Open Access

Im April 2000 wurde das Erneuerbare-Energien-Gesetz (EEG) in Deutschland beschlossen, mit dem ein Rechtsrahmen für die Förderung von regenerativen Stromerzeugungstechnologien geschaffen wurde. Zum 31.12.2020 sind erstmalig ca. 19.000 Anlagen aus dem zwanzigjährigen Förderzeitraum gefallen. Mit jedem Jahreswechsel folgt ein weiterer Jahrgang. Mit der EEG-Novelle 2021 wurden die Voraussetzungen für einen möglichen Weiterbetrieb der ausgeförderten Anlagen geschaffen. In dieser Masterarbeit wird untersucht, welche Optionen betroffene Anlagenbetreiber von Photovoltaikanlagen mit maximal zehn Kilowattpeak haben und aufgezeigt, welche rechtlichen und technischen Vorgaben bestehen. Zu Beginn wird in die Grundlagen der Photovoltaikinstallation und die Regulatorik des EEG eingeführt. Der Anlagenbestand mit Inbetriebnahme im Zeitraum 2000 bis 2008 wird quantifiziert, die Regionalverteilung sowie bisherige Stilllegungen analysiert. Mit einer Systemsimulation wird ein Weiterbetriebsjahr einer Photovoltaikanlage zur Bewertung der Erlöse bei Umstellung auf Überschusseinspeisung mit teilweisem Eigenverbrauch des Solarstroms berechnet. Abschließend werden die Erlöse für die Weiterbetriebsvarianten unter der Preissituation des Jahres 2021 verglichen. Es zeigt sich, dass der Großteil der Photovoltaikanlagen maximal zehn Kilowattpeak aufweist und sich in Bayern und Baden-Württemberg befindet. Die Mehrheit der bereits betroffenen Anlagen wird aktuell weiterbetrieben. Die höchsten finanziellen Überschüsse lassen sich mit der Umstellung auf Eigenverbrauch erzielen. Am einfachsten umzusetzen ist dahingegen der Weiterbetrieb in Volleinspeisung. Die sonstige Direktvermarktung kann eine Alternative zur Volleinspeisung darstellen. Mit einem Neubau ist eine deutliche Leistungssteigerung auf gleicher Dachfläche möglich, ohne einer Weiterbetriebsperspektive verbleibt die Demontage der Anlage.

We present a new concept of 3D polymer-based 1 × 4 beam splitter for wavelength splitting around 1550 nm. The beam splitter consists of IP-Dip polymer as a core and polydimethylsiloxane (PDMS) Sylgard 184 as a cladding. The splitter was designed and simulated with two different photonics tools and the results show high splitting ratio for single-mode and multi-mode operation with low losses. Based on the simulations, a 3D beam splitter was designed and realized using direct laser writing (DLW) process with adaptation to coupling to standard single-mode fiber. With respect to the technological limits, the multi-mode splitter having core of (4 × 4) μm 2 was designed and fabricated together with supporting stable mechanical construction. Splitting properties were investigated by intensity monitoring of splitter outputs using optical microscopy and near-field scanning optical microscopy. In the development phase, the optical performance of fabricated beam splitter was examined by splitting of short visible wavelengths using red light emitting diode. Finally, the splitting of 1550 nm laser light was studied in detail by near-field measurements and compared with the simulated results. The nearly single-mode operation was observed and the shape of propagating mode and mode field diameter was well recognized.

This thesis aims to support the product development process. Therefore, an approach is developed, implemented as a prototype and evaluated, for automated solution space exploration of formally predefined design automation tasks holding the product knowledge of engineers. For this reason, a classification of product development tasks related to the representation of the mathematical model is evaluated based on the parameters defined in this thesis. In a second step, the mathematical model should be solved. A Solver is identified able to handle the given problem class. Due to the context of this work, System Modelling Language (SysML) is chosen for the product knowledge formalisation. In the next step the given SysML model has to be translated into an object-oriented model. This translation is implemented by extracting information of a ".xml"-file using the XML Metadata Interchanging (XMI) standard. The information contained in the file is structured using the Unified Modelling Language (UML) profile for SysML. Afterwards a mathematical model in MiniZinc language is generated. MiniZinc is a mathematical modelling language interpretable by many different Solvers. The generated mathematical model is classified related to the Variable Type and Linearity of the Constraints and Objective of the generated mathematical model. The output is stored in a ".txt"-file. To evaluate the functionality of the prototype, time consumption of the different performed procedures is measured. This data shows that models containing Continuous Variables need a longer time to be classified and optimised. Another observation shows that the transformation into an object-oriented model and the translation of this model into a mathematical representation are dependent on the number of SysML model elements. Using MiniZinc resulted in the restriction that models which use non-linear functions and Boolean Expressions cannot be solved. This is because the implementation of non-linear Solvers at MiniZinc is still in the development phase. An investigation of the optimally of the results, provided by the Solvers, was left for further work.

Purpose: The purpose of this qualitative phenomenological study is to explore the of self-initiated expatriates prior to and during acculturation to life in a smaller periphery region such as Vorarlberg, Austria. By providing insights into their lived experience this research aims to fill in the gaps of missing information on motivators, success factors to adjustment, issues, and stressors, and more that SIEs experience when adjusting. Specifically, what items promote adjustment and what items hinder adjustment. Findings: Developed a better understanding of how and what motivational factors lead to expatriation. Furthermore, that opportunities arise by chance. During acculturation, language factors (dialect), cultural differences act as stressors. While social support, and organizational support, learning of the language act as promoters of acculturation. Further Research could be done including ethnicities, SIEs moving from developed to developing countries, adjustment in regions with dialect vs no dialect. Key words: self-initiated expatriates, expatriation, acculturation, adjustment, promoting acculturation, hindering acculturation.

Traditional power grids are mainly based on centralized power generation and subsequent distribution. The increasing penetration of distributed renewable energy sources and the growing number of electrical loads is creating difficulties in balancing supply and demand and threatens the secure and efficient operation of power grids. At the same time, households hold an increasing amount of flexibility, which can be exploited by demand-side management to decrease customer cost and support grid operation. Compared to the collection of individual flexibilities, aggregation reduces optimization complexity, protects households’ privacy, and lowers the communication effort. In mathematical terms, each flexibility is modeled by a set of power profiles, and the aggregated flexibility is modeled by the Minkowski sum of individual flexibilities. As the exact Minkowski sum calculation is generally computationally prohibitive, various approximations can be found in the literature. The main contribution of this paper is a comparative evaluation of several approximation algorithms in terms of novel quality criteria, computational complexity, and communication effort using realistic data. Furthermore, we investigate the dependence of selected comparison criteria on the time horizon length and on the number of households. Our results indicate that none of the algorithms perform satisfactorily in all categories. Hence, we provide guidelines on the application-dependent algorithm choice. Moreover, we demonstrate a major drawback of some inner approximations, namely that they may lead to situations in which not using the flexibility is impossible, which may be suboptimal in certain situations.