Thin-film solar cells on glass substrates are likely to have a bright future due to the potentially low costs and the short energy payback times. Polycrystalline silicon (poly-Si, grain size &gt 1 pm) has the advantage of being non-toxic, abundant, and long-term stable. Glass as a substrate, however, limits the processing temperatures to ~600??C for longer process steps. Films with large grain size can be achieved by solid phase crystallisation (SPC), and especially by solid phase epitaxy (SPE) on seed layers, using amorphous silicon deposited at low temperatures as a precursor film. With SPC and SPE, the amorphous silicon film is typically crystallised at ~600??C over hours. During this anneal at atmospheric pressure -depending on the properties of the amorphous silicon film- ambient gas can percolate the film and can negatively affect the crystallisation. In this work, a high-vacuum anneal chamber was designed and built to allow the in-situ crystallisation of amorphous silicon films deposited on glass in a PECVD cluster tool. An important aspect of the design was the comfortable and safe operation of the vacuum anneal chamber to enable unattended operation. This was realised by means of a state-of-the-art, programmable temperature controller and a control circuit design that incorporates various safety interlocks. The chamber interior was optimised such that a temperature uniformity of 2-3K across the sample area was achieved. The chamber was calibrated and tested, and SPC and SPE samples were successfully crystallised. In initial SPC crystallisation experiments with solar cell structures, after post-deposition treatments, a 1 -sun open-circuit voltage of 465 mV was obtained, similar to furnace-annealed samples. In initial experiments with SPE solar cell structures, difficulties regarding the characterisation of the unmetallised solar cells with the quasi-steady-state open-circuit voltage method (QSSVOC) were encountered after post-deposition hydrogen treatment. A possible explanation for these difficulties is the contact formation with the metal probes. Furthermore, limiting factors of the QSSVOC method for the characterisation of unmetallised cells with high contact resistance values were investigated and, additionally, the accuracyof the QSSVOC setup was improved in the low light intensity range.

With increasing concerns of global warming and the impending exhaustion of fossil fuels attention is being turned to renewable sources of energy. The sun supplies 3 x 1024 J per year to the earth which is around 104 times more energy than what the human race consumes. The world’s energy needs would be satisfied if a mere 0.1% of the planet’s surface was covered with solar cells(< = 10%)1, causing the conversion of solar energy (sunlight) into electricity to represent a very practical renewable source. Past research into solar energy has produced a photovoltaic device, which when coupled with highly coloured coordination compounds, enables this conversion. This device is known as a dye-sensitised solar cell (DSSC). Further research has been conducted into the properties of the dyes, and has shown that highly coloured coordination compounds are able to convert solar energy into electrical energy with the highest efficiencies. The dominant compounds in this area to date have been Grätzel’s ruthenium complexes and porphyrins. However, there exists a class of smaller compounds called dipyrrins, described most simply as “half a porphyrin”, which possess many of the attractive qualities for DSSC dyes. Although there are no examples of ruthenium-dipyrrin complexes in the literature, the combination of advantageous properties from both components represent very attractive synthetic targets with huge potential as dyes for DSSCs. The objectives of this thesis were firstly to develop a series of dipyrrin complexes which would be suitable as dyes for DSSCs; then to fully characterise the complexes and investigate the spectroscopic properties of each complex; and finally to determine the suitability of the complexes as dyes for DSSCs. These objectives were fully met, resulting in a set of generic target compounds characterised via 1H NMR, 13C NMR, mass spectrometry (ESI-MS), elemental analysis, and x-ray crystallography. From analyses of the UV-visible, fluorescence, emission, and Raman spectra; and electrochemistry results; the complexes were concluded to be suitable as dyes for DSSC’s. An additional bonus is that the syntheses for these complexes are applicable to any dipyrrin, thus aiding future studies into the use of dipyrrins as dyes for DSSC’s. This thesis summarises the findings of the above outlined research project.

Thesis (Ph.D.)--Murdoch University, 2004. / Thesis submitted to the Division of Science and Engineering. Bibliography: 211-229.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 159-168).

Thesis (Ph.D.)--University of Delaware, 2008. / Principal faculty advisors: Valeria Gabriela Stoleru, Dept. of Materials Science & Engineering; and S. Ismat Shah, Dept. of Materials Science. Includes bibliographical references.

Thesis (Ph. D.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 177-194).

Dissertation (Ph.D.)--University of Toledo, 2009. / Typescript. "Submitted as partial fulfillment of the requirements for the Doctor of Philosophy in Physics." Bibliography: leaves 132-148.

Thesis (M.S.)--Florida State University, 2006. / Advisor: Peter Kalu, Florida State University, College of Engineering, Dept. of Mechanical Engineering. Title and description from dissertation home page (viewed Sept. 22, 2006). Document formatted into pages; contains x, 77 pages. Includes bibliographical references.

