Abstract This thesis presents measuring techniques as well as measured and simulated results with the aim of helping the design of photovoltaic energy harvesting systems. Therefore, cost-effective measurement setups were developed for collecting the amount of irradiation, for both stationary and moving photovoltaic (PV) installations. The impact of the time resolution of solar radiation data on estimating the available solar energy was investigated. For moving PV installations, the dynamics and the rate of changes in the available irradiation were studied in order to analyse the effects on maximum power point tracking (MPPT) algorithms. In addition, possibilities for harvesting PV energy in indoor environments were also investigated. The main contribution of this thesis is the effective testing of PV cells and complete PV panels: instead of measuring the characteristic I-V (Current-Voltage) response under strictly controlled artificial illumination, photovoltaics are simply biased externally. Then, with the help of synchronized thermography (ST), infrared (IR) images of the PV panel self-heating are recorded. In the obtained IR-images, defected areas are seen as cold spots, since they are not biased by the external power supply. From the calculated temperature variations, the size of the defect area can be calculated and, thus, the loss in output power can be estimated. The method is shown to work both with and without glass encapsulation. / Tiivistelmä Tämä työ esittelee mittaustekniikoita ja mitattuja ja simuloituja tuloksia aurinkoenergian keruujärjestelmien suunnittelun avuksi. Työtä varten kehitettiin kustannustehokas mittausjärjestelmä, jonka avulla arvioitiin aurinkoenergian määrää sekä stationaarisen että liikkuvan valokennon tapauksissa. Näiden lisäksi tutkittiin mittaustaajuuden vaikutusta arvioitaessa saatavilla olevan aurinkoenergian määrää. Liikkuvan PV (photovoltaic)-asennuksen avulla tutkittiin saatavilla olevan aurinkoenergian vaihtelun suuruutta ja nopeutta tarkoituksena analysoida näiden vaikutuksia käytettäviin MPPT-algoritmeihin. Tämä lisäksi tutkittiin myös valoenergian keruumahdollisuuksia sisätiloissa. Työn tärkein kontribuutio on valokennojen ja kokonaisten valopaneelien toiminnallisuuden testaamisen tehostaminen. Tyypillisesti PV:n toiminnallisuus varmistetaan tarkasti määritetyssä ympäristössä suoritetun I-V -ominaiskäyrämittauksen avulla. Tämän työn menetelmä on yksinkertaisesti biasoida PV:t ulkoisesti, minkä jälkeen ST (synchronized thermpgraphy) -kuvauksen avulla määritetään PV-paneelien itselämpenemistä kuvaavat infrapunakuvat. Paneelin vioittuneet alueet erottuvat IR-kuvissa kylminä alueina ulkoisen biasoinnin puuttuessa. IR-kuvista havaituista lämpötilavaihteluista on mahdollista määrittää vioittuneen alueen koko ja siten arvioida myös menetettyä lähtötehoa. Kyseisen metodin toimivuus osoitettiin niin lasikoteloiduilla kuin ilman sitä olevilla PV-paneeleilla.

