This report presents a master's thesis conducted within the machine design track at KTH Royal Institute of Technology. The research work was undertaken in collaboration with Novige AB, who commissioned the project. Novige AB is in the development and testing phases of a wave energy converter (WEC) of which exhibits a large area of unutilized potential. This led to the purpose of this thesis, conceptualizing a support structure and expanding mechanism for solar panels to be mounted on the float of the WEC. Since no previous work related to the subject had been conducted, the objectives were to explore different solutions and present a detailed final concept, including initial finite element calculations from expected load cases. The work consisted of several concept phases to ensure a thorough design process and to be able to accurately evaluate each concept. The outcome of the project yielded a conceptual design, featuring stackable solar panel modules. Each module consisted of four panels arranged horizontally and three panels vertically, resulting in a total of 288 solar panels, when incorporating eight modules on each float. The cumulative potential maximum power output of the configuration was estimated to be approximately 115 kW. When harsh conditions would be detected, the outer modules would retract under the fixed center module. To support the outer modules, a telescope beam was incorporated, spanning the outermost points of the structure, while roller guides were utilized at the inner end. Moreover, the movement of the outer modules was facilitated by a chain mechanism, housed within a U-profile. Most components in the design were proposed to be manufactured using steel, supplemented with protective measures such as paint or coating to ensure durability in the oceanic environment. / Denna rapport presenterar ett mastersarbete som utförts inom maskinkonstruktionsspåret vid KTH Kungliga Tekniska Högskolan. Arbetet genomfördes i samarbete med Novige AB, som beställde projektet. Novige AB befinner sig i utvecklings- och testfaserna av ett vågkraftverk (WEC) som har en stor outnyttjad yta med potential. Detta ledde till syftet med detta arbete, att konceptualisering en stödstruktur och en expanderingsmekanism för solpaneler som ska monteras på flotten av WEC. Eftersom ingen tidigare forskning hade utförts på området var målet att utforska olika lösningar och presentera ett detaljerat slutkoncept, inklusive initiala beräkningar med FEM under förväntade lastningsfall. Arbetet bestod av flera konceptuella faser för att säkerställa en noggrann designprocess och för att kunna utvärdera varje koncept på ett genomgående sätt. Projektet resulterade i en konceptuell design med stapelbara solpanelesmoduler. Varje modul höll 12 solpaneler, fyra horisontellt och tre vertikalt med 3 moduler per struktur. Varje WEC kunde bära totalt 8 strukturer vilket ger 288 solpaneler per WEC. Den sammanlagda potentiella effekten för konfigurationen uppskattades till cirka 115 kW. Vid svåra väderförhållanden, skulle de yttre modulerna dras tillbaka under den fasta mittmodulen för att minska vindfånget. För att stödja de yttre modulerna inkluderades en teleskopisk balk som bär de yttersta punkterna på modulen, medan rullstöd användes i den inre delen. Dessutom utfördes rörelsen hos de yttre modulerna av en kedja-kuggmekanism som placerades inuti en U-profil. De flesta komponenter i designen föreslogs tillverkas av stål, kompletterat med skyddsåtgärder såsom färg eller beläggning för att minimera risken för korrosion i den marina miljön.

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Due to a rising land demand for the construction of large-scale PV-systems, there is increasing competition between energy and food production. A new emerging segment within the PV market called agrivoltaics is providing a contributing solution to this issue by co-using the land for both crop cultivation and PV energy. Agrivoltaics is a relatively new application in Sweden, so far there is only one research site in Kärrbo Prästgård, Västerås, which was built in 2020. This thesis aims to examine how the basic layout of a PV system affects the irradiance distribution of an agrivoltaic system located in Sweden. With the aim of reaching an effective light sharing to provide the crops with acceptable growing conditions while producing as much electricity as possible. Methodologically, this was done by performing optical light simulations for a big number of different PV layouts. The results show how the module row distance and the array height have the most significant influence on the total irradiance distribution throughout the year. Furthermore, by altering the clearance height and the system azimuth, the irradiance uniformity on the ground can be improved, which results in more similar growing conditions for all the cultivated crops. Arguments are also given for why it is helpful to consider the temporal distribution of the ground irradiance. This thesis has shown that there are PV system layouts that provide low degrees of shading for the crops cultivated on the ground beneath the modules. However, if agrivoltaics is a suitable application for the Swedish climate or not is still an open question. Economic analysis is needed to examine the profitability of agrivoltaic systems in Sweden, and experimental studies on how the shading from the PV modules affect the crop growth in practice would also be useful. In the result section, there are some example layouts given for different degrees of tolerated ground shading which can be used when planning for future agrivoltaic parks. The results generated in the optical light simulations will be accessible for future research. These data files can be found attached together with this report on the DiVA portal.

