening and night periods, and a high-flow, 370 lpm schedule with irrigation events occurring during the daytime hours. In each management practice, the soil moisture content was maintained above 65% of field capacity to optimize yield and head development (Waterer 2005).<p>Over the 2006 growing season, testing was conducted to evaluate the performance of each management practice. Performance was based upon application uniformity, water use efficiency and energy use efficiency. In addition to performance evaluation, tests were conducted to determine operational characteristics of this relatively new irrigation system to identify potential use in agricultural production. <p>The uniformity coefficient of the high-flow management practice was greater than that of the low-flow management practice. This was a result of nozzle selection and layout of each application system, as determined by the manufacturer. <p>Water use efficiency increased significantly when converting from a high-flow operating system to the low-flow system. This increase in water use efficiency was a result of reduced water loss, in the high flow system, through evaporation and potential run-off due to decreased application rates and environmental factors between watering times. Water loss through this manner is not beneficial to plant growth and results in elevated operating costs with little to no improvement in yield. <p>Energy use efficiency, due to differences in water use efficiency and friction loss in the piping system, also increased upon switching from a high-flow system to the low-flow system. In general, converting this type of system from a high-flow management practice to a low-flow management practice will help conserve water and energy resulting in savings in operating and capital costs.<p>Testing to determine the operating characteristics of the power system was completed during the 2006 growing season. It was concluded that these systems have potential use in operating small-scale pivot and pumping systems on high-value crops.

During the 2005 growing season two irrigation management practices were developed for cabbage production utilizing a Greenfield solar powered miniature pivot, located at the Canada-Saskatchewan Irrigation Diversification Centre (CSIDC) near Outlook, Saskatchewan. Solar and battery power was used to operate the drive and control system of the miniature centre pivot located on CSIDCs pressurized pipeline. The management practices included a low-flow, 94 litres per minute (lpm) schedule with irrigation events occurring in the evening and night periods, and a high-flow, 370 lpm schedule with irrigation events occurring during the daytime hours. In each management practice, the soil moisture content was maintained above 65% of field capacity to optimize yield and head development (Waterer 2005).<p>Over the 2006 growing season, testing was conducted to evaluate the performance of each management practice. Performance was based upon application uniformity, water use efficiency and energy use efficiency. In addition to performance evaluation, tests were conducted to determine operational characteristics of this relatively new irrigation system to identify potential use in agricultural production. <p>The uniformity coefficient of the high-flow management practice was greater than that of the low-flow management practice. This was a result of nozzle selection and layout of each application system, as determined by the manufacturer. <p>Water use efficiency increased significantly when converting from a high-flow operating system to the low-flow system. This increase in water use efficiency was a result of reduced water loss, in the high flow system, through evaporation and potential run-off due to decreased application rates and environmental factors between watering times. Water loss through this manner is not beneficial to plant growth and results in elevated operating costs with little to no improvement in yield. <p>Energy use efficiency, due to differences in water use efficiency and friction loss in the piping system, also increased upon switching from a high-flow system to the low-flow system. In general, converting this type of system from a high-flow management practice to a low-flow management practice will help conserve water and energy resulting in savings in operating and capital costs.<p>Testing to determine the operating characteristics of the power system was completed during the 2006 growing season. It was concluded that these systems have potential use in operating small-scale pivot and pumping systems on high-value crops.

No description available.

To optimise the performance of concentrating solar power systems, a detailed knowledge of the resultant flux distribution in the imaging plane is required. To achieve this, an accurate model of the direct solar beam impinging on the concentrator is essential. This thesis presents an empirical model of the terrestrial solar distribution that has both a high-correlation to observed data and an invariance to a change in location. The model is based on the amount of circumsolar radiation in the direct beam and takes into account the small variations that are due to atmospheric scattering. A modelling framework is developed to simulate the flux distribution in the imaging plane of a generic solar concentrating system. Algorithms are developed to include the following: the spatial solar energy distribution; the systemic effect of reflecting that distribution off a non-ideal mirrored surface; the spectral energy distribution; the transmission, absorption and reflection characteristics of optical thin films; and the coordinates of the solar vector. The framework is then used to investigate the performance of anti-reflection coatings on silicon substrates and the performance of linear Fresnel systems. Combined, these algorithms and simulation tools can be applied to create comprehensive optical models of solar concentrating systems.

Thesis (MScIng)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

abstract: Solar power generation is the most promising technology to transfer energy consumption reliance from fossil fuel to renewable sources. Concentrated solar power generation is a method to concentrate the sunlight from a bigger area to a smaller area. The collected sunlight is converted more efficiently through two types of technologies: concentrated solar photovoltaics (CSPV) and concentrated solar thermal power (CSTP) generation. In this thesis, these two technologies were evaluated in terms of system construction, performance characteristics, design considerations, cost benefit analysis and their field experience. The two concentrated solar power generation systems were implemented with similar solar concentrators and solar tracking systems but with different energy collecting and conversion components: the CSPV system uses high efficiency multi-junction solar cell modules, while the CSTP system uses a boiler -turbine-generator setup. The performances are calibrated via the experiments and evaluation analysis. / Dissertation/Thesis / M.S. Electrical Engineering 2013

The success of the South African policy to reduce carbon emissions and incorporate solar energy production into the national energy mix is partly dependent on the ability to persuade householders to become more energy efficient, and to encourage installation of domestic solar systems. Solar power is an innovation in South Africa and the current policy of stimulating the market with subsidies for solar water heaters is not resulting in widespread adoption. The high upfront costs have been a barrier in the past but as more suppliers offer financing options, there has been a gradual increase in purchasing but not at the rate required to save the 578 MW of electricity over the next few years. This research report takes the form of a survey of two consumer groups (“early adopters” and “early majority” adopters in South Africa, with the aim of: • Investigating consumer attitudes towards characteristics of solar systems, • Utilising the diffusion of Innovations theory to understand the attributes which affect the consumer decision making process, and • Isolating the characteristics that are preventing a pragmatic “early majority” from adopting the technology. The results show that overall, while the “early majority” demonstrate a positive perception of the environmental characteristics of solar power, its financial, operational and aesthetic characteristics are limiting adoption. Differences existing between the two groups show support for the concept of the ‘chasm’ between adopter categories identified by Moore. The study concludes that if consumers cannot identify the relative advantage of solar power over their current source of power supplied readily and cheaply through the national grid, it is unlikely that wide-scale adoption will follow. Copyright / Dissertation (MBA)--University of Pretoria, 2012. / Gordon Institute of Business Science (GIBS) / unrestricted