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Σκοπός της συγκεκριμένης διπλωματικής εργασίας είναι να εξεταστεί η ποιότητα ισχύος ενός μονοφασικού φωτοβολταϊκού συστήματος συνδεδεμένου στο δίκτυο. Αρχικά αναλύονται οι βασικές μονάδες από τις οποίες αποτελείται το φωτοβολταϊκό σύστημα και στη συνέχεια ακολουθεί ο σχεδιασμός και η εξομοίωσή του χρησιμοποιώντας το λογισμικό MATLAB/Simulink. Στο πρώτο κεφάλαιο γίνεται μια εισαγωγή σχετικά με τις ανανεώσιμες πηγές ενέργειας, την ανάγκη χρησιμοποίησης τους και τα πλεονεκτήματα που παρουσιάζουν τα φωτοβολταϊκά συστήματα, σε σχέση με τις υπόλοιπες πηγές που υπάρχουν διαθέσιμες σήμερα. Στο δεύτερο κεφάλαιο παρουσιάζεται η ηλιακή ακτινοβολία. Δίνονται στοιχεία για τον ήλιο και το ηλιακό δυναμικό της χώρας μας, ενώ στη συνέχεια εξηγούνται κάποια χαρακτηριστικά μεγέθη της ηλιακής ακτινοβολίας. Στο τρίτο κεφάλαιο αναλύεται η φωτοβολταϊκή γεννήτρια. Παρουσιάζεται αρχικά το φωτοβολταϊκό φαινόμενο, ενώ στη συνέχεια γίνεται μια αναλυτική περιγραφή των ηλιακών κυττάρων, καθώς και της ομαδοποίησης αυτών που οδηγεί στη δημιουργία των φωτοβολταϊκών πλαισίων και κατ’ επέκταση της φωτοβολταϊκής συστοιχίας. Στο τέταρτο κεφάλαιο παρουσιάζονται οι αντιστροφείς, οι οποίοι συνδέουν τη φωτοβολταϊκή γεννήτρια με το δίκτυο. Αναλύεται ο τρόπος λειτουργίας τους και τα λειτουργικά χαρακτηριστικά τους, δίνοντας ιδιαίτερη βαρύτητα στην ημιτονοειδή διαμόρφωση πλάτους παλμών που χρησιμοποιήθηκε στα πλαίσια αυτής της διπλωματικής. Στο πέμπτο κεφάλαιο γίνεται η μελέτη και ο σχεδιασμός του φωτοβολταϊκού συστήματος. Καθορίζονται τα μεγέθη και τα χαρακτηριστικά των κυριότερων στοιχείων από τα οποία αποτελείται, ενώ γίνεται αναφορά και στις απαιτήσεις, όσον αφορά την ποιότητα ισχύος, για την σύνδεση με το δίκτυο ηλεκτρικής ενέργειας. Στο έκτο κεφάλαιο παρουσιάζεται όλη η διαδικασία εξομοίωσης του φωτοβολταϊκού συστήματος, χρησιμοποιώντας το λογισμικό MATLAB/Simulink. Αφού γίνει μία εισαγωγή στο λογισμικό, αναλύεται ο τρόπος δημιουργίας κάθε μέρους από το οποίο αποτελείται το φωτοβολταϊκό σύστημα, δημιουργώντας με αυτόν τον τρόπο το τελικό ολοκληρωμένο μοντέλο εξομοίωσης. Στο έβδομο κεφάλαιο γίνεται η εξομοίωση και παρουσιάζονται τα αποτελέσματά της. Σε κάθε στάδιο της εξομοίωσης γίνεται μεταβολή κάποιων σημαντικών παραμέτρων του συστήματος, όπως η προσπίπτουσα ηλιακή ακτινοβολία, ο DC πυκνωτής, το φίλτρο εξόδου, το φορτίο και το μήκος της γραμμή διανομής, ενώ παρουσιάζονται και τα αποτελέσματα των μεταβολών αυτών, όσον αφορά την ποιότητα ισχύος. Στο όγδοο κεφάλαιο παρουσιάζονται κάποια συμπεράσματα και παρατηρήσεις, με βάση τα αποτελέσματα της εξομοίωσης. / The purpose of this thesis is to examine the power quality of single-phase grid-connected photovoltaic system. At first, the basic units of which it is consisted are analysed and then, the whole photovoltaic system is designed and simulated using the software MATLAB/Simulink. The first chapter contains an introduction to renewable energy sources, the reason why they are necessary and the advantages of the photovoltaic systems, in comparison to the other renewable energy sources that are available nowadays. The second chapter deals with solar energy. It is referred to the sun and the high solar potential of Greece, while some typical parameters of solar radiation are explained. The third chapter contains an analysis of a photovoltaic generator. The photovoltaic effect is described, while there is also a detailed description of solar cells and how they are grouped in order to form the photovoltaic panel. The fourth chapter focuses on the inverters, which connect the photovoltaic generator to the grid. It includes an analysis of the way they work and their functional parameters, giving more importance to the sine-wave pulse width modulation (PWM), which was mainly implemented on this thesis. The fifth chapter constitutes the study and design of the photovoltaic system. The values and the parameters of the main parts of which it consists are determined. In addition, the necessary requirements of power quality that should be met, in order to establish a grid connection, are mentioned. The sixth chapter describes the simulation procedure of the photovoltaic system, using the software MATLAB/Simulink. It contains an introduction to the software and an analytical description of the way each part of the photovoltaic system was created, in order to form the complete simulation model. The seventh chapter contains the simulation and its results. The simulation includes various stages, on which critical parameters of the photovoltaic system, such as the solar radiation, the DC capacitor, the output filter, the load and the length of distribution line are changed, in order to see how these changes affect the power quality. The eighth chapter includes some comments and conclusions, regarding the results of the simulation.