Thesis (M.S.)--Drexel University, 2006. / Includes abstract. Includes bibliographical references (leaves 65-68).

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2017. / The development of solar roads to convert insolation on vast stretches of land to electrical energy, otherwise dedicated solely for transportation, is in its nascent stage. A great potential is seen for PV application with the maturing of solar road technology. Apart from increasing the versatility by smart utilization of land resources, widening the cover of renewable energy generation will lead to a sustainable, secure energy future. A stand-alone solar pathway for public park lighting or area lighting system, completely independent of the power grid, was designed and operated. Public lighting for 65 m stretch of walkway located next to the Electrical, Electronic and Computer Engineering Department building, was chosen as a case study in this study. The case study presented simplified method for sizing, performance evaluation and simulation of a stand-alone solar pathway to power public lighting on the Bellville Campus of the Cape Peninsula University of Technology. Depending on the requirements of the electrical, the quantity and quality of lighting, as well as the required duration of the lighting were calculated. Battery storage capacity, based on the desired autonomy period, and maximum and average daily depth of discharge, were sized. PV array size, based on the type and specifications of PV module, the time of year with the highest average daily lighting load and minimum solar radiation, were selected and measured. Control strategies for battery protection and lighting control conditions were determined, and the control set points were specified. The operating efficiency of solar pathway was evaluated and showed excellent performance compared to the expected with annual average value of the monthly performance ratio and system efficiency. A stand-alone solar pathway system was programmed using MATLAB, in order to size a PV system to the supply public lighting for the walkway. The computer program used, can be applied to any site with different weather conditions.

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

University of Macau / Faculty of Science and Technology / Department of Electromechanical Engineering

M.Eng. / The need and problem was originated from the trends of the earths dwindling energy resource. As time progresses humans are becoming more aware of need to use so called “alternative energy sources” to alleviate the main energy converters i.e. power stations. The student was tasked with investigating the thermal performance of a solar powered refrigeration cycle (prototype) that could: produce enough refrigeration effect that it replaces the standard home vapour compression unit, used for cooling or freezing of foods, heats up a geyser sufficiently to have hot water for a common house hold, has excess energy to heat or cool liquid or air based environments and has the potential to lower the electrical bill of a house. The introductory step was to obtain the thermo fluid properties of aqua ammonia solutions. A setback came about when determining the aqua ammonia properties. There were too many conflicting properties being yielded by six different authors. In an attempt to gain confidence in only one author a comparison table was prepared. The table compared the six authors to each other. By looking at all the values compared it brought great clarity to the problem. When continuing the research into the fundamental law approach of solving for the cycle new findings were made. Initially very little comprehensive studies were done which explained in fundamental laws to solve for the absorption cycle. After extensive reviewing of a detailed study on how to solve for absorption refrigeration cycles, then it was able to begin improving on the thermo – fluid design of the cycle. As cycle and component design began to progress the train of thought began to steer in a direction. Each component needed to be detail designed. The advantage of having each component specifically catered for in the cycle design was that it would increase the cycle efficiency. In this way it would ensure that during the concept generation phase the functioning of each component was clear, thereby enabling a clear understanding of how components would compliment each other in a cycle. A mode of solving for the cycle was to endeavour that all parameters could be calculated unambiguously, with the aid of computerisation. Testing was carried out on a real life commercial thermal siphoning machine in order to realistically understand how absorption refrigeration works and gain experience. At the end of the study the most important result is that the dissertation research shows strong evidence that it will be possible to create a device which can fulfil the four tasks listed above. Another result is a program which is a refined cycle design of the pump absorption type refrigeration. The program solves for points along the cycle. Lastly it was found that even though EES was the simpler program to use for aqua ammonia solution properties it was the only program which catered for sub cooling and super heating.

This thesis studies the optimal design for a photovoltaic-powered medium-head (30 meters) water pumping system, with the emphasis on improving the efficiency and reducing the maintenance requirements of the electrical subsystem. The reduction of maintenance requirements is realized by replacing the conventional brush-type permanent magnet dc motor with a brushless dc (BLDC) motor. Different BLDC motor control techniques such as position-sensorless operation, sinusoidal and trapezoidal excitations are investigated. The improvement in efficiency is achieved by maximizing the output power from the photovoltaic array and by minimizing the losses in various parts of the electrical sub-system. A microprocessor-based double-loop maximum power tracking scheme is developed for maximization of the photovoltaic array output power. Over 99% utilization factor is achieved for a typical clear day regardless of the season of the year. The system losses are minimized mainly by performing loss analysis and selecting most suitable switching topologies and switching components. Experimental results show that the combined converter-motor efficiency is comparable to those of high-efficiency brush-type dc motor systems. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

