As part of the SUNRISE project (Semiconductors Using Nanostructures for Record Increases in Solar-cell Efficiency), high efficiency, III-V semiconductor, quantum-dot-enhanced, triple-junction solar cells designed and manufactured by Cyrium Technologies Inc. were integrated into OPEL Solar, MK-I, Fresnel-lens-based, 550x concentrating modules carried on a dual axis tracker. Over its first year of operation 1.8 MWh of AC electrical energy was exported to the grid. Measurements of the direct and indirect components of the insolation, as well as the spectral irradiance of light incident on the demonstrator in Ottawa, Canada are presented. The system efficiency is measured and compared to that predicted by a system model to identify loss mechanisms so that they can be minimized in future deployments.

A novel approach to the design of multi-junction solar cells on silicon substrates for 1-sun applications is described. Models for device simulation including porous silicon layers are presented. A silicon bottom subcell is formed by diffusion of dopants into a silicon wafer. The top of the wafer is porosified to create a compliant layer, and a III-V buffer layer is then grown epitaxially, followed by middle and top subcells. Due to the resistivity of the porous material, these designs are best suited to high efficiency 1-sun applications. Numerical simulations of a multi-junction solar cell incorporating a porous silicon compliant membrane indicate an efficiency of 30.7% under AM1.5G, 1-sun for low threading dislocation densities (TDD), decreasing to 23.7% for a TDD of 10^7 cm^-2.

Photovoltaic (PV) solar panels and trackers represent one of the most common renewable energy technology which converts sunlight radiation into electrical energy. The solar trackers specifically are more complex structures because they involve mechanical devices, a supporting slender structure, and photovoltaic modules mounted and positioned on top of the supporting structure. Solar trackers are mounted on mobile supports or racks, in order to enable the rotation and tilt of the PV which thus maintains their optimum exposure to the incident sunlight. Solar trackers support structures should be designed for wind resistance during the operation and at stow position for its life span and this became a concern considering the new tendency of installing the solar trackers on the rooftop of low-rise or medium-rise buildings. The current research focused on performing site measurements of the wind-induced displacement for a dual-axis solar tracking system installed on the roof of the Mann Parking building of the University of Ottawa, for different azimuth, elevations. The supporting structure of the solar tracker was instrumented with 16 strain gauges and the strains developed in the metal truss members were measured during the months February 2015 and March 2015. The tracker was rotated and tilted at different angles through the duration of the experiment and the strains observed on each structural element were recorded. In order to estimate deflections of the supporting structure for wind speeds higher than the ones measured, a finite element (FE) model of the solar tracker was created and static analysis was performed for different inclinations using the SAP 2000 structural software. The experimental results were in agreement with the FE simulation results as the stresses obtained ranged between 1.02 × 107 Pa and 7.88 × 107 Pa. Lower attack angles between 45° and 60° were found to have significant effect on the elements of the solar tracker irrespective of the wind load magnitude. Operational attack angles between 65° and 75° were found to be safer positions as obtained displacements and stress analysis result showed that the supporting structure of the solar tracker was stable for wind speeds between 0 m/s and 33m/s in Ottawa region

