M.Sc. (Physics) / Amorhous silicon is one of the most promising materials for large area solar cells for terestrial photovoltaic applications. Unfortunately these cells suffer from two serious problems: the efficiencies drop when laboratory processes are scaled up and the cells degrade after some exposure to sunlight. The exact causes of these two problems are still unknown. In this project some aspects of the above two problems where investigated. The drop in efficiency due to scaling up of laboratory processes can be ascribed to macroscopic inhomogeneities in the film. An investigation was done by changing the chamber geometry and gas flow pattern to establish empirical conditions to obtain films with maximum macroscopic homogeneity. It was found that a uniform electric field above the substrate was the most important factor determining the macroscopic homogeneity of the film. The hydronamic gas flow pattern was of secondary importance. Some techniques to obtain a uniform electric field has been devised. The photo-degradation was investigated by illuminating films of o-Si.H with simulated sunlight for different lenghts of time. The change in the electrical and optical properties of the intrinsic films were determined as function of total photon flux. No change in the optical properties could be detected. The effect of the photo-degradation manifests itself in a drop in the the dark conductivity and photoconductivity. The observed phenomena is explained in terms of photo-induced deep levels in the gap. The Fermi level shifts to the middle of the gap due to these defect states, causing a drop in the free carrier concentration and conductivity. These defect levels increase the absorptiom coefficient in the long wavelength region, but they also decrease the lifetime of the photo-generated carriers. The photo-induced defects were investigated with the CPM-technique. A large part of this project involved the construction and commissioning of the CPM-apparatus. It was found that the light introduced two types of defects at energies 0.5 eV and 0.75 eV below the conduction band edge. The concentration of the defects increases with illumination, but saturates after about 24 hours of illumination. The defects could almost completely be annealed at ISOaC. The photo-degradation of o-Si.H solar cells is ascribed to the reduction in the carrier lifetimes of photo-generated carriers due to recombination at these defect centers.

Orientador: Ennio Peres da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-27T02:08:03Z (GMT). No. of bitstreams: 1 Castro_RodolfoDamasiode_M.pdf: 3152478 bytes, checksum: a4e0e80e4ac1f8804a7b3aa8589139b4 (MD5) Previous issue date: 2015 / Resumo: A busca por meios de geração de energia para atender às necessidades humanas com menores impactos sociais e ambientais é constante. A geração de energia elétrica por meio de fontes renováveis na forma distribuída, ou não centralizada, é um meio ou método de minimizar tais impactos. O objetivo da pesquisa foi analisar a viabilidade econômica, frente a tarifa de energia elétrica das concessionárias locais, da utilização de sistemas de geração solar em residências brasileiras situadas nas capitais dos estados, na capital federal, Brasília e na cidade de Campinas (SP). Diferentes situações de dimensionamento foram utilizadas para dois tipos de sistemas: um sistema fotovoltaico puro, para atender toda a necessidade energética da residência, incluindo o chuveiro elétrico, e um sistema solar híbrido, composto por aquecimento solar para atender a demanda por água quente no banho em conjunto com geração fotovoltaica para atender as necessidades em equipamentos elétricos. As situações de dimensionamento utilizadas foram três, onde em cada uma o sistema fotovoltaico foi projetado para uma determinada produção de energia. Os sistemas fotovoltaico e de aquecimento solar foram dimensionados com o auxílio dos softwares PVSyst e Dimensol, respectivamente. O custo total dos sistemas foi estimado a partir de pesquisa em lojas com endereço eletrônico na rede de computadores e de orçamentos fornecidos por empresas do ramo. Determinou-se o preço final da energia elétrica convencional para todas as cidades a partir da tarifa definida pela ANEEL, do valor médio do PIS efetivo cobrado pelas concessionárias e da alíquota de ICMS que os governos estaduais recolhem. Após realizados os cálculos, chegou-se ao resultado de que somente nas cidades de Macapá (AP) e Boa Vista (RR), devido principalmente ao baixo custo das tarifas de energia elétrica, o usuário não economizaria com a instalação dos sistemas. Porém, em cidades de elevada tarifa, como Belém (PA) e Belo Horizonte (MG), o usuário pagaria cerca de R$ 0,30 por quilowatt hora consumido a menos / Abstract: The search for power generation means to meet human needs with lower social and environmental impacts is constant. The distributed generation of electricity by renewable energies is a method to minimize those impacts. The research aimed to analyze the economic viability against local electricity tariff of the use of solar power