>Magister Scientiae - MSc / In a quest for low operational and maintenance cost solar cell devices, organic photovoltaics remain a potential source of energy worthy to be explored. In order to generate cost- effective electricity from solar energy, either the efficiency of the solar cells must be improved or alternatively the manufacturing cost must be lowered. The power conversion efficiency (PCE) of organic photovoltaics is influenced by the choice of electron acceptor material, the structure of the polymer, the morphology of the film, the interfaces between the layers and the ratio between the electron acceptor material and the polymer. Nevertheless, efficiency is still limited compared to conventional silicon based PV cells due to low mobility of charge carriers with a short exciton diffusion length in the active layer. Currently, hybrid solar cells have been considered as one of the most promising concepts to address the limited efficiency of organic solar cells. Therefore in this thesis ZnO nanoparticles were synthesized using hydrothermal assisted method. These nanoparticles were incorporated in the poly (3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM), and used as additional acceptors of electrons released from the polymer donor material, with the anticipation to increase the electron mobility, and ultimately the PCE. The thermo-gravimetric analyses revealed improved thermal stability of P3HT upon incorporating ZnO in the polymer matrix. X-ray diffraction analyses revealed that the diffraction peaks shift to higher angles when incorporating the ZnO in the P3HT:PCBM surface and this is consistent with the Raman observation. The photovoltaic properties demonstrated that the addition of ZnO nanoparticles in P3HT:PCBM bulk-heterojunction increases PCE from a baseline of ∼1.0 % in the P3HT:PCBM system to 1.7% in the P3HT:PCBM:ZnO ternary system. The enhanced PCE was due to improved absorption as compared to its counterparts. Upon increasing the addition of ZnO nanoparticles in the P3HT:PCBM matrix, the PCE decreases, due to a large phase separation between the polymer, PCBM and ZnO induced by ZnO agglomerations which resulted in increased surface roughness of the active layer. These findings signify that incorporation of ZnO nanostructures in the P3HT:PCBM polymer matrix facilitates the electron transport in the photoactive layer which results to improved efficiency.

Les cellules photovoltaïques organiques sont une technologie prometteuse pour répondre aux besoins futurs en énergie. Elles présentent de faibles coûts de production, peuvent être réalisées sur substrats flexibles et s'intègrent dans des dispositifs légers. Une voie d'amélioration du rendement de photoconversion est la conception de nouvelles molécules actives présentant des propriétés structurales optimisées. Le présent travail s'inscrit dans cette dynamique: sur la base de calculs utilisant la théorie de la fonctionnelle de la densité, de nouveaux semiconducteurs organiques ont été conçus puis synthétisés. Pour cela, des techniques de synthèses les plus économiques et les moins polluantes possible ont été mises en œuvre. Ainsi, le couplage du benzothiadiazole avec le thiophène carboxhaldéhyde par hétéroarylation directe sans additif ni ligand est utilisé avec succès pour la première fois selon des techniques de chimie verte. Cinq molécules sont ainsi isolées en seulement deux étapes. L'étude de leurs propriétés optiques et électroniques par différentes techniques spectroscopiques (UV/vis, fluorescence) et par électrochimie, de leurs propriétés thermiques, et de leur aptitude à s'auto-organiser ont permis de révéler leur aptitude prometteuse pour une utilisation en photovoltaïque organique. Une série de molécules dérivées du fragment dithiénosilole (DTS) ont été également étudiées par calculs de DFT. Les résultats obtenus montrent que ces dérivés présentent des largeurs de bande interdite très faibles, ce qui constitue un atout pour leur utilisation en cellule photovoltaïque. Ces résultats ont par conséquent motivé leur synthèse. Enfin, un travail purement théorique a été réalisé sur des molécules dérivées des subphthalocyanines de bore. Les calculs effectués révèlent des propriétés électroniques originales pour ces nouveaux matériaux qui devraient mener à des performances intéressantes pour le photovoltaïque organique, ouvrant ainsi la voie vers des matériaux innovants et prometteurs. / Organic solar cells appear as a promising technology to meet future energy requirements, owing to their low production costs, their great flexibility and their ability to be integrated into light devices. Currently, they exhibit modest performances in photoconversion, thus new active molecules with optimized structural properties need to be developed. This work comes in that aim: on the basis of theoretical calculations with density functional theory, new organic semiconductors have been designed and synthesized. For this, the more economical and cleaner syntheses techniques have been employed. Thus, the coupling of the benzothiadiazole with thiophene carboxhaldehyde via direct heteroarylation without additive nor ligand is performed with success for the first time. According to green chemistry techniques, five molecules are thus isolated in only two steps. The study of their optical and electronic properties by means of different spectroscopic techniques (UV/vis, fluorescence) and electrochemistry, of their thermal properties, and of their ability to self-organize have revealed their promising abilities for use in organic photovoltaics. A series of small molecules based on dithienosilole (DTS) core have also been designed via DFT computations. The calculations show their considerable low bandgap. Their syntheses have been conducted. It anticipates their promising potential for organic photovoltaic applications. Finally, a purely theoretical work has been completed on molecules derived from boron subphthalocyanines. The calculations predict interesting electronic properties for these new materials that may lead to promising performances in organic photovoltaics, paving the way for innovative materials.