Le travail présenté dans cette thèse concerne l'amélioration de la stabilité de cellules photovoltaïques organiques à base de poly(3-hexylthiophène) : [6,6]-phényl-C61-butanoate de méthyle (P3HT:PCBM) par des réseaux semi-interpénétrés de polymères (semi-RIP).La couche photoactive d'une cellule solaire organique forme une hétérojonction volumique entre un matériau donneur et un matériau accepteur d'électrons. Pour un effet photovoltaïque performant, sa morphologie doit non seulement être optimisée mais également être conservée et éviter ainsi une micro-séparation de phase thermodynamiquement favorable entre les deux matériaux qui serait néfaste aux performances photovoltaïques du dispositif.De plus, la couche tampon de poly(3,4-éthylène dioxythiophène) : polystyrène sulfonate (PEDOT:PSS) possède une acidité néfaste pour l'anode à base d'oxyde d'indium et d'étain (ITO). Ceci représente un autre facteur de dégradation des cellules photovoltaïques.Dans le cadre de nos travaux, nous avons choisi d'utiliser une structure de référence (ITO/PEDOT:PSS/P3HT:PCBM/Al) auquel nous proposons des modifications par formation de semi-RIP au niveau de la couche de PEDOT:PSS ou au niveau de la couche photoactive (P3HT:PCBM).Dans un premier temps, nous nous sommes intéressés à la formation d'un semi-RIP dans la couche de PEDOT:PSS grâce un réseau de polyoxyde d'éthylène (POE). Enfin dans un second temps, l'étude de semi-RIP à base de polyméthacrylate (de butyle ou de lauryle) dans la couche active pour l'amélioration de la durée de vie des dispositifs a été réalisée. Au cours de ces travaux, des analyses de dégradation photochimique, de dégradation thermique ou encore de vieillissement dans des conditions de température ambiante ont montré une amélioration de la durée de vie des dispositifs. / This thesis relates to improving the stability of organic photovoltaic solar cells based on poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) by semi-interpenetrating polymer networks (semi-IPN).The photoactive layer of an organic solar cell forms a bulk heterojunction between a donor material and an electron acceptor material. For efficient photovoltaic effect, morphology should not only be optimized but also be maintained in order to avoid a micro-phase separation thermodynamically favorable between the two materials that would be detrimental to the photovoltaic device performance.Moreover, an other factor of degradation of the photovoltaic cells may be the acidity of the buffer layer of poly (3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT: PSS) to the anode based on indium and tin oxide (ITO).In the framework of our study, a reference structure (ITO/PEDOT: PSS/P3HT:PCBM/Al) was chosen and modified by forming semi-IPN in the layer of PEDOT:PSS or in the active layer (P3HT: PCBM).At first, the formation of a semi-IPN in the layer of PEDOT: PSS through a network of polyethylene oxide (PEO) was developed. Finally, in a second time, the study of semi-IPN based on polymethacrylate (butyl or lauryl) in the active layer to improve the lifetime of the devices was carried out. In this research, analyzes of photochemical degradation, thermal degradation or aging under conditions of room temperature showed an improvement of the devices lifetime.

Goal of this thesis is to analyse sequence of events that led to current situation on the solar market in Czech Republic. Based on this analysis, current situation and scenarios for the near future from the point of view of large power utility company are described. For this aim, analysis of macro-environment is employed and focuses in detail on legislative and technological factors. Definition of possible scenarios starts with the description of current situation of saturated market. Solar power plants are then presented as reasonable equity investment from the point of view of large power utility company. Assumptions and entry data are described and the investment is evaluated using the net present value evaluation tool. For chosen entry parameters, sensitivity analysis is performed. This thesis then defines the situation when electricity produced from solar irradiation becomes competitive with other conventional sources.

The thesis evaluates the principal business-related and logistical opportunities and risks on the African solar market which is often associated to offer the last unexploited economic opportunities on this planet. For this purpose, the author examines three major African trade unions and reviews the strengths and weaknesses of each regional coalition. It becomes obvious that each respective trade bloc contains one dominant player, in this case Nigeria, Kenya and South Africa. The practical section starts with an analysis of the appropriate entry market for the Czech solar wholesaler Solarity. Subsequently, the author identifies South Africa as the best fitting market primarily because of good infrastructure, high purchasing power and a similar business culture. The author recommends that Solarity should apply an exporting entry mode due to its size and inexperience on the African market. Secondary research, first-hand experience and close cooperation with Solarity support the author in his final conclusions.

