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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Framtidens elnät : Hur elbilar och solceller påverkar på det lokala elnätet / Future Electricity Networks : How Electrical Car and Solar Panels Impact on the Distribution Electricity Networks

Laphai, Zaw San, Polat, Sedat January 2015 (has links)
The purpose of the project is to determine the impact of solar cells and electrical vehicles on the future electricity grid and distribution network. Future electricity grids will be affected differently than it does today. Therefore, it is important to determine the impacts so that the current electricity distribution system can be developed and redesign to achieve the future demand. In Sweden, government has changed rules and laws in order to make it easier for private sector to invest in renewable energy sources. Our project focused on the impact of the solar cells and electric vehicles on the low voltage electricity distribution. Solar cells have become more popular than ever and that leads to many countries in utilizing their energy needs from solar and the same is going to happen here in Sweden. It is needed to find out how the impacts on the low voltage grids will be if many private individual install solar panels in their own homes and what will happen when they start to supply electricity, which is excess from the production of their solar cells, back to the grid? What should be done in order to maintain the electricity’s quality in term of voltage? Meanwhile, electric vehicle popularity rises every year, which means that electricity demand will rise proportionally with the number of electric cars in the country. Should something be done with the power supply to meet the power needs of electric cars? Is it possible to use the electrical car battery as a backup power? How electric vehicle charging’s behavior will impact on the low voltage? In this project, data and pictures has taken from different sources and consolidated for analysis purpose. This thesis contained information about solar radiation, solar cells, electric vehicles, and batteries, rules for installation of solar cells regulations, electricity grids, and electrical power quality, results of researching and eventual solutions for expected problems. / <p>Presentation har gjort med båda svenska och norska språket . </p>
2

Optimering av solcellsdriven gatubelysning / Optimization of solar-powered street lighting

Imamovic, Enver, Gitmis, Koral January 2022 (has links)
Detta examensarbete riktar sig in på att undersöka olika typer av solceller, batterier och lampor för att ta fram och jämföra två system av solcellsdriven gatubelysning i Stockholm och Kiruna. Sverige befinner sig väldigt norr ut på jordklotet vilket innebär en stor kontrast i soltimmar under sommar- och vinterhalvåret. Arbetets huvudsyfte är att ta fram ett solcellsdrivet system där energi genererad under sommaren kan lagras i ett batteri och sedan kompensera för energiunderskottet under vintern. Resultaten visar att skillnaden av genererad energi är stor beroende på vilken solcell som används. Beroende på val av solceller skiljer sig även kravet på batterikapaciteten för respektive ort. Energiupptaget från solceller i Stockholm och Kiruna skiljer sig markant, detta beror på olikheten av globalstrålningen.  Resultaten från kostnadsberäkningen visar att belysningssystemen som studeras i arbetet är dyrare i Kiruna än i Stockholm, detta beror på skillnaden i krav på batterikapacitet utifrån genererad energi från solcellerna. Val av batteri- och solcellstyp har även en påverkan på kostnaden. / This thesis focuses on examining different types of solar cells, batteries, and lamps to develop and compare two systems of solar-powered street lighting in Stockholm and Kiruna. Sweden is located very north of the globe, which means a great contrast in sunny hours during the summer and winter months. The main purpose of the study is to develop a solar-powered system where energy generated during the summer can be stored in a battery and then compensate for the energy deficit during the winter. The results show that the difference in generated energy is large depending on which solar cell is used. Depending on the choice of solar cells, the requirement for battery capacity for each location also differs. The energy uptake from solar cells in Stockholm and Kiruna differs significantly, this is due to the difference in global radiation. The results from the cost calculations show that the lighting systems studied in the thesis are more expensive in Kiruna than in Stockholm, this is due to the difference in requirements for battery capacity based on the energy generated from the solar cells. The choice of battery and solar cell type also has an impact on the cost.
3

Off grid eller energiplushus. : Är det möjligt att gå off grid?