During the 21st century there has been a rapid increase in grid-connected photovoltaic (PV) capacity globally, due to falling system component prices and introduction of various economic incentives. To a large extent, PV systems are installed on buildings, which means they are widely distributed and located close to the power consumer, in contrast to conventional power plants. The intermittency of solar irradiance poses challenges to the integration of PV, which may be mitigated if properly assessing the solar resource. In this thesis, methods have been developed for solar variability and resource assessment in the built environment on both national and local level, and have been applied to grid integration studies. On national level, a method based on building statistics was developed that reproduces the hourly PV power generation in Sweden with high accuracy; correlation between simulated and real power generation for 2012 and 2013 were 0.97 and 0.99, respectively. The model was applied in scenarios of high penetration of intermittent renewable energy (IRE) in the Nordic synchronous power system, in combination with similar models for wind, wave and tidal power. A mix of the IRE resources was sought to minimise the variability in net load (i.e., load minus IRE, nuclear and thermal power). The study showed that a fully renewable Nordic power system is possible if hydropower operation is properly planned for. However, the contribution from PV power would only be 2-3% of the total power demand, due to strong diurnal and seasonal variability. On local level, a model-driven solar resource assessment method was developed based on low-resolution LiDAR (Light Detection and Ranging) data. It was shown to improve the representation of buildings, i.e., roof shape, tilt and azimuth, over raster-based methods, i.e., digital surface models (DSM), which use the same LiDAR data. Furthermore, the new method can provide time-resolved data in contrast to traditional solar maps, and can thus be used as a powerful tool when studying the integration of high penetrations of PV in the distribution grid. In conclusion, the developed methods fill important gaps in our ability to plan for a fully renewable power system.

Down-conversion (DC) and down-shifting (DS) layers are optical layers mounted on the top surface of a solar cell that can potentially increase the solar cell efficiency. The effect of DC and DS layers to enhance the performance of single-junction solar cells has been studied by means of simulation and experimental work. In this thesis a model is developed to study the effects of DC and DS layers by modifying the incident spectrum. The effect of the layers on ideal cells as well as commercial grade silicon and CIGS solar cells that are modeled in a device simulator is examined. Silicon nanocrystals (Si-nC) embedded in a silicon dioxide matrix to act as a DS layer were fabricated and characterized at McMaster University as part of this project. The measured optical properties as well as the photoluminescence measurements are used as input parameters to the optical model. The enhancement due to the Si-nC when coupled to silicon and CIGS solar cells is explored. Beside the DC and DS effects, there is also disturbance to the surface reflections due to the addition of a new layer to the top surface and is referred to as antireflection coating (ARC) effect. For the simulated silicon solar cell under the standard AM1.5G spectrum (1000W/m2), a maximum increase in Jsc of 8.4% is achieved for a perfect DS layer as compared to a reference cell, where 7.2% is due to ARC effect and only 1.2% is due to DS effect. On the other hand, there is an increase in Jsc of 19.5% for the CIGS solar cell when coupled to a perfect DS layer. The DS effect is dominant with 18%, while the ARC effect contributes only 1.5% to the total Jsc enhancement. Accurately characterizing DS layers coupled to solar cell requires knowledge of optical properties of the complete structure. Internal quantum efficiency is an important tool for characterizing DS systems, nevertheless, it is rarely reported. In addition, the ARC effect is not experimentally decoupled from the DS effect. In this work, a straightforward method for calculating the active layer contribution that minimizes error by subtracting optically-modeled electrode absorption from experimentally measured total absorption.

