Matching Items (12)
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- All Subjects: solar
- Creators: Electrical Engineering Program
- Member of: Theses and Dissertations
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
Description
In this thesis, a novel silica nanosphere (SNS) lithography technique has been developed to offer a fast, cost-effective, and large area applicable nano-lithography approach. The SNS can be easily deposited with a simple spin-coating process after introducing a N,N-dimethyl-formamide (DMF) solvent which can produce a highly close packed SNS monolayer over large silicon (Si) surface area, since DMF offers greatly improved wetting, capillary and convective forces in addition to slow solvent evaporation rate. Since the period and dimension of the surface pattern can be conveniently changed and controlled by introducing a desired size of SNS, and additional SNS size reduction with dry etching process, using SNS for lithography provides a highly effective nano-lithography approach for periodically arrayed nano-/micro-scale surface patterns with a desired dimension and period. Various Si nanostructures (i.e., nanopillar, nanotip, inverted pyramid, nanohole) are successfully fabricated with the SNS nano-lithography technique by using different etching technique like anisotropic alkaline solution (i.e., KOH) etching, reactive-ion etching (RIE), and metal-assisted chemical etching (MaCE).
In this research, computational optical modeling is also introduced to design the Si nanostructure, specifically nanopillars (NPs) with a desired period and dimension. The optical properties of Si NP are calculated with two different optical modeling techniques, which are the rigorous coupled wave analysis (RCWA) and finite-difference time-domain (FDTD) methods. By using these two different optical modeling techniques, the optical properties of Si NPs with different periods and dimensions have been investigated to design ideal Si NP which can be potentially used for thin c-Si solar cell applications. From the results of the computational and experimental work, it was observed that low aspect ratio Si NPs fabricated in a periodic hexagonal array can provide highly enhanced light absorption for the target spectral range (600 ~ 1100nm), which is attributed to (1) the effective confinement of resonant scattering within the Si NP and (2) increased high order diffraction of transmitted light providing an extended absorption length. From the research, therefore, it is successfully demonstrated that the nano-fabrication process with SNS lithography can offer enhanced lithographical accuracy to fabricate desired Si nanostructures which can realize enhanced light absorption for thin Si solar cell.
In this research, computational optical modeling is also introduced to design the Si nanostructure, specifically nanopillars (NPs) with a desired period and dimension. The optical properties of Si NP are calculated with two different optical modeling techniques, which are the rigorous coupled wave analysis (RCWA) and finite-difference time-domain (FDTD) methods. By using these two different optical modeling techniques, the optical properties of Si NPs with different periods and dimensions have been investigated to design ideal Si NP which can be potentially used for thin c-Si solar cell applications. From the results of the computational and experimental work, it was observed that low aspect ratio Si NPs fabricated in a periodic hexagonal array can provide highly enhanced light absorption for the target spectral range (600 ~ 1100nm), which is attributed to (1) the effective confinement of resonant scattering within the Si NP and (2) increased high order diffraction of transmitted light providing an extended absorption length. From the research, therefore, it is successfully demonstrated that the nano-fabrication process with SNS lithography can offer enhanced lithographical accuracy to fabricate desired Si nanostructures which can realize enhanced light absorption for thin Si solar cell.
ContributorsChoi, JeaYoung (Author) / Honsberg, Christiana (Thesis advisor) / Alford, Terry (Thesis advisor) / Goodnick, Stephen (Committee member) / Arizona State University (Publisher)
Created2015
Description
A primary motivation of research in photovoltaic technology is to obtain higher efficiency photovoltaic devices at reduced cost of production so that solar electricity can be cost competitive. The majority of photovoltaic technologies are based on p-n junction, with efficiency potential being much lower than the thermodynamic limits of individual technologies and thereby providing substantial scope for further improvements in efficiency. The thesis explores photovoltaic devices using new physical processes that rely on thin layers and are capable of attaining the thermodynamic limit of photovoltaic technology. Silicon heterostructure is one of the candidate technologies in which thin films induce a minority carrier collecting junction in silicon and the devices can achieve efficiency close to the thermodynamic limits of silicon technology. The thesis proposes and experimentally establishes a new theory explaining the operation of silicon heterostructure solar cells. The theory will assist in identifying the optimum properties of thin film materials for silicon heterostructure and help in design and characterization of the devices, along with aiding in developing new devices based on this technology. The efficiency potential of silicon heterostructure is constrained by the thermodynamic limit (31%) of single junction solar cell and is considerably lower than the limit of photovoltaic conversion (~ 80 %). A further improvement in photovoltaic conversion efficiency is possible by implementing a multiple quasi-fermi level system (MQFL). A MQFL allows the absorption of sub band gap photons with current being extracted at a higher band-gap, thereby allowing to overcome the efficiency limit of single junction devices. A MQFL can be realized either by thin epitaxial layers of alternating higher and lower band gap material with nearly lattice matched (quantum well) or highly lattice mismatched (quantum dot) structure. The thesis identifies the material combination for quantum well structure and calculates the absorption coefficient of a MQFl based on quantum well. GaAsSb (barrier)/InAs(dot) was identified as a candidate material for MQFL using quantum dot. The thesis explains the growth mechanism of GaAsSb and the optimization of GaAsSb and GaAs heterointerface.