Fault detection in PV systems is a key factor in maintaining the integrity of any PV system. Faults in photovoltaic systems can cause irrevocable damages to the stability of the PV system and substantially decrease the power output generated from the array of PV modules. Among'st the various AC and DC faults in a PV system, the clearance of the AC side faults is achieved by conventional AC protection schemes,the DC side, however , there still exists certain faults which are difficult to detect and clear. This paper deals with the modeling, detection and classification of these types of DC faults. It is essential to be able to simulate the PV characteristics and faults through software. In this thesis a comprehensive literature survey of fault detection methods for DC side of a PV system is presented. The disparities in the techniques employed for fault detection are studied . A new method for modeling the PV systems information only from manufacturers datasheet using both the Normal Operating Cell temperature conditions (NOCT) and Standard Operating Test Conditions (STC) conditions is then proposed.The input parameters for modeling the system are Isc,Voc,Impp,Vmpp and the temperature coefficients of Isc and Voc for both STC and NOCT conditions. The model is able to analyze the variations of PV parameters such as ideality factor, Series resistance, thermal voltage and Band gap energy of the PV module with temperature. Finally a novel intelligent method based on Probabilistic Neural Network for fault detection and classification for PV farm with string inverter technology is proposed.

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Meeting electricity demand and power shortage remains as a challenge to the people of the Gambia. As the country is undergoing tremendous electricity accessibility expansion [1], to secure the environment for the future generation, it is necessary to consider renewable energy to be the major source of electricity production, to be specific, solar energy. This is because the country experiences the radiation from the sun throughout the year, it is sustainable not only to our environment for the future generations, but also economically. However, due to the intermittent nature of most renewable energy technologies, it is cumbersome to rely on them 100 % as a primary source of electricity production. Nonetheless, with suitable storage technologies, combination of different renewable sources, and intercountry grid connections can enhance to overcome this challenge. In this thesis work, designed and techno economic evaluation was carried out for high PV penetration that will meet 50 % electricity demand of the Gambia in year 2040. Three scenarios were considered in this study, based on the Strategic Electricity Roadmap 2020 to 2040 [1]. These scenarios are high, universal access (AU), and low electricity demand. Economically, 50 % electricity supply to meet the demand is possible for all the three cases. Consideration was mainly put on four key figures, thus, levelized cost of electricity (LCOE), payback period (PBP), net present cost (NPC) and solar fraction (SF). To achieve 50 % SF for the high electricity demand scenario, LCOE and PBP are 0.129 $/kWh and 12 years respectively. As for AU electricity demand case, 50 % SF is achieved with 0.126 $/kWh and 10 years for LCOE and PBP respectively. For low electricity demand scenario, 0.127 $/kWh and 10 years for LCOE and PBP respectively for 50 % SF. However, the optimum design recommended by HomerPro were 45 % SF with LCOE of 0.126 $/kWh and PBP of 9 years for high electricity demand scenario. As for the AU electricity demand case, the optimum design is 48 % SF, LCOE of 0.125 $/kWh, and PBP of 9 years. In the last scenario, which is low electricity demand case, 46 % SF, 0.124 $/kWh LCOE, and 9 years PBP.