generation systems in Brazilian households located in the capitals of the states, in the federal capital, Brasilia, and in the city of Campinas (SP) Different sizing situations were used for two types of systems: a pure PV system to meet all the energy needs of the residence, including electric shower, and a hybrid solar system, consisting of solar heating to meet the demand for hot water in the bath together with photovoltaic generation to meet the needs in electrical equipment. Sizing situations used were three, where in each one the PV system is designed for a certain production of energy. The photovoltaic systems and solar heating were sized with the help of the softwares PVSyst and Dimensol, respectively. The total cost of the systems was estimated by a research in webstores and budgets provided by companies in the field. Was determined the final price of conventional electricity to all cities from the tariff set by ANEEL, the average value of the effective PIS charged by concessionaires and ICMS aliquot that state governments collect. After performing the calculations, came to the result that only the cities of Macapa (AP) and Boa Vista (RR), mainly due to the low cost of electricity tariffs, the user does not save due to the installation of the systems. However, in cities of high tariff, as Belém (PA) and Belo Horizonte (MG), the user would save about R$ 0.30 per quilowatt-hour / Mestrado / Planejamento de Sistemas Energeticos / Mestre em Planejamento de Sistemas Energéticos

With the progression towards lighter but larger-display self-sustainable mobile devices, device efficiency becomes increasingly important, owing to the higher power display consumption but at the same time more limitation on the size and volume of energy storage. In this thesis, selected aspects regarding to efficiency of three types of optoelectronic devices, indoor photovoltaics (IPVs), perovskite thin-film transistors (TFTs) and organic light-emitting diodes (OLEDs) have been investigated. IPVs can make off-grid devices self-sustainable by harvesting ambient light energy. Its weak irradiance necessitates high-efficiency IPVs to generate sufficient power. Our work addresses the need of knowing the limit of the device parameters for correct evaluation and understanding the efficiency loss for developing clinical tactics. We delivered a general scheme for evaluating the limiting efficiency and the corresponding device parameters of IPVs under various lights, illuminance and material bandgap. In contrast to the AM1.5G conditions, a maximum power conversion efficiency (PCE) of 51-57 % can be achieved under the optimal bandgap of 1.82-1.96 eV. We also propose using the second thickness peak of interference instead of the first as a better optimal absorber thickness after identifying the finite absorption as the major source of efficiency loss. The work provides insights for device evaluation and material design for efficient IPV devices. The novel hybrid organic-inorganic perovskites have gained enormous research interest for its various excellent optoelectronic properties such as high mobility. TFT as an alternative application to the majorly focused photovoltaics is realized in this work. There are few reports on perovskite TFTs due to wetting issues. By employing polymethacrylates with ester groups and aromatic substituents which provide polar and cation-π interactions with the Pb2+ ions, quality films could be fabricated with large crystals and high electron mobility in TFTs. We further improved the performance by resolving interfacial mixing between the perovskite and the polymer using the crosslinkable SU-8, achieving the highest mobility of 1.05 cm2 V−1 s−1. Subsequently, we cured the grain boundaries using methylamine solvent vapor annealing, suppressing the TFT subthreshold swing. The work provides a map for the improvement of perovskite TFTs. It has been revealed that molecular orientations of the emitters in OLEDs with the transition dipole moment lying in plane enhances light outcoupling efficiency. Multiple experimental techniques are needed to provide complementary orientation information and their physical origin. Here, we propose using TFT to probe the orientation of the phosphorescent emitters. Homoleptic fac-Ir(ppy)3 and heteroleptic trans-Ir(ppy)2(acac) and trans-Ir(ppy)2(tmd) were deposited on polystyrene (PS) and SiO2 substrates. Compared to the PS surface inducing isotropic orientation as the control, trans-Ir(ppy)2(acac) and trans-Ir(ppy)2(tmd) possessed decreased carrier mobilities on SiO2. With the study of initial film growth, we infer that preferred orientation induced by the polar SiO2 surface led to an increase in energetic disorder in the well-stacked trans-Ir(ppy)2(acac) and hopping distance in the amorphous trans-Ir(ppy)2(tmd). The highly symmetric fac-Ir(ppy)3 remained its isotropic orientation despite the dipolar interaction. Surprisingly, the TFT technique gives much higher sensitivity to surface-induced orientation, and thus may potentially serve as a unique electrical probe for molecular orientation.

