The thesis deals with detailed theoretical and experimental investigation of noise and transport characteristics of selected photovoltaic cells in both forward and reversed directions focusing on the area of local PN junction instability (within the microplasma regions). It will be studied the correlation among different characteristics.

For increase productivity, the current technology of welding pipes bellows was replaced by laser welding. Experiment was carried out on the material of austenitic stainless steel 1.4541 for sheet thickness 0.25 mm and 0.15 mm. On sheet 0.25 mm was achieved comparable mechanical properties as the current manufacturing process upon achieving 10 times higher welding speeds. Samples of 0.15 mm thickness achieved to about 30% lower deepening over existing technology. For improvement was advised to reduce heat input. From an economic assessment shows that the price per 1 m of weld decreases with increasing speed welding. With higher welding speeds reduces the heat input.

This thesis is focused on the area of analysis and diagnostic of monocrystalline solar cells, using local light radiation. Main goals of this thesis are focused on explanation of generation and behavior microplasma in solar cell, in dependence of temperature and reversed bias voltage. As a next focus of this thesis is strong regions of microplasma sources, analyzed by scanning electron microscope and a detailed analysis of edge and surface structure is made. The influence of the environment (air pressure, level of vacuum and nitrogen gas) on the microplasma generation and behavior is observed in the vacuum chamber of electron microscope. The results from microplasma method are correlated with noise diagnostic method and on the base of these results are set a new thesis and mathematical equations for the defects behavior in different conditions. The outcomes of the research are shared with the manufacturer od silicon solar cells, Solartec s.r.o. company. It is the advanced diagnostic methods that allow improving the quality of the production process, through early detection of individual groups of defects.

The thesis deals with the design of the measurement installation, which is intended for the microplasma noise measurements. This noise is being generated in the defective parts of the PN junction. The goal of this work is to design the measurement installation and to realize the fully functional workbench for the analogical noise related measurements and to determine the transfer function of the measurement installation. Main part of the work is to choose proper parameters for the measuring devices and to design the software intended for the automated measurements. Consequently, we have to process the measured waveforms of the microplasma noise, to determine the dependency of the noise on the signal magnitude and to calculate the power spectral noise density. Finally, we have to determine the transfer function of the measurement installation and to design the inversion filter.

KELČA Daniel: Welding of thin-walled pipe The project, elaborated during the engineering study, field of study M-VTM (Production technology and industrial management) deals with welding of thin-walled pipes Cats in practise. There are methods of WIG and microplasma welding compared. The suggested basic material is corrosion-resistant ferritic steel X2CrMoTi18-2 (1.4521; AISI 444). Welding runs continuously and depends on the demanded length of the thin-walled pipe. The tests of the weld were designed on the basis of a literary study. They should help us together with the economic evaluation to assess the two methods.

The aim of this diploma thesis is an innovation of photoluminescence measure research workplace for measurement of cells structure defects by method of transmissive illumination while employing the current methods of measurement of defect in the solar cells structure. The first part deals with explanation of historical development of solar energy, of how we can reach production of electric power with contribution of solar radiation and defines usability of solar cells in practice. The thesis further analyses a practical application of measurement via laboratory diagnostic methods used by Department of Electrotechnology Brno University of Technology. The second part is focused on mechanical design of experimental photoluminescence measure workspace used for quick diagnostic defects employing the rear arousing source for detection of defects with assistance of transmissive system of illumination. Finally, with co-operation of SOLARTEC s.r.o. three types of solar cells are measured by this new method and compared with results of measurement via diagnostic methods of LBIV (Light Beam Induced Current), LBIC (Light Beam Induced Voltage), Electroluminescence, Photoluminescence, and detection defects by radiation of Microplasma.