Recently, there has been a shift in the global healthcare paradigm, which is prioritizing a more patient-centric approach causing an increase in the demand for rapid and point-of-care (PoC) biomolecular detection. Electrochemical (EC) signal transduction has been used to great effect to meet some of this demand by constructing biosensors with high sensitivity and low limit-of-detection (LOD). However, signal generation in EC biosensors requires input bias potentials to activate electrochemical redox reactions. This means EC systems are inherently built-in with high background noise that limits the performance of biosensors. Biosensors with photoelectrochemical (PEC) signal transduction have recently shown great promise in being able to deliver biomolecular detection on par with, if not better than, EC biosensors. PEC biosensing directly improves upon EC signal transduction by combining EC signal readout with optical excitation as the bias input, and generally being able to achieve similar performance with simpler bioassay designs. In this scheme, the input and output of the signal transduction are decoupled from each other, significantly reducing background signal in biosensors to enhance their sensitivity. Despite being highly effective, PEC biosensors have yet to find commercial breakthrough as they have so far only shown quantitative analysis on a limited set of biomarkers and have not shown to be PoC-capable. In this thesis, we developed new strategies to improve PEC signal transduction so that it could be applied to build robust ultrasensitive PoC biosensors with high dynamic range, simple operation, and low LOD for detecting a wide variety of different disease biomarkers. The most popular photoactive materials used in the fabrication of PEC biosensors are TiO2 nanomaterials on account of their availability, chemical stability, high catalytic efficiency, tunable morphology, and ideal band energy levels for driving useful EC reactions. However, unmodified TiO2 suffers from several drawbacks that limit its photocurrent generation efficiency, such as poor visible range absorbance due its wide bandgap and fast charge carrier recombination. Alongside the additional difficulty of biofunctionalization, PEC biosensors fabricated from TiO2 nanomaterials are limited in their bioanalytic performance. In order to make improvements on PEC biosensors, we modified the surface of TiO2 nanomaterials by chelating them with catecholate molecules. The surface modification with catecholates formed charge transfer complexes on TiO2, which resulted in enhanced photoexcitation due to enhanced electron injection attributable to intermolecular orbital excitations in the catecholate molecules. The catecholate ligands also added improved colloidal stability and additional functional groups that aided with biofunctionalization. This resulted in multifunctional TiO2 nanoparticles with improved photocurrent signal generation and enhanced visible range photoabsorption. We took this one step further by taking advantage of the high binding affinity of catecholates on TiO2 surfaces to create novel synthesis methods that created high surface area nanostructures. Photoelectrodes fabricated from these new TiO2 nanostructures had nanoporous morphology and were able to capture biomolecules more efficiently. Using our novel TiO2 nanomaterials, we fabricated signal-off biosensors that were able to detect DNA biomarkers and IL-6 protein (cancer and inflammatory biomarker) in urine with an LOD of 1.38 pM and 3.6 pg mL-1, respectively. We further explored hybrid semiconductor structures by combining TiO2 nanomaterials with other materials such semiconductors with different bandgaps or plasmonic metal nanoparticles (NP). Using the aforementioned catechol-assisted synthesis techniques, we were able to produce different morphologies of TiO2 nanomaterials with distinct phases: anatase TiO2 nanorod assemblies and rutile TiO2 NP. The two different TiO2 nanomaterials have different bandgaps and can be used to form semiconductor heterostructures. By combining rutile TiO2 NPs with DNAzymes, a type of synthetic functional nucleic acid, we created a photoactive molecular switch that worked by making and breaking heterostructures between the two TiO2 nanomaterials. We used DNAzymes specific to E. coli bacteria to develop a highly sensitive signal-on bacterial detection platform that was able to detect E. coli in lake water samples with an LOD of 18 CFU mL-1. Using catecholate-assisted photoreduction synthesis, we developed an efficient and novel method for decorating TiO2 NP with silver (Ag) NP. The resultant nanomaterial featured TiO2 NP surfaces modified with Hematoxylin (HTX) dyes and covered with sub-nanometer sized silver NP. The band structure of TiO2/HTX/Ag NP hybrid material involved high energy electron generation through decay of surface plasmons in the Ag NP and then enhancing the photoelectron injection process between HTX and TiO2. This significantly enhances the photoexcitation and photoabsorbtion, resulting in the material with the highest photocurrent generation as presented in this thesis. By taking advantage of thiol-metal bonds, we used the TiO2/HTX/Ag NP material system in the fabrication of a highly sensitive signal-off microRNA (prostate cancer biomarker) sensor