With the progression towards lighter but larger-display self-sustainable mobile devices, device efficiency becomes increasingly important, owing to the higher power display consumption but at the same time more limitation on the size and volume of energy storage. In this thesis, selected aspects regarding to efficiency of three types of optoelectronic devices, indoor photovoltaics (IPVs), perovskite thin-film transistors (TFTs) and organic light-emitting diodes (OLEDs) have been investigated. IPVs can make off-grid devices self-sustainable by harvesting ambient light energy. Its weak irradiance necessitates high-efficiency IPVs to generate sufficient power. Our work addresses the need of knowing the limit of the device parameters for correct evaluation and understanding the efficiency loss for developing clinical tactics. We delivered a general scheme for evaluating the limiting efficiency and the corresponding device parameters of IPVs under various lights, illuminance and material bandgap. In contrast to the AM1.5G conditions, a maximum power conversion efficiency (PCE) of 51-57 % can be achieved under the optimal bandgap of 1.82-1.96 eV. We also propose using the second thickness peak of interference instead of the first as a better optimal absorber thickness after identifying the finite absorption as the major source of efficiency loss. The work provides insights for device evaluation and material design for efficient IPV devices. The novel hybrid organic-inorganic perovskites have gained enormous research interest for its various excellent optoelectronic properties such as high mobility. TFT as an alternative application to the majorly focused photovoltaics is realized in this work. There are few reports on perovskite TFTs due to wetting issues. By employing polymethacrylates with ester groups and aromatic substituents which provide polar and cation-π interactions with the Pb2+ ions, quality films could be fabricated with large crystals and high electron mobility in TFTs. We further improved the performance by resolving interfacial mixing between the perovskite and the polymer using the crosslinkable SU-8, achieving the highest mobility of 1.05 cm2 V−1 s−1. Subsequently, we cured the grain boundaries using methylamine solvent vapor annealing, suppressing the TFT subthreshold swing. The work provides a map for the improvement of perovskite TFTs. It has been revealed that molecular orientations of the emitters in OLEDs with the transition dipole moment lying in plane enhances light outcoupling efficiency. Multiple experimental techniques are needed to provide complementary orientation information and their physical origin. Here, we propose using TFT to probe the orientation of the phosphorescent emitters. Homoleptic fac-Ir(ppy)3 and heteroleptic trans-Ir(ppy)2(acac) and trans-Ir(ppy)2(tmd) were deposited on polystyrene (PS) and SiO2 substrates. Compared to the PS surface inducing isotropic orientation as the control, trans-Ir(ppy)2(acac) and trans-Ir(ppy)2(tmd) possessed decreased carrier mobilities on SiO2. With the study of initial film growth, we infer that preferred orientation induced by the polar SiO2 surface led to an increase in energetic disorder in the well-stacked trans-Ir(ppy)2(acac) and hopping distance in the amorphous trans-Ir(ppy)2(tmd). The highly symmetric fac-Ir(ppy)3 remained its isotropic orientation despite the dipolar interaction. Surprisingly, the TFT technique gives much higher sensitivity to surface-induced orientation, and thus may potentially serve as a unique electrical probe for molecular orientation.