Concentrator photovoltaics is a promising renewable energy technology, especially for utility or large-scale deployments. Like all new technologies, it has obstacles and setbacks to overcome. More specifically, the optics in a concentrator photovoltaics system introduce non-uniform spatial and spectral illumination on the cell, which can change under different operating conditions. This work was put together to discover a new characterization technique capable of analyzing the performance of a concentrator photovoltaics and provide insight to the field on what is happening within the system, linking modeling results seen in the literature to these experimental outcomes. The thesis is composed of three journal papers written by the candidate, who’s contributions are outlined at the beginning of each chapter. In order to study the illumination profiles on the cells, a new method to characterize the optical components had to be developed. Previous version lacked the ability to control the temperature of the lens and had low spectral resolution of the irradiance profiles. To improve, a novel indoor measurement method was developed capable of spectrally imaging concentrator photovoltaics optics and recreate outdoor operating conditions in a controllable environment. With the calibrated system, our test-bench is capable of measuring the spectral distribution with a 10μm2 resolution and characterizing the output of a system to within 3%. Exploiting this experimental technique, the individual effects of module misalignment, cell to primary distance, and lens temperature was studied for three leading technologies associated with the three generations of concentrator photovoltaics optical architectures. Focusing on Fresnel-based concentrator optics, the performance of silicone on a glass module without a secondary optic is the most sensitive to operating conditions, where lens temperature can decrease the absolute efficiency resulting in a difference of 11% in the annual energy yield. The next two generations have secondary optics but are designed slightly differently. The truncated inverted pyramid, designed independently of the primary optic, favoured higher lens temperature values and there was only a difference of 1% in the energy yield calculation. The primary and secondary optics in the 4-fold Fresnel-Kohler are designed together, due to new development tools, and showed the highest stability under the different operating conditions, demonstrating that concentrator photovoltaics is on the right track to overcoming its onset issue. As the technology matures, future designs can improve on the issues characterized within this thesis.

This masters thesis aims to assess and evaluate the potential of home based energy storage systems for the final user. In theoretical part it therefore describes the historical development of the European power sector with the purpose of determining, what was the impact of this development on products offered by energy providers to the final consumers of electricity. Findings from this analysis are then used to design a model, which is introduced and described in the practical part of the masters thesis. This model is afterwards used to assess the profitability of home batteries implementation by three different types of households and also to determine, what are the key drivers and constraints for the adoption of energy storage systems by households.

Syftet med denna studie är att identifiera vilka förutsättningar som kan ligga bakom en investering i solceller i Sverige. Studiens forskningsfråga lyder, Vilka förutsättningar kan påverka energiföretag till att investera i solcellsanläggningar? samt Vilka aspekter kan göra en solcellsanläggning mer lönsam? För att kunna besvara frågeställningarna har ett induktivt angreppssätt i studien använts, som utgör kvalitativa bestämmelser utifrån respondenternas information. I denna studie får läsaren bekanta sig med sex olika solcellsanläggningar belägna i olika delar av landet för att få en inblick i hur solcellsmarknaden fungerar idag. Experter med god uppfattning om solcellsmarknaden har intervjuats för att ge sin syn på marknadsutvecklingen och hur framtiden för solceller ser ut.   Sverige hade under 2015 en installerad solcellseffekt på 47,4 MW vilket motsvarar en ökning med 31 % jämfört med år 2014. Investeringsstöd och låga priser på solcellsmoduler utgör idag de två främsta motiven för aktörer som vill investera i solceller. Företag ser i samband med en solcellsinvestering goda möjligheter att stärka sin miljöprofil, vilket på senare år har visat sig vara en strategi som prioriteras högre än investeringens avkastning. / The purpose of this study is to identify in which conditions that may lie behind an investment in photovoltaics in Sweden. The study’s research questions are What conditions may affect an energy corporation to invest in photovoltaic facilities? and What aspects can make a photovoltaic facility more profitable? An inductive approach has been used in this study in order to answer the research questions, which make qualitative regulations that are taken from the respondents’ information.  The reader will get to know about six different photovoltaic facilities that are placed around different areas in Sweden to get an insight on how the present market for photovoltaics works. Experts with solid competence about the market has been interviewed in order to provide a view on how the future holds for the development on the photovoltaic market. Sweden had during 2015 47,4 MW installed photovoltaic effect which results in an increase by 31 percent compared to 2014. Investment support and low prices on photovoltaic modules are one of the motives for operators to invest in photovoltaics. In a company’s point of view there’s a connection with photovoltaic investments which creates great opportunities to strengthen the brand’s image for sustainable development, which in recent years looks to be a strategy that holds a higher priority than the profit itself.