ContributorsGhosha, Kuṇāla (Author) / Bowden, Stuart (Thesis advisor) / Honsberg, Christiana (Thesis advisor) / Vasileska, Dragica (Committee member) / Goodnick, Stephen (Committee member) / Arizona State University (Publisher)
Created2011
Description
The Phoenix CubeSat is a 3U Earth imaging CubeSat which will take infrared (IR) photos of cities in the United Stated to study the Urban Heat Island Effect, (UHI) from low earth orbit (LEO). It has many different components that need to be powered during the life of its mission. The only power source during the mission will be its solar panels. It is difficult to calculate power generation from solar panels by hand because of the different orientations the satellite will be positioned in during orbit; therefore, simulation will be used to produce power generation data. Knowing how much power is generated is integral to balancing the power budget, confirming whether there is enough power for all the components, and knowing whether there will be enough power in the batteries during eclipse. This data will be used to create an optimal design for the Phoenix CubeSat to accomplish its mission.
ContributorsBarakat, Raymond John (Author) / White, Daniel (Thesis director) / Kitchen, Jennifer (Committee member) / Electrical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
A hybrid PV/T module was built, consisting of a thermal liquid heating system and a photovoltaic module system that combine in a hybrid format. This report will discuss the work on the project from Fall 2012 to Spring 2013 and the extended section on the economics for the Honors Thesis. Three stages of experiments were completed. Stage 1 showed our project was functional as we were able to verify our panel produced electricity and increased the temperature of water flowing in the system by 0.65°C. Stage 2 testing included “gluing” the flow system to the back of the panel resulting in an average increase of 4.76°C in the temperature of the water in the system. Stage 3 testing included adding insulating foam to the module which resulted in increasing the average temperature of the water in our flow system by 6.95°C. The economic calculations show the expected energy cost savings for Arizona residents.
ContributorsHaines, Brent Robert (Author) / Roedel, Ronald (Thesis director) / Aberle, James (Committee member) / Rauch, Dawson (Committee member) / Barrett, The Honors College (Contributor) / Electrical Engineering Program (Contributor)
Created2013-05
Description
A hybrid PV/T module was built, consisting of a thermal liquid heating system and a photovoltaic module system that combine in a hybrid format. This report will discuss the work on the project from Fall 2012 to Spring 2013. Three stages of experiments were completed. Stage 1 showed our project was functional as we were able to verify our panel produced electricity and increased the temperature of water flowing in the system by 0.65°C. Stage 2 testing included “gluing” the flow system to the back of the panel resulting in an average increase of 4.76°C in the temperature of the water in the system. Stage 3 testing included adding insulating foam to the module which resulted in increasing the average temperature of the water in our flow system by 6.95°C.
ContributorsDenke, Steven Michael (Author) / Roedel, Ron (Thesis director) / Aberle, James (Committee member) / Rauch, Dawson (Committee member) / Barrett, The Honors College (Contributor) / Electrical Engineering Program (Contributor)
Created2013-05
Description
Growing up in Ghana West Africa, I realized there were a few major obstacles hindering the education of the youth. One of them was the consistent supply of all year-round power. Therefore, pursuing a career in power electronics, I decided to research and implement a budget-friendly DC-AC converter that can take power from a DC source such as a solar panel to make AC power, suitable for grid-implementation. This project was undertaken with two other colleagues (Ian Vogt and Brett Fennelly), as our Senior Design Capstone project. My colleagues primarily researched into the "advanced" part of the converter such as Volt-VAR, Maximum Power Point Tracking (MPPT), and variable power factor, making the Capstone project be dubbed as "Smart Inverter". In this paper, I elaborate on the entire process of my research and simulation, through the design and layout of the PCB board to milling, soldering and testing. That was my contribution to the capstone project. After testing the board, it was concluded that although the inverter was intended to be the very inexpensive, some electrical and design principles could not be compromised. The converter did successfully invert DC power to AC, but it was only at low voltage levels; it could not withstand the higher voltages. This roadblock stymied the testing of advanced functionalities, paving way for an avenue of further research and implementation.