A research report submitted in partial fulfilment to the degree of Master of Science in the School of Physics, University of the Witwatersrand, 2018 / With the global energy consumption at an all-time high and the demand for energy estimated to triple by 2050, renewable energy sources such as solar are pivotal in an addressing this global energy demand. Solar power generation by photovoltaic cells enjoys several advantages compared to other forms of electricity generation such as a reduced fossil fuel dependence, modularity, easy and flexible installation, and scalability. The development of novel solar cells that offer increased efficiencies is an integral component of the process of addressing the global energy needs. Solar cell device simulations offer a cost-effective means to explore the impact of different material properties on the overall efficiency of the solar cell. The use of ab initio calculated material properties that serve as an import for the device simulations offers a means to easily study and estimate the typical solar cell efficiencies of different types of solar cells. The implementation of new light harnessing features, like frequency conversion layers or plasmonic nanoparticles, and the integration of these futures into existing device simulation codes serves as a useful tool that aids solar cell development. This work explores the theoretical and numerical background for the simulation of solar cell devices. A brief explanation of how ab initio calculated parameters can be used, together with the implementation of frequency conversion techniques in existing simulation codes is given. It is shown that the solar cell performance parameters can be well approximated using ab intio parameters. Also, the positive effect of frequency conversion techniques is demonstrated with examples of how this tool can be implemented in existing solar cell device simulation codes. The approaches discussed in this work can serve as a good framework for the modeling of novel solar cell devices / MT 2019

No description available.

This dissertation introduces a new planning and operational tool to integrate photovoltaic (PV) systems into the utility's generation mix. It is recognized that much of the existing research concentrated on the central PV system, its operations, and long-term planning with PV system and concluded that technical problems in PV_ operation. will _power was subtracted from the utility load with the expectation that conventional generation would meet the load. This approach is valid for small penetration levels and for PV facilities connected near the load centers. Second, PV system was studied on a case-by-case basis. This made the interactions between the PV systems and conventional power systems not well known to the operator in the dispatch center on one hand, and to the PV system manufacturer, on the other hand. In addition, several constraints such as thermal generation ramping capabilities, energy costs, tie-line interchange, spinning reserve requirements, hydro availability and generating capacity, and pumped-storage scheduling are not adequately represented in this process. These are real problems and their solutions are sought in this dissertation. Finally, the value of PV systems does not lie only in serving load, but also in reducing problems associated with emissions. It is felt that a comprehensive methodology that would take into account the PV system characteristics and the forth mentioned constraints, as well as more global penetration is developed. The proposed methodology is designed to handle load dynamics and PV fluctuations, so as to minimize operational problems. The objective of this study is to determine the economic and operational impacts when large photovoltaic systems are incorporated into the electric utility generation mix. The proposed methodology handles combustion turbines, hydro and pumped-storage hydro power systems. Performance analysis shows that hydro availability, generation mix and characteristics, PV power output dynamics and performance, time of the year, and energy costs influence the economic and operational impacts of large-scale PV generation. Results show that while hydro dispatching increases acceptable PV penetration levels, generation mix and energy costs influence the breakeven capital cost. According to this study, for a 10 percent PV penetration level (1200 MW) and high energy costs, the breakeven capital cost is $968/kW and $1200/kW for Richmond (Virginia) and Raleigh (North Carolina), respectively. This corresponds to an energy cost of 3.20 and 3.00 ¢/kWh for Richmond and Raleigh. / Ph. D.