Because of global warming and the Paris agreement from 2015, countries need to switch their energy sources into clean sources. For some countries, like Perú, electricity produced from renewable energy sources is still a new technology. Its electricity demand depends entirely on traditional hydropower and thermal plants. Despite the high solar radiation in the coast and Andes (mountain range that passes through the entire South American continent), solar electricity is not developed and it fairly reaches the 1% of the national electricity production. Sweden, similarly, also produces its highest share on electricity from hydropower. However, nuclear energy and renewables like biomass and wind cover the rest of the demand, compared to thermal plants for Perú. On the other hand, most of the poor citizens of Perú live in the Andes, especially in remote villages, disconnected from the national grid and suffering from the cold during winter. Because their energy demand is low, it is not profitable for the electrical companies to give them electricity. The Swedish population, however, has 100% access to electricity. Despite that, high prices on maintaining the connection to the electricity network, and constant failures because of bad weather (more common nowadays because of global warming), brings the idea to disconnect from the grid and produce one´s own electricity, with, for example, photovoltaic systems. These problems occur not exclusively in Sweden. The work done on this thesis consists on a design of an off-grid solar PV system using batteries for energy storage, both for a remote farmer village in the high Andes in Perú (Ungalluta 2) and for a rural, low populated village in the center of Sweden (Gåsborn). The design is done manually and by software (PVSyst), with real life components, analyzing costs and the possibility to live entirely on solar power. The priority when choosing the components is the lowest price. For Ungalluta 2, with a demand of 17.1kWh/d (11 people), 13 PV modules and 1600Ah of battery capacity (Lead Acid) are needed, with a payback in approximately 40 years, renewing the PV panels on year 25 because of degradation. The initial investment is 21540EUR. For Gåsborn, with a demand of 36.44kWh/d (average Swedish family with children), 42 PV modules and 2850Ah of battery capacity (Lithium) are needed, with a negative payback, even increasing the PV modules to cover the entire year (more than 400). This is because the solar irradiation is quite low during winter and the load demand needs to be satisfied with considerable amounts of Diesel with a backup generator. After analyzing the results, it is possible and viable to build PV systems for the villagers in the Andes of Perú, but they will need monetary help of the government (high initial cost). For Sweden, it is not profitable to depend entirely on PV power. Other renewable sources must complement it, such as wind, to compensate the low solar irradiation and reduce the diesel consumption. / På grund av global uppvärmning och Parisavtalet från 2015, måste länderna byta sina energikällor till förnybara alternativ. För vissa länder, som Perú, är el från förnybara källor fortfarande en ny teknik. Dess elbehov beror helt och hållet på traditionella vattenkraftverk och termiska anläggningar. Trots den höga solinstrålningen vid kusten och i Anderna (bergskedja som går genom hela den sydamerikanska kontinenten) är el från PV inte utvecklad och den täcker knappt 1 % av den nationella elproduktionen. Sverige producerar på motsvarande sätt sin högsta andel av el från vattenkraftverk. Den resterande delen av elbehoven täcks av kärnkraftverk och förnybar energi som biomassa och vindkraft jämfört med de termiska anläggningarna i Perú. De flesta fattiga invånarna i Perú bor i Anderna, särskilt i avlägsna byar, bortkopplade från det nationella elnätet och blir således lidande under de kalla vintrarna. På grund av deras låga energibehov är det inte lönsamt för elföretag att förse dem med elektricitet. I Sverige är det dock annorlunda. Befolkningen har 100 % tillgång till elektricitet. Trots det är priserna för underhåll av anslutning till elnäten höga och återkommande strömavbrott på grund av dåligt väder är vanligt, särskilt på landsbygden. Detta ger upphov till idén om att koppla bort från nätet och producera egen elektricitet med exempelvis solcellssystem. Arbetet i denna uppsats består av en konstruktion av ett off-Grid system med solceller som använder batterier för energilagring, både för en by högt upp i Anderna i Perú (Ungalluta 2) och för en mindre befolkad by på landsbygden i mitten av Sverige (Gåsborn). Systemen är beräknade både för hand och med mjukvara (PVSyst) med verkliga komponenter för att analysera kostnaden och möjligheten att helt och hållet leva på solenergi. Vid val av komponenterna har lägsta pris varit en prioritering. För Ungalluta 2, med ett behov på 17.1 kWh/d (11 personer), behövs 13 solcellsmoduler och en batterikapacitet på 1600Ah (Bly-syra). Den ursprungliga investeringen uppgår till 21540 EUR och återbetalningstiden till 40 år där modulerna byts ut efter 25 år på grund av degradation. För Gåsborn, med ett behov på 36.44 kWh/d (genomsnittet for en Svensk familj med barn), behövs 42 solcellsmoduler och en batterikapacitet på 2850Ah (Litium) vilket ger en negativ återbetalning även om solcellsarean ökas för att täcka hela året (mer än 400 solcellsmoduler). Detta beror på att solinstrålningen är låg under vintern och att behovet måste täckas med stora mängder diesel och med en backupgenerator. Efter att ha analyserat resultatet är det möjligt och genomförbart att bygga solcellssystem för de byborna i Anderna i Perú men de kommer att behöva kapital från regeringen (hög initial kostnad). För Sverige, är det varken lönsamt eller miljövänligt att vara helt beroende på solenergi utan andra förnybara källor så som vind måste komplettera den för att kompensera den låga solinstrålningen och för att reducera dieselförbrukningen.