Le présent travail s'articule autour de l'élaboration du matériau binaire In2S3 en couches minces en tant qu'alternative crédible au composé CdS, dans les cellules solaires à base de CuInS2. Nous avons utilisé la technique de dépôt chimique en solution (Chemical Bath Deposition ou CBD) qui est une technique non coûteuse, non toxique et facile à manipuler. Les couches fabriquées sont caractérisées de différents points de vue et à différentes échelles : caractérisations structurale par diffraction de rayons X (DRX), morphologique par Microscopie Electronique à Balayage (MEB), composition chimique par spectroscopie en dispersion d'énergie (EDS), propriétés optiques par spectrophotométrie, et électriques par la méthode du courant thermiquement stimulé (TSC) et par cartographie de courant localisé. L'objectif de ce travail est l'étude systématique des effets du dopage à l'aluminium et à l'étain, et du traitement thermique des films minces de In2S3 déposés sur verre et sur SnO2. Nous avons réalisé tout d'abord par CBD une multicouche d'In2S3 :4%Al formée par trois dépôts successifs sur des substrats verre et SnO2:F. La comparaison des caractéristiques physicochimiques est faite avec la couche non dopée en tant que caractéristiques de référence. L'étude par DRX faite pour différentes concentrations en Al, montre que ce binaire cristallise selon la structure cubique d'orientation préférentielle (400). Une meilleure cristallisation est obtenue pour une concentration en aluminium dans la solution y = [Al]/[In] = 4%. L'analyse optique montre que le gap est direct, il varie de 2,3 à 2,9 eV; la plus large bande optique est obtenue pour y = 4%. C'est une bonne valeur pour l'utilisation du composé β-In2-xAlxS3 comme fenêtre optique dans les dispositifs photovoltaïques. L'étude de l'effet du dopage à l'étain des multicouches d'In2S3, nous a permis de déduire qu'une meilleure cristallinité, une faible rugosité de la morphologie de surface et un gap optique plus proche de l'optimum théorique, sont obtenus pour des films croissants sur le substrat Pyrex avec une concentration d'étain égale à 2‰. L'analyse effectuée par MEB sur la tranche a montré que l'épaisseur moyenne des couches diminue avec l'augmentation de la concentration d'étain. La présence de l'étain, même en très petites quantités induit des changements importants dans le processus de croissance du film. L'étude TSC montre que l'augmentation de la concentration de l'étain au-delà 2 ‰ conduit à une diminution de courant thermiquement stimulé. Le recuit à différentes températures sous azote est appliqué aux couches dopées et non dopées étudiées précédemment. Le traitement thermique sous azote à 400°C provoque une augmentation nette de la taille des cristallites pour pratiquement tous les films minces dopés ou non dopés déposés sur verre ou sur SnO2. L'analyse par diffraction des rayons X a révélé une conversion de la phase cubique (400) à la phase tétragonale (109) pour l'In2S3:4%. Le changement de la forme des cristallites observé par AFM, met également en évidence l'existence d'une autre phase. Les analyses électriques par TSC montrent particulièrement le comportement électrique de type semiconducteur pour les films minces dopés à 4% Al, et recuit à 400°C, ainsi que pour les films minces dopés à l'étain après recuit à 200°C. L'analyse locale du courant de conduction dans la couche de In2S3 fait apparaître des inhomogénéités plus grandes après traitement thermique. Cependant les bons résultats macroscopiques permettent d'envisager sereinement la fabrication de cellules solaires incluant ces couches. / The present work focuses on the development of binary material In2S3 thin films as an alternative to CdS in thin film solar cells based on CuInS2. We used the technique of Chemical Bath Deposition (CBD) as it is non-expensive, non-toxic and easy to handle. Layers produced are characterized at different levels and scales: cristalline structure by X-ray diffraction (XRD), surface morphology by Scanning Electron Microscopy (SEM), chemical composition by energy dispersive spectroscopy (EDS), optical properties by spectrophotometry and electrical conduction by thermally stimulated currents (TSC) and local mapping of currents. The objective of this work is the systematic study of the effects of aluminum or tin doping, and heat treatment of In2S3 thin films deposited on glass and SnO2. We achieved first a multilayer of CBD In2S3:Al(4%) formed by three successive deposits on glass and SnO2 substrates. Comparison of physicochemical characteristics is made with the undoped layer as reference features. The XRD study done for different Al concentrations, shows that In2S3:Al crystallizes in the cubic structure with preferential orientation (400). Better crystallization is obtained for a concentration of aluminum in the solution y = [Al] / [In] = 4%. The analysis shows that the optical gap is direct, it varies from 2.3 to 2.9 eV, the largest optical band is obtained for y = 4%. It is a good value for the use of the compound β-In2-xAlxS3 as optical window in photovoltaic devices. The effect of tin doping in In2S3 multilayers induces a better crystallinity, low roughness of the surface morphology and optical gap closer to the theoretical optimum, obtained for films grown on Pyrex substrate with a tin concentration equal to 2 ‰. Analysis by SEM on the wafer cleaved-edge showed that the average thickness of the layers decreases with increasing the concentration of tin. The presence of tin, even in very small quantities induced significant changes in the growth process of the film. The TSC study shows that increasing concentration of tin beyond 2‰ leads to a reduction of thermally stimulated current.Annealing at different temperatures under nitrogen is applied to doped and undoped layers studied previously. Heat treatment under nitrogen at 400 ° C causes a net increase of crystallite size for virtually all thin films doped or undoped deposited on glass or SnO2. The analysis by XRD showed a conversion of the cubic phase (400) to the tetragonal phase (109) for In2S3:Al(4%). Change the shape of the crystallites observed by AFM, also highlights the existence of another phase. The TSC analyzes show particular electrical behavior close to semiconductor type for the thin films doped with 4% Al and annealed at 400°C, as well as thin films doped with tin after annealing at 200°C. The local analysis of the conduction current in the layer of In2S3 shows inhomogeneities larger after heat treatment. However, good macroscopic results should allow to fabricate promising solar cells incorporating these layers.

This master thesis analyses the existing methods both practically and theoretically used to detect defected surface area in solar cells. Various methods were used but by using an upgraded CMOS camera without IR filter to implement the electroluminescence method, this has proven to have a very crucial impact on the results. Given the overall results and the acquired information, a procedure with a simple parameter can be setup to carry out the measurements. In addition to this a catalog was formed showing the defects occurring in mono and polycrystalline solar cells.

Basic knowledge of photovoltaic energy transformation, devices and materials, used in photovoltaic are summarized in this master's thesis. The main goal of this thesis is orientation in the photovoltaic systems used these days and explain advantages and disadvantages of these systems during the design phase.