with an LOD of 172 fM in urine. Special attention was paid to the design of PEC bioassays in this work so that they are miniaturized and easy to use, and thus suitable for PoC applications. Because PEC signal transduction generates ultrahigh signals compared to other transduction methods, it allows bioassay designs to remain simple without sacrificing performance. This allowed us to create bioassays with very few operational steps, that excel in reliability and ease-of-use. To further improve PoC capability, we explored multiplexing with the biosensor made from TiO2/HTX/Ag NP. Here we were able to demonstrate multiplexing with PEC signal transduction for the first time. Another major barrier to PEC biosensors becoming widespread is the requirement of large benchtop instrumentation such as potentiostats and light sources. To address this challenge, we designed a portable smartphone-interfacing potentiostat with a built-in LED light source to support PEC biosensing. This device, named the PECsense was as versatile as any commercial potentiostats, having features such as adjustable recording periods, variable illumination periods, automatic data processing and being able to record both anodic and cathodic photocurrents. The PECsense was demonstrated to be used successfully as a signal reader in a PEC DNA detection assay. Ultimately, we designed several ultrasensitive PEC biosensors used for the detection of four different diagnostic biomarkers. Combined with the exploration of miniaturized design, multiplexing and portable signal-reading, our designed PEC biosensors were made PoC-capable. The work in this thesis presented innovations in areas of nanotechnology, material synthesis, solid-state physics, biotechnology and embedded systems for the advancement of biomolecular detection and PoC diagnostics. / Thesis / Doctor of Philosophy (PhD) / Biosensors show great promise for use in point-of-care diagnostics and health monitoring systems. Such deceives combine biorecongition with signal transduction for analyzing biologically relevant targets. Photoelectrochemical (PEC) mode of signal reading, particularly those based on TiO2 nanomaterials, have shown great promise in delivering point-of-care biosensors that have excellent diagnostic performance. In this thesis, our goal was to develope new techniques for creating low-cost, easy-to-use and ultrasensitive photoelectrochemical biosensors. To achieve this goal, our work here can broadly be split into three objectives. Firstly, we focused on developing new material synthesis methods to improve traditional TiO2 nanomaterials so they can be more useful in PEC biosensors. These methods involved combining TiO2 with organic molecules known as catecholates and metal nanoparticles. This work created material systems that are able to generate high signals and more easily interface with biomolecules for improving PEC biosensor sensitivity. For the second objective, we used our newly developed enhanced TiO2 nanomaterials as the foundation for designing various bioassays for the detection of a wide range of different biological targets such as DNA, RNA, proteins and bacteria. This served to demonstrate the robustness of PEC signal reading as a tool for various markers of diseases. Despite PEC biosensors being a powerful tool in healthcare, they have seen very little commercial breakthrough, which can primarily be attributed to needing bulky benchtop instruments and light sources for signal reading. For the last objective, we worked on designing a handheld smartphone-operated signal-reader for PEC biosensing with its own built-in light source.

<p dir="ltr">With climate change creating the need for renewable energy to replace fossil fuels, solar energy technologies are primed to dominate the energy sector. And while photovoltaics have improved significantly in recent decades, continued evolution of this technology requires research into new fabrication techniques and new materials. The solution processing of metal chalcogenide semiconductors offers an opportunity to fabricate photovoltaics in a low-cost and high-throughput way. However, for this methodology to make a commercial impact a variety of challenges around the fundamental chemistry and materials science need to be addressed. Furthermore, while solution processing has been applied heavily to the Cu(In,Ga)(S,Se)₂ family of materials, these techniques can also open doors for emerging materials like Cu₂ZnSnSe₄, Ag₂ZnSnSe₄, and the chalcogenide perovskites.</p><p dir="ltr">In solution processed Cu(In,Ga)(S,Se)₂ devices, researcher have generally started with a Cu(In,Ga)S₂ film that is then selenized to form the final Cu(In,Ga)(S,Se)₂ material. However, this process has been connected to the formation of a problematic “fine-grain” layer. To solve this issue, the molecular precursors from amine-thiol chemistry were modified to produce soluble molecules with metal selenium bonding. This enabled direct solution deposition of CuInSe₂ films that could be processed without forming a fine grain layer.