ContributorsAsigbekye, John (Author) / Ayyanar, Raja (Thesis director) / Sedillo, James (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
The project described here is a solar powered intrusion detection system consisting of three modules: a battery recharging circuit, a laser emitter and photodetector pair, and a Wi- Fi connectivity board. Over the preceding seven months, great care has been taken for the design and construction of this system. The first three months were spent researching and selecting suitable IC's and external components (e.g. solar panel, batteries, etc.). Then, the next couple of months were spent ordering specific materials and equipment for the construction of our prototype. Finally, the last two months were used to build a working prototype, with a substantial amount of time used for perfecting our system's packaging and operation. This report will consist of a detailed discussion of our team's research, design activities, prototype implementation, final budget, and final schedule. Technical discussion of the concepts behind our design will assist with understanding the design activities and prototype implementation sections that will follow. Due to the generous funding of the group from the Barrett Honors College, our overall budget available for the project was $1600. Of that amount, only $334.51 was spent on the actual system components, with $829.42 being spent on the equipment and materials needed for the testing and construction of the prototype. As far as the schedule goes, we are essentially done with the project. The only tasks left to finish are a successful defense of the project at the oral presentation on Friday, 29 March 2013, followed by a successful demo on 26 April 2013.
ContributorsTroyer, Nicole L. (Co-author) / Shtayer, Idan (Co-author) / Guise, Chris (Co-author) / Kozicki, Michael (Thesis director) / Roedel, Ronald (Committee member) / Goodnick, Stephen (Committee member) / Barrett, The Honors College (Contributor) / Electrical Engineering Program (Contributor)
Created2013-05
Description
Wire connected solar cells are a promising new technology that can increase the efficiency and reduce the cost of solar modules. The use of wire rather than ribbon bus bars can lead to reduced shading, better light trapping, and reduced material costs, all while eliminating the need for soldering. This research first analyzes the optimal wire gauge to reduce cracking and improve efficiency. Wire sizes between 20 AWG and 28 AWG were tested, with the optimal size being between 24 AWG and 26 AWG for the ethylene vinyl acetate (EVA) layer used in the module. A polyethylene sheet was then added between the wires and EVA layer to prevent the EVA from running underneath the wires during lamination, ultimately allowing for a more uniform contact and only a slight reduction in quantum efficiency. Then, a comparison between tinned copper wires and indium coated copper wires is shown. A mini-module efficiency of 20.0% has been achieved using tinned copper wires, while indium coated copper wires have produced a mini-module efficiency of 21.2%. Thus, tinned copper wires can be a viable alternative to indium coated copper wires, depending on the needs of the customers and the current price of indium. The module design throughout the research utilizes a planar assembly method, which improves the ease of manufacturing for wire interconnection technology. A two-cell base component is constructed and shown, with the intended future application of making large wire connected modules. Finally, wire applications in both single-cell and four-cell flexible modules are explored, with an efficiency of 18.65% achieved on a single-cell, flexible, heterojunction solar module using wire interconnections. A fully flexible four-cell string is developed, and future recommendations for related research are included.
ContributorsTyler, Kevin Daniel (Author) / Bowden, Stuart (Thesis director) / Herasimenka, Stanislau (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12
Description
The honors thesis presented in this document describes an extension to an electrical engineering capstone project whose scope is to develop the receiver electronics for an RF interrogator. The RF interrogator functions by detecting the change in resonant frequency of (i.e, frequency of maximum backscatter from) a target resulting from an environmental input. The general idea of this honors project was to design three frequency selective surfaces that would act as surrogate backscattering or reflecting targets that each contains a distinct frequency response. Using 3-D electromagnetic simulation software, three surrogate targets exhibiting bandpass frequency responses at distinct frequencies were designed and presented in this thesis.
ContributorsSisk, Ryan Derek (Author) / Aberle, James (Thesis director) / Chakraborty, Partha (Committee member) / Electrical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
Energy poverty is the lack of access to the basic energy resources needed for human development. Fossil fuels, through their heavy emissions and transience, are slowly but surely leaving room for change in the energy sector as renewable energy sources rise to the challenge of sustainable, clean, and cost-efficient energy production. Because it is mostly located in rural areas, solutions crafted against energy poverty need to be appropriate for those areas and their development objectives. As top contenders, photovoltaics insertion in the energy market has largely soared creating, therefore, a need for its distributed energy resources to interconnect appropriately to the area electrical power system. EEE Senior Design Team 11 saw in this the need to design an advanced photovoltaic inverter with those desired grid functions but also leveraging the technological superiority of wide bandgap devices over silicon semiconductors. The honors creative project is an integral part of the senior design capstone project for Team 11. It has a two-front approach, first exploring the IEEE 1547-2018 standard on distributed energy resources; then focusing on the author’s personal contribution to the aforementioned senior design project: digital signal processing and grid support implementation. This report serves as an accompanying write up to the creative project.
ContributorsTall, Ndeye Maty (Author) / Ayyanar, Raja (Thesis director) / Kozicki, Michael (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05