This thesis studies the degradation of perovskite photovoltaic cells placed in atmospheres of different moisture. Samples with inverse structure: ITO/ PEDOT:PSS/ CH3NH3PbI3–XClX / PC70BM/ Ca/ Al were prepared. Electrical characteristics were measured for 2 months and similar degradation trend was observed for all the samples. Perovskite cell efficiency PCE decreased to 20 % of the initial value in t80= 46±3 days in laboratory, t80=23±1$ days in nitrogen atmosphere and t80=25,7±0,6 dní days in dry atmosphere. For the initial 27 days of the experiment, a faster degradation linked with the decrease of ISC, FF and VOC was observed. After this period, the value of FF has stabilised at 0,777±0,009 % and the value of VOC at 0,70±0,02 % of their original value (in the laboratory atmosphere). Additional fall of PCE resulted only from the decrease of ISC and was slower than in the initial period. From the results acquired, it has emerged that during the experiment, the cell encapsulation provided a sufficient barrier against outer moisture. Residual moisture present in the sctructure, was labeled as the source of the degradation. The moisture is believed to enter with the hygroscopic material PEDOT:PSS during the samples preparation procedure. During the degradation, absorption measurements of photovoltaic cells were executed. The absorption spectra didn't change. That indicates, that the decrease of ISC is not caused by the reduction of light absorption. The thesis also studied the degradation of perovskite solar cells under illumination. The samples were exposed to UV radiation for 55,5 hours. The PCE time of decrease to 20 % of the initial value was t80 = 6±2 days. It was revealed, that UV radiation significantly accelerates the decrease of ISC.

This thesis deals with the possibilities of energy transmission by optical fiber for the purpose of powering of electronic systems. It comprises issues of electrical energy conversion to optical energy, coupling the power into the optical fiber, coupling between fiber and opto-electric transducer, conversion of optical energy to electrical energy, and transformation on required voltage levels. The principles of such Power-Over-Fiber are discussed in the first part of the work. Various technologies for the implementation of key system parts and their effectivity are discussed. In the next part, several Power-Over-Fiber commercial devices are compared. Subsequently, systems for Power-Over-Fiber experimental implementations are proposed. They are based on the utilization of semiconductor laser, multimode fiber, photovoltaic cell and related electronic circuits. The final part of the thesis deals with the construction of experimental systems and measurement of parameters of transmitted power and efficiency.

The project considers realization system, which allows us to test six different operation modes on lifetime of accumulators. The system will be connected to computer, that will perform measurement of current and voltage and switch betwen charge and discharge modes. The measured values will be recorded in certain time intervals to computer memory. After some time these measured data will be analised and the most optimal operational mode will be set.

The objective of this thesis is to perform practical measurements of two small photovoltaic power plants, compare the received results with a theoretical calculation, and evaluate how the two differ from each other. Measured data are divided into three groups. The first group evaluates an overall electric power production in the individual months and compares it with the theoretical presumption that is instrumental to a return of investment calculation. The second group shows us a development of electric power production during characteristic days. We can compare how an ideal day from the FVE production point of view looks like, in other words a sunny and clear-sky day, with the opposite case when it is cloudy and raining all day long. Another extreme is a rapid growth or a performance drop, which can happen in a pho-tovoltaic power plant and a time period when this situation can arise. The third group contains statistic data from the electric power production. They are processed in the form of histograms and polygons of production that graphically illustrate production decomposition into the individual months. These data can be instrumental to a decision making about the form of purchase, whether it is economical for us to use the so called green bonus or not.

The project considers realization system, which will allow us to test six different operation modes on lifetime accumulators. The system will link to computer, which will execute measurement current and tension and switch betwencharging and discharging modes. The measured values will record in someone time intervals in to computer memory. After someone time will analise these measured valuer and will provide optional operation mode.

The theoretical part is to outline the possibilities of solar energy conversion, learn about the issues solar cells and describe the history of photovoltaics and photovoltaic energy conversion. Then describe principle of the measurement VA characteristics of photovoltaic cells. This issue is not as easy as it seems at first sight, because the solar cell isn’t a linear component, which is very easy to measure. Analysis of VA characteristic of photovoltaic cells affects parameters such as: light intensity, temperature, serial and parallel resistance, the slope of the light source, and more. The practical part deals with creating a workplace for automatic measurement of VA characteristics of photovoltaic cells in the LabVIEW. Challenge is to create a functional program, which automatically measures the VA characteristics not only in the lighted cells, but also in the shaded cell (diode mode). The program calculates the power and important parameters, such as short-circuit current, open circuit voltage, maximum power, current and voltage at maximum power article. The program allows you to export the measured values to a text file. In the last chapter of this work is made control measurements of three samples of monocrystal photovoltaic cell by the measuring workplace. The measurement is compared with the reference device Solar Cell Tester.