Dans le domaine du photovoltaïque, les cellules hybrides organiques sont une des voies les plus prometteuses, notamment grâce aux propriétés de collection de lumière des molécules de type chromophore. Les nanotubes de carbone, quant à eux, sont des nano-objets quasi unidimensionnels qui présentent des propriétés de transport exceptionnelles. La réalisation d’un couplage important entre une molécule collectrice de lumière et un nanotube de carbone représente donc une voie importante à explorer. Ce travail de recherche est consacré à l’étude du transfert d’énergie dans les composés nanotubes de carbone/chromophore. Une nouvelle méthode de fonctionnalisation non covalente des nanotubes de carbone est présentée. Basée sur une suspension micellaire de nanotubes, cette méthode permet d’obtenir un fort taux de fonctionnalisation tout en préservant les propriétés intrinsèques des nanotubes. Le transfert d’énergie est mis en évidence sur les composés nanotube/porphyrine par des mesures d’excitation de la photoluminescence sur ensemble de nanotubes ainsi que sur objets uniques. L’évaluation du rendement quantique de transfert par trois méthodes indépendantes montre un couplage de l’ordre de 100% entre la molécule et le nanotube- et ce malgré la faiblesse des interactions entre orbitales «Pi» mises en jeu dans la fonctionnalisation non covalente. Le dernier volet de ce travail est consacré à des mesures d’anisotropie à l’échelle de l’objet unique permettant d’obtenir des informations quant à l’arrangement des molécules à la surface des nanotubes. / In the field of photovoltaic, hybrid organic solar cells are one of the most promising ways, especially due to the light collection properties of chromophore molecules. On the other hand, carbon nanotubes are quasi one-dimensional nano-objects showing exceptional transport properties. The achievement of a significant coupling between a light harvesting molecule and a carbon nanotube is an important route to explore. This research is dedicated to the study of energy transfer in carbon nanotube/chromophore compounds. A new method of non-covalent functionalization of carbon nanotubes is presented. Based on a micellar suspension of nanotubes, this method provides a high degree of functionalization while preserving the intrinsic properties of nanotubes. The energy transfer is shown in nanotube/porphyrin compounds by photoluminescence excitation spectroscopy on ensembles as well as at the single molecule scale. The evaluation of the quantum efficiency of the transfer by three independent methods shows a coupling of the order of 100% between the molecule and the nanotube, despite the weak interactions between “Pi” orbitals involved in the non-covalent functionalization. The final part of this work is dedicated to anisotropy measurements on single compounds to gain information on molecular arrangement on the surface of nanotubes.

Thesis (M. Sc. (Physics)) -- University of Limpopo, 2016 / Titania is a cheap and nontoxic polymorphic material of current interest for a variety of technological applications like in gas sensing and photovoltaic cells. Generally, TiO2, with a band gap of 3.2 eV, can only be excited by a small UV fraction of solar light, which accounts for only 3-5% of the solar energy. Various strategies have been pursued including doping with metallic elements (e.g. Fe) or nonmetallic elements (e.g. N) with the aim of shifting the absorption into the visible range. Since the properties and performance of devices, particularly for high-temperature applications, may be affected by the transformation from one phase to another, it is of significant interest to understand the conditions that affect phase transitions. In the present work TiO2 was doped with platinum (Pt), palladium (Pd), silver (Ag) and gold (Au) at doping levels of 5% weight, following the standard sol-gel methods. Structural characterization was carried out using scanning electron microscopy, Raman Spectroscopy and X-ray diffraction. Optical properties were studied using the Diffused reflectance Spectroscopy (DRS). Doping with Pt and Pd resulted in a lower anatase to rutile phase transformation temperature while doping with Au and Ag did not affect the transformation temperature. SEM micrographs show that the surface contains irregular shaped particles which are the aggregation of tiny crystals at lower temperature range, whereas at higher temperatures (900 °C), spheroids are observe.The reflectance spectra of the metal loaded TiO2 reveal substantial strong spectral cut-off starting from roughly 400 nm to the entire visible region (i.e. they show enhanced absorption).