Thesis (MPhil (Public Management and Planning))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The thesis examines whether a residential solar power system (comprising a solar photovoltaic [PV] system and a solar water heater [SWH]), a demand-side option, has a lower life-cycle cost than a coal-fired power plant, a supply-side option, or vice versa. It also investigates whether a million residential solar power systems could potentially replace a 4 800 MW coal-fired power plant in South Africa. The study also explores, should a million solar power systems be installed on residential units, what the total energy output, the equivalent in coal-fired generation capacity, and the comparative costs of the two power systems would be. The common belief is that solar PV technology is unviable for electricity production because it is too expensive compared to coal-based electricity. Statements such as these are made because the initial capital costs (procurement costs) are often used as the primary (and sometimes only) criterion for project, equipment or system selection based on a simple payback period. Due to life-cycle stages, often the real costs of the project or equipment are not reflected by the upfront capital costs. In this thesis, a methodology is developed to investigate the life-cycle cost effectiveness of a residential solar power system (comprising a 5 kW PV roof tile system and a 300 litre SWH) and a 4 800 MW coal-fired plant in order to choose the most cost effective alternative in terms of the project‟s functional unit (kWh). A 5 kW solar PV roof tile system and a 300 litre SWH system have been installed at Lynedoch Eco-village. The operational results from this experiment was used as a basis for developing a model for a million residential rooftops that will have a 5 kW PV roof tile system plus a 300 litre SWH system. The focus of the million rooftops model is operating costs over the lifetime of the solar power system, on the assumption that the capital costs will be financed from coal-fired generation capacity that will no longer be needed. The results of the study indicate that a residential solar power system is most cost effective over a 40-year life-cycle period in terms of the project‟s functional unit (kWh). The thesis also finds that a million residential solar power systems (comprising a 5 kW PV system and a 300 litre SWH) could potentially replace 40% of a 4 800 MW coal-fired generation capacity. In total, 2.3 million residential solar power systems are needed to replace a 4 800 MW coal-fired generation capacity. Emissions of 37 million tonnes of CO2 equivalent per year could be avoided if 2.3 million residential solar power systems were to be installed. However, the investment needed to install Lynedoch solar power systems (comprising a 5 kW PV roof tile system and a 300 litre SWH) on 2.3 million residential rooftops is fifteen times more than the investment needed to build a 4 800 MW coal-fired power plant. The investment needed to install 2.3 million Lomold residential solar power systems (comprising a 5 kW Lomold PV roof tile system and a 300 litre SWH) is six and half times more than the investment needed for a 4 800 MW coal-fired power plant. It was established during the study that if Lynedoch residential solar power systems were to be installed on the roofs of a million South African households, 152 308 jobs would be created in the manufacturing and installation supply chain. For the 2.3 million Lynedoch residential solar power systems needed to replace an entire 4 800 MW of coal-fired generation capacity, 340 690 jobs would be created in the manufacturing and installation supply chain. Installation of a million Lomold residential solar power systems would create 63 929 jobs in the supply chain. Installation of 2.3 million Lomold residential solar power systems would essentially create 147 298 jobs. / AFRIKAANSE OPSOMMING: Die tesis stel ondersoek in na die vraag of ʼn residensiële sonkragstelsel (bestaande uit ʼn fotovoltaïese (FV) stelsel en ʼn sonwaterverhitter [SWV]), ʼn vraagkant-opsie, ʼn laer lewensikluskoste as ʼn steenkoolkragsentrale, ʼn aanbodkant-opsie, het of omgekeerd. Daar word ook ondersoek of ʼn miljoen residensiële sonkragstelsels potensieel ʼn 4 800 MW-steenkoolkragsentrale in Suid-Afrika kan vervang. Verder word daar ondersoek, indien ʼn miljoen sonkragstelsels op residensiële eenhede aangebring word, wat die totale energie-uitset, die gelykstaande uitset van steenkool-opwekkingskapasiteit en die vergelykende koste van die twee kragstelsels