This thesis work’s purpose is to collect, analyze, and display data from a PV array located in Borlänge, Sweden. For the data analysis, MATLAB is used as an analysis tool, in order to have an idea of how the system is going in its entirety by drawing several different graphs such as daily irradiance or temperature but also to gather all the data that is available and regroup it in the same Excel sheet in order to simplify the usage of the program. For the display of the data, Excel Visual Basics for Applications (VBA) is used to establish a user-controlled interface which lets the choice to study a certain parameter over a certain period of time, and then display graphs and data automatically, all of this being chosen by the user, for example to create daily, monthly or yearly plots of the energy production as well as the efficiency of the system.

The sun is the foundation of all life on earth. The potential regarding solar energy is relatively good in large parts of southern Sweden. Sweden has set an environmental goal that states that their electrical production will be generated from 100% renewable energy sources by 2040 at the latest. In order to achieve this goal, there will need to be extensive expansion of wind parks as well as solar parks. Sweden has not had the same development as Germany regarding the expansion of solar energy. The authors suggest that there is a need to investigate what factors influence the expansion of photovoltaics parks and what barriers are in the way of achieving large scale solar electricity production. The thesis will focus on solar expansion within the manufacturing sector as well as the agricultural sector within Halland county. The authors of this thesis aim to investigate the economic and administrative factors that influence investment opportunities alongside other factors that influence the expansion of solar energy. The study’s goal is to answer two research questions: “What factors are the most important to achieve large scale expansion of solar energy on manufacturing facilities and agricultural facilities?” “Which instruments and actions are required from society’s standpoint to enable large scale expansion of solar electricity production on manufacturing facilities as well as agricultural facilities in the county of Halland? “ The methodology used in this thesis is a qualitative approach where semi constructed interviews were implemented. There were six respondents that participated in the study. Whereas half were companies within the manufacturing industry or the agricultural sector, the rest were individuals within the field of solar energy. By conducting this study, several factors were identified that either promoted or hindered solar production within Halland county. The most prominent factors which drive development were economic and environmental factors, whilst laws and the investment cost was biggest factors that hindered development. In conclusion, the study suggests that there are changes in laws that need to be implemented to achieve large scale solar production within Halland county.