</p><p dir="ltr">Reactive dissolution chemistry (or “alkahest” chemistry) is useful for solution processing because it can enable the direct use of metal or metal chalcogenide precursors, bypassing the potential impurities from metal salt precursors. However, the commonly used amine-thiol reactive solvent system is better suited to making metal sulfides than metal selenides because the thiol acts as a sulfur source. To address this limitation, a new alkahest based on alkylammonium polyselenide solutions was developed which could reactively dissolve a wide range of metals, metal chalcogenides, and metal oxides. This generalizable chemistry enabled the synthesis of a wide range of binary and multinary metal chalcogenides including Cu(In,Ga)Se₂, Cu₂ZnSnSe₄, and Ag₂ZnSnSe₄.</p><p dir="ltr">Emerging metal chalcogenide semiconductors composed of earth-abundant and non-toxic elements that can exhibit strong optoelectronic properties and high stability are a target of significant interest. Chalcogenide perovskites like BaZrS₃ and BaHfS₃ are an intriguing option to satisfy these requirements but have rarely been studied because of synthesis difficulties, historically being made by solid-state reactions or the sulfurization of oxides around 1000 °C. Here a solution-based approach that only requires moderate temperatures of 550-575 °C was developed utilizing a hybrid ink containing soluble metal thiolates and nanoparticulate metal hydrides.</p><p dir="ltr">The hybrid ink was an important proof of concept that chalcogenide perovskites could be synthesized at these moderate temperatures. However, it relies on complex and difficult to handle precursors. A simpler route would be to use air-stable precursors to make an oxide perovskite and subsequently sulfurize the material. However, this route has historically used excessively high temperatures. Therefore, a new sulfurization step was conceived based on thermodynamic arguments that includes both sulfur and hafnium sulfide as an oxygen sink. This redesigned sulfurization enabled the conversion of BaZrO₃ into BaZrS₃ at temperatures around 575 °C.</p><p dir="ltr">Finally, an energy systems and economic analysis was performed to consider how photovoltaics might be incorporated into agricultural lands. This work showed that when compared with traditional photovoltaics or a PV Aglectric concept, using corn for ethanol is an inefficient way to generate both food and energy from a given unit of land.</p>

In much of the literature about organic photovoltaics, the topic is framed within the current landscape of energy production and the research on these materials is cited as a possible solution to the energy crisis looming ahead. Despite being the most frequent, this is by no means the only perspective that can be offered. Indeed, the same research may also be set within the larger perspective offered by the field of functional materials. These materials are usually exploited for their particular responses to electrical, magnetic and chemical stimuli and are at the basis of many technologies fundamental to our society. The prominent position of functional materials in modern science is due to the emergence of novel technological needs that such materials have been able to satisfy thanks to their peculiar properties. These properties have been rationalised and mastered by expanding the theoretical description of the underlying physical mechanisms. This theoretical body, combined with the growth and diffusion of computational capabilities has fostered a change in the scientific paradigm underpinning the research effort. More and more, the predictive power of numerical approaches is exploited to lead the way in the exploration of the immense chemical space. The ultimate promise is to achieve the purpose-driven design of compounds thanks to which the molecular structure can be engineered before the actual synthesis to meet the demands dictated by a specific application. To fulfil this role, computational approaches need to be able to simulate the solid state properties at the most relevant time and length scales. If this can be accomplished then a reliable prediction of the performance can be achieved. The current work deals with the development and application of one such protocol, for the particular case of organic photovoltaic semiconductors. Given the specific application, the properties targeted are light absorption and charge transport. Particular effort is put in the simulation of local morphologies at scales above the molecular one to describe supramolecular organisation with sufficient resolution. In this thesis, the protocol is applied to two molecular systems employed in solar devices. Both systems have been selected on the basis of data suggesting that a detailed microscopic description of their behaviour could be highly informative about the aspects responsible for their photovoltaic performance. In particular, chapter 3 details the investigation of a small-molecule donor that has been shown in the literature to have a remarkable behaviour in absorption. While chapter 4 reports the study of a donor-acceptor dyad used as active layer in single-component solar devices with relatively high conversion efficiency. In both cases, the computational protocol has proven capable of providing a detailed microscopic description of the systems. The picture drawn has allowed to clarify the plausible mechanisms behind the observations and to rationalise these behaviours in a broader and more general theoretical framework.

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