sal wees. Die algemene oortuiging is dat sonkrag- FV tegnologie ongeskik is vir elektrisiteitsopwekking omdat dit te duur is in vergelyking met steenkoolgebaseerde elektrisiteit. Sodanige stellings word gemaak omdat die aanvanklike kapitaalkoste (aankoopkoste), gegrond op ʼn eenvoudige terugbetalingstydperk, dikwels as die primêre (en soms selfs die enigste) maatstaf tydens die keuse van ʼn projek, toerusting of stelsel dien. Die werklike kostes van ʼn projek of toerusting word egter dikwels nie in kapitaalkostes weerspieël nie, omdat hierdie maatstaf nie totale lewensikluskoste in ag neem nie. In hierdie tesis word ʼn metodologie ontwikkel om die lewensiklus-kostedoeltreffendheid van ʼn residensiële stelsel (bestaande uit ʼn 5 kW FV-dakteëlstelsel en ʼn 300 liter-SWV) en ʼn 4 800 MW-steenkoolkragsentrale te bereken sodat die kostedoeltreffendste opsie in terme van die projek se funksionele eenheid (kWh) gekies kan word. ʼn Residensiële sonkragstelsel bestaande uit ʼn 5 kW FV-dakteëlstelsel en ʼn 300 liter-SWV is in Lynedoch Eco-village geïnstalleer. Die operasionele resultate van die eksperiment is gebruik as grondslag vir die ontwikkeling van ʼn model vir die installering van ʼn 5 kW sonkrag-FV-dakteëlstelsel en ʼn 300 liter-SWV op ʼn miljoen residensiële dakke. Die fokus van die hierdie model is die operasionele koste oor die leeftyd van die sonkragstelsel, gegrond op die aanname dat die kapitaalkoste gefinansier sal word deur fondse wat nie meer vir die oprig van steenkoolkragsentrales benodig word nie. Die tesis se bevindinge dui daarop dat ʼn residensiële sonkragstelsel die kostedoeltreffendste is oor ʼn lewensiklustydperk van 40 jaar in terme van die projek se funksionele eenheid (kWh). Daar is ook gevind dat ʼn miljoen residensiële sonkragstelsels (bestaande uit ʼn 5 kW FV-dakteëlstelsel en ʼn 300 liter-SWV) potensieel 40% van ʼn 4 800 MW-steenkoolkragsentrale se kapasiteit kan vervang. Altesaam 2.3 miljoen residensiële sonkragstelsels is nodig om die kapasitiet van ʼn 4 800 MW-steenkoolkragsentrale ten volle te vervang. Gasvrystelling van 37 miljoen ton CO2-ekwivalent per jaar kan vermy word as 2.3 miljoen residensiële sonkragstelsels geïnstalleer word. Die belegging wat benodig word om Lynedoch-sonkragstelsels (bestaande uit ʼn 5 kW FV-dakteëlstelsel en ʼn 300 liter-SWV) op 2.3 miljoen residensiële dakke te installeer, is egter vyftien keer groter as die belegging wat benodig word om ʼn 4 800 MW-steenkoolkragsentrale te bou. Die belegging wat benodig word om Lomold- residensiële sonkragstelsels (bestaande uit ʼn 5 kW Lomold-FV-dakteëlstelsel en ʼn 300 liter-SWV) te installeer, is ses en ʼn half keer groter as die belegging wat nodig is om ʼn 4 800 MW-steenkoolkragsentrale op te rig. Die studie het bepaal dat as Lynedoch- residensiële sonkragstelsels op die dakke van ʼn miljoen Suid-Afrikaanse huishoudings geïnstalleer word, 152 308 werksgeleenthede in die vervaardigings- en installeringsaanbodketting geskep sal word. Met die 2.3 miljoen Lynedoch- residensiële sonkragstelsels wat benodig word om ʼn 4 800 MW-steenkoolkragsentrale te vervang, sal 340 690 werksgeleenthede in die vervaardigings- en installeringsaanbodketting geskep word. Die installering van ʼn miljoen Lomold- residensiële sonkragstelsels sal 63 929 werksgeleenthede in die voorsieningsketting skep, terwyl die installering van 2.3 miljoen Lomold- residensiële sonkragstelsels 147 298 werksgeleenthede sal skep. / Centre for Renewable and Sustainable Energy Studies

Thesis (MBA)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Many rural areas in Africa still lack adequate electricity supply. This has been identified as a major obstacle to development in many African nations. The high costs associated with providing electricity through national grid systems prevent many governments from delivering electricity to remote rural areas. The purpose of this study is to define a strategic architecture and business model that can be used to provide solar energy to Small, Medium and Micro Enterprises (SMMEs) in Africa. The desired outcome is a sustainable business model for solar energy provision that can be implemented in the African context. This study uses the strategic architecture framework developed by Ungerer, Pretorius and Herholdt (2011) to achieve this. Primary data was collected through interviews with industry experts and this was supplemented with a comprehensive review of current literature. An analysis of the PV market shows that solar PV has grown significantly over the past decade and the industry is already