<p>Land use constraints have motivated investigation into the spatial coexistence of solar photovoltaic electricity production and agricultural production. Previous work suggests that agriculture-photovoltaic (agrivoltaic) systems either decrease crop yield or are limited to shade-tolerant crops. Existing experimental work has also emphasized fixed south-facing configurations with traditional commercial panel shapes, and modeling work is sparse. In this work, the effects of different photovoltaic array configurations and panel designs on field insolation spatial and temporal variation are explored in detail to determine photovoltaic design routes that may increase expected crop yield in agrivoltaic systems. It is found that photovoltaic row orientation is the most influential factor on insolation homogeneity due to shadow migration paths. Additionally, it is shown that utilization of mini-modules in patterned panel designs may create more optimal conditions for plant growth while using the same area of PV, thus improving the land efficiency ratio of the agrivoltaic system. Different solar tracking algorithms are explored to optimize the trade-off between electricity production and expected crop growth. The feasibility of select agrivoltaic systems is explored for multiple U.S. locations. This thesis concludes with recommendations for photovoltaic system designs corresponding with specific crop growth considerations.<br></p>

Photovoltaic (PV) technology using organic solar cells have attracted much attention, as it is a simple and efficient way to convert solar energy into usable electricity. At present, bulk­heterojunction (BHJ) organic solar cells, which are based on conjugated p­type polymers and n­type fullerene derivatives, have been intensively investigated in both academia and industry. Organic and metallated conjugated small molecules (SM) represent an intriguing and promising class of materials. Atomic­thick 2D nanosheets have attracted tremendous attention recently because of their novel electronic structures and physical properties. This thesis describes the synthesis and characterization of some series of organic and metallated aryleneethynylenes and their applications in BHJ solar cells. To begin with, a brief overview on the background of organic solar cells (OSCs) and two­dimensional (2D) nanomaterials was presented in Chapter 1. In Chapter 2, a new series of multichromophoric small molecular systems of ruthenium(II)­bis(aryleneethynylene) compounds containing triphenylamine and/or thiophene as the donor and benzothiadiazole as the acceptor were designed and obtained by straightforward synthesis and purification procedures with reasonable yields. These ruthenium complexes absorb strongly in the visible region which are potentially attractive materials for photovoltaic cell applications. The best power conversion efficiency (PCE) of 0.66% was achieved for D1 with the open­circuit voltage (Voc) of 0.51 V, short­circuit current density (Jsc) of 4.24 mA cm­2 and fill factor (FF) of 0.31 under illumination of an AM 1.5 solar­cell simulator. Furthermore, in Chapter 3, a new series of small molecular systems of platinum­containing organometallic conjugated molecules containing different donating groups (such as thiophene, BDT, carbazole, and bithiazole), benzothiadiazole and/or dimesitylborane as the acceptors were successfully designed and obtained. Among all the BHJ devices based on these platinum complexes, PT5­based device, which we introduced strong donor group carbazole in the molecule, showed the highest PCE of 1.46% with high Voc of 0.70 V, Jsc of 6.17 mA cm­2 and FF of 0.33 at the optimized active layer thickness of 60 nm, which indicates that the photovoltaic performance can be significantly improved by introducing a strong D group in the molecule. Besides, a new series of organic small molecules M1­M16 of D­A­spacer­A­D structure were successfully designed and obtained. Intramolecular charge transfer (ICT) effect could be observed due to the strong electron­withdrawing units (such as benzothiadiazole, DPP, trizaole and dimesitylborane) and strong electron­donating units (such as triphenylamine, thiophene, BDT, carbazole, and bithiazole), and this effect between the acceptor and donor units causes low bandgap. By introducing strong oligothiophene donor group in the molecule M4, which showed the highest PCE of 3.68% among all the devices with high Voc of 0.95 V, Jsc of 7.76 mA cm­2 and FF of 0.44 at the optimized active layer thickness of 75 nm, which also indicates that the photovoltaic performance can be significantly improved by introducing a strong D group in the molecule. In Chapter 5, we designed and synthesized a new series of the “bottom­up” metal complex nanosheets: p­conjugated bis(dipyrrinato) metal complex nanosheets, including monolayer and multilayer nanosheets. AFM, IR, XPS and SEM analyses have been applied to study the morphologies, chemical state and size or nanostructure of the as­prepared nanosheets, and the results indicated that the “bottom­up” method is useful for the construction of photoresponsive and semiconductive nanosheets. This work is going to enlarge the futurity of the “bottom­up” nanosheet as next­generation nanomaterials. Finally, Chapters 6 and 7 present the concluding remarks and the experimental details of the work described in Chapters 2­5.