Dahlbom, Roland January 2020 (has links)
Målet med den här undersökningen har varit att se om fastigheten Orkestern 1 går att koppla off-grid och om det är ekonomiskt försvarbart eller om en on-grid lösning är bättre. Förutsättningarna är goda med ett stort tak med plats för solpaneler i öst-västlig riktning och en årsmedelvind på 4 m/s. Då huset är nybyggt och välisolerat är även energiförbrukning låg. För att kunna beräkna hur mycket energi som ska produceras i form av värme och el med hjälp av solceller, vindkraftverk, pelletskamin och dieselverk upprättas en energibalans och energifördelning med hjälp av transmission och ventilationsberäkningar. Lagring av energi görs i form av pellets, batteri och biodiesel. Simuleringsprogrammet för solceller Polysun används för att beräkna produktion av solel över varje månad på året. Diagram upprättas över året indelat i månader där det framgår hur stort energibehovet är och visar hur stor del varje energiproducent har varje månad. En pay-off kalkyl görs för att se om det är ekonomiskt lönsamt och för att kunna jämföra mellan två olika off-grid system. Pay-off kalkylen används också för att jämföra mellan off-grid och on-grid system. Resultatet landar i att on-grid systemet är ekonomiskt hållbart medan off-grid systemet inte är det men är ändå fullt genomförbart. / The main target of this examination has been to see if the real estate Orkestern 1 has the possibility to go off-grid and if it is economical defendable or if on-grid solution is a better way to go. The prerequisites are good with a large roof to place solar panels to the east and west, a yearly average windspeed at 4 m/s and a low energy consumption because the house is new built and well insulated. To calculate how much energy that must be produced in form of heat and electricity with solar cells, windmills, pellet stove and diesel generator an energy balance and an energy distribution will be prepared with help of calculations of transmission and ventilation loses. Storage of energy will be done in form of pellets, battery and biodiesel. The simulation program for solar panels Polysun is used to calculate the produced solar energy for each month on the year. Diagram is prepared for each month to see the need of energy and how much every energy producer is delivering. A straight pay-off calculation is done to see if there are any economic benefits and to compare between off-grid and on-grid systems. The result will be that on-grid system is better economical but still the off-grid system is doable.
4

Materials Engineering and Control for Advancing High-Efficiency CdSe/CdTe Solar Cells

Jamarkattel, Manoj K. 15 June 2023 (has links)
No description available.
5

Diffusion Modeling in Stressed Chalcogenide Thin-Films

Schäfer, Stefan Jerome 06 April 2022 (has links)
Die Effizienz von Verbindungshalbleitern hängt von ihrer lokalen Zusammensetzung und ihrer räumlichen Elementverteilung ab. Um die opto-elektronischen Eigenschaften solcher Bauelemente zu optimieren, ist ein detailliertes Verständnis und die Kontrolle der Zusammensetzungsgradienten entscheidend. Industriell wichtige Bauelemente sind Absorberschichten für Dünnschichtsolarzellen, die eine hohe Effizienz in Kombination mit einem geringen Materialbedarf und einer hohen elastischen Flexibilität bieten. Ein gängiges Herstellungsverfahren für Dünnschicht-Solarzellenabsorber ist das Annealen bei hohen Temperaturen. Im Gegensatz zu dem, was bei Fick'schen Diffusionsprozessen zu erwarten wäre – führt dieses regelmäßig zur Bildung steiler und stabiler Zusammensetzungsgradienten, die oft von den optimalen Profilen für hocheffiziente Absorber abweichen. In dieser Arbeit liegt das Hauptaugenmerk auf den mechanischen Spannungen, die sich im Inneren von Dünnschichten entwickeln, und auf deren Auswirkungen auf Diffusionsprozesse und die mikrostrukturelle Entwicklung des Materials. Es wird gezeigt, dass die Bildung von elastischen Spannungen die endgültigen Elementverteilungen stark beeinflusst und sogar zur Bildung von starken und stabilen Zusammensetzungsgradienten führt. In dieser Arbeit wird weiterhin argumentiert, dass die Wirkung der Spannungen auf die Gleichgewichts-Zusammensetzungsprofile von den mikrostrukturellen Eigenschaften des Materials abhängen kann, insbesondere vom Vorhandensein von Leerstellenquellen. Ein Vergleich numerischer Berechnungen mit Echtzeitdaten der energiedispersiven Röntgenbeugung, die während der Dünnschichtsynthese in-situ erfasst wurden, hilft zu zeigen, dass die so entwickelten Interdiffusionsmodelle die experimentell beobachteten Beugungsspektren und insbesondere die Stagnation der Interdiffusion vor Erreichen der vollständigen Durchmischung teilweise reproduzieren können. / The operational efficiency of compound semiconductors regularly depends on their local elemental composition and on the spatial distribution of contained elements. To optimize the opto-electronic properties of such devices, a detailed understanding and control of compositional gradients is crucial. Industrially important devices are thin-film solar cell absorber layers which deliver high photo-conversion efficiencies in combination with a low demand of material and high elastic flexibility. These materials use local variations in composition to tune their opto-electronic properties. A common fabrication process for thin-film solar cell absorbers involves annealing at high temperatures to achieve specific compositional gradients, which – contrary to what could be expected from simple Fickian diffusion processes – regularly results in the formation of steep and stable compositional gradients, often deviating from the optimal profiles for high-efficiency absorbers. In this work attention is focused especially on mechanical stresses developing inside thin-films and on their effects on diffusion processes and on the material’s micro-structural evolution. It is shown that the formation of elastic stresses strongly influences the final elemental distributions, even leading to the formation of strong and stable final compositional gradients. However, this thesis also argues that their exact effect on equilibrium composition profiles may depend on the detailed micro-structural properties of the material, especially on the presence of vacancy sources and sinks. A comparison of numerical calculations with real-time synchroton-based energy-dispersive X-ray diffraction data acquired in-situ during thin-film synthesis helps to demonstrate that the such developed interdiffusion models can partly reproduce the experimentally observed diffraction spectra and, especially, the stagnation of interdiffusion before total intermixing is achieved.

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