extremely competitive. The highest competitive pressures include substitute products, high buyer bargaining because of low product differentiation, and the threat of new entrants. The industry has a clearly defined value chain starting with the manufacturing of PV panels and other systems components, but goes as far as providing financing to customers. The profit potential in the industrial and commercial segments is highest and key competitors in this segment offer similar products and services. The customer analysis showed that small businesses vary considerably in the products and services they offer and that their energy needs also differ. Services that can be offered to these customers include energy efficiency assessments, system design, pre-project services, financing, system installation and system monitoring, operation and maintenance. The organisation that will implement the strategy is a company called Solshare. The organisation identified its vision and mission, and core values and defined the domain it will participate in. The commercial and industrial segments are regarded as the most appealing segments and the core product offering is energy efficiency assessments and solar installations. This will be offered through an innovative shared-solar model that also includes system financing, system monitoring and system optimisation, and will be implemented by carefully selected partners to minimise cost. Solshare’s objective is to develop a distinctive competence in financing and implementing shared-solar projects through strategic partnerships, while providing excellent customer service. It will employ is a focused low-cost strategy by providing solar energy to small businesses at the lowest cost possible, through a shared resource approach. Costs will be managed by focusing on a core set of activities and outsourcing non-core activities. The key value proposition is the development, installation and servicing of quality shared-solar solutions at the lowest cost. The cost drivers include the costs of solar system components procured from suppliers, the installation costs, salaries, marketing costs, system maintenance, and legal fees to draw up contracts and lease agreements. Income streams include energy assessments, fees charged for site selection and procurement, the installation of systems, and the monitoring and maintenance of installed systems. The capital mix consists of 30% equity and 70% debt and organisation aims to optimise resource velocity through completing new installations within a four month period and by employing a core team of professional sales and technical staff, while outsourcing non-core processes.

This thesis improves our understanding of the charge-transfer dynamics in organic materials employed in dye-sensitized and nanotube-thiophene solar cells. For the purpose of this work, a femtosecond transient absorption spectroscopy setup was built. Additionally, microsecond transient absorption spectroscopy was utilised to explore dynamics on a longer time-scale. In the first study, the dependence of dye regeneration and charge collection on the pore- filling fraction (PFF) in solid-state dye-sensitized solar cells (DSSCs) is investigated. It is shown that while complete hole transfer with PFFs as low as ~30% can be achieved, improvements beyond this PFF are assigned to a stepwise increase in the charge-collection efficiency in agreement with percolation theory. It is further predicted that the chargecollection efficiency saturates at a PFF of ~82%. The study is followed by an investigation of three novel hole-transporting materials for DSSCs with slightly varying HOMO levels to systematically explore the possibility of reducing the loss-in-potential and thus improving the device efficiency. It is shown that despite one new HTM showing a 100% hole-transfer yield, all devices based on the new HTMs performed worse than those incorporating spiro-OMeTAD. Furthermore, it is demonstrated that the design of the HTM has an additional impact on the electronic density of states present at the TiO₂ electrode surface, and hence influences not only hole- but also electron-transfer from the sensitizer. Finally, a study on a polymer-single-walled carbon nanotube (SWNT) molecular junction is presented. Results from femtosecond spectroscopic techniques show that the polymer poly(3-hexylthiophene) (P3HT) is able to transfer charges to the SWNT within 430 fs. Addition of excess P3HT polymer leads to long-lived free charges making these materials a viable option for solar cells.