In this study, the techno-economic feasibility of converting an existing process steam plant into a combined heat and power plant, using an external solar thermal field as the additional heat source was studied. Technical feasibility entailed designing a suitable heat exchanger, which uses hot oil from the solar field to raise the steam conditions from dry saturated to superheated. The solar field was sized to heat a selected heat transfer fluid to its maximum attainable temperature. A suitable turbine-alternator was chosen which can meet the required plant power demand. For this to be a success, the processes which require process steam were analysed and a MathCAD model was created to design the heat exchanger and check turbine output using the equations adapted from various thermodynamics and power plant engineering texts, together with the Standards for the Tubular Exchanger Manufacturer's Association. The U.S. National Renewable Energy Laboratory system advisor model was used to size the suitable solar field. A financial model was developed in Excel to check the economic feasibility of the project, using discounted payback period as the economic indicator. It was found out that amongst loan interest rates, variation of system output and the electricity output, the profitability of the project was largely influenced by the electricity tariff. An optimum size for the heat exchanger of 30ft was established from the sensitivity analysis and it was concluded that the project is currently not economically viable on an independent investor financing model, unless either the electricity tariff improves or the solar thermal energy and turbine technology costs decrease.

The amount of traditional energy sources are finite and the ecological impact of continuing to produce energy using fossil fuels will only exacerbate the carbon footprint. It is for these reasons that photovoltaic modules are becoming a larger and more necessary part the world's electricity production paradigm. Photovoltaic (PV) semiconductor modules are grouped into three categories. 'First generation' monocrystalline and polycrystalline silicon modules that consist of pn junctions created via the addition of impurities known as dopants. Almost 85% of solar cells produced at this time are `first generation' and it is the high production costs of silicon PV modules that motivated the search for new methods and materials to use as PV cells. 'Second generation' PV modules consist of semiconductor thin films. The 'second generation' PV modules in production at this time are copper indium gallium diselenide (CIGS), copper indium gallium (CIG), amorphous silicon (a-Si), and cadmium telluride (CdTe). The 'third generation' PV modules consist of dye-sensitized and organic materials. Thin films use less material, have less stringent production parameters and less waste, making thin films cost effective. In this investigation, solar cells were prepared using un-doped Group II-VI semiconductor thin films that exploit differences in bandoffsets to form effective p-n heterojunctions as a viable low cost alternative to doping. The thin films were deposited by thermal evaporation upon glass substrates coated with indium tin oxide (ITO). A layer of aluminum formed the back contact. Various configurations of the solar cells were produced including: ITO/CdS/CdSe/Al, ITO/ZnTe/CdSe/Al, ITO/CdTe/CdSe/Al, ITO/ZnTe/CdTe/CdS/Al. The solar cells produced have been characterized to determine thin film internal resistances, quantum and 'wall-plug' efficiencies, as well as I-V and spectral response. The open circuit voltage, short circuit current density, fill factor, and efficiency of our best devices were 0.26 V, 4.6 mA, 27.5 and 0.4% respectively. Additional device optimization should be possible and should improve these results. Solar cell design based on band-offset is an effective method for predetermining likely PV structures, while future investigation using Group II-VI semiconductor nanowires and nanorods and employing epitaxial films are likely to enhance the efficiency.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for degree of Master of Science in Chemistry / The mandate for renewable energy sources to replace the current reliance on fossil fuels as a primary energy source has recently attracted a lot of research interest. The research has also focussed on bringing the technologies that take into consideration the goal of reducing environmental pollution. Consequently, approaches using photovoltaic (PV) technologies have been a promising arena to tackle the problem facing energy sources. Recently, more focus has been placed on improving the power conversion efficiency (PCE) of PV devices, such as organic and/or organic-inorganic hybrid perovskite solar cells. Therefore, in this work two different materials were applied in two independent PV devices, namely organic and/or organic-inorganic hybrid perovskite solar cells. One study employed nitrogen doped broken hollow carbon spheres (N-bHCSs), with an aim of enhancing the electronic properties of the P3HT:PCBM active layer of an organic photovoltaic (OPV) solar cell. N-bHCSs were successfully synthesized using a horizontal chemical vapour deposition method (H-CVD) employing a template-based method and the carbon was doped using in-situ and ex-situ doping techniques. Pyridine, acetonitrile and toluene were used as both carbon and nitrogen precursors. The dispersity of the SiO2 spheres (i.e. templates) was found to play a role on the breakage of the N-bHCSs. Incorporation of the N-bHCSs into the P3HT:PCBM active layer was found to enhance the charge transfer and this led to less recombination of photogenerated charges in the interface between the donor and acceptor. The current-voltage (I-V) characteristics of the ITO/PEPOT:PSS/P3HT:PCBM:N-bHCSs/Al solar cell devices revealed an increased chargetransport distance due to increased electron density by n-type doping from the N-bHCSs. The second study employed the organic-inorganic hybrid perovskite (CH3NH3PbI3) material as a light harvesting layer in an ITO/PEDOT:PSS/CH3NH3PbI3/PC6BM/Al solar cell device. Initially, the device parameters were optimised to obtain the best performing device. These include parameters such as the degradation of the hybrid film as a function of time and air exposure. A rapid degradation was seen on the device after 24 h of air exposure which was accompanied by the decrease in the PV performance of the device. The degradation was visually seen by the formation of crystal grains (i.e. “islands”) on the perovskite film. / GR2019