Hybrid PV-wind systems improve land use efficiency but introduce shading interactions, with wind turbines potentially reducing PV output. The PVMD Toolbox is an energy yield simulation tool that accounts for a PV module’s position, mounting, and surroundings, enabling detailed shading analysis. However, high accuracy in modeling how the module perceives its environment comes at significant computational cost. A selective skydome refinement method was developed and implemented in the PVMD Toolbox to perform accurate and efficient shading analysis for PV modules in complex environments. The method begins with a coarse-resolution skydome simulation to identify shaded regions, which are then selectively refined, along with a surrounding buffer. Sensitivity values are recalculated only for the refined areas using targeted ray tracing, while the rest retain values from the initial simulation. This approach reduces ray tracing operations by over 70% and total simulation time by approximately 90%, with a relative DC energy yield error of less than 1%. The method was validated across different initial resolutions, demonstrating a consistent trade-off between computational efficiency and accuracy. In large-scale PV-wind layouts, it captured spatial shading effects reliably and highlighted the importance of fine-resolution input data.

Due to increasing population growth and industrialization, the energy demand is soaring around the world. In order to meet this energy demand and continuing with business as usual, there is an increased need for fossil fuels. Burning of fossil fuels such as coal, gas and oil lead to emission of carbon dioxide in atmosphere. Emission of carbon dioxide rises the earth’s surface temperature and is leading to global warming. In order to tackle this crisis, an alternative to fossil fuels need to be investigated. In this regard, renewable energy sources are key as they can be replenished. Solar energy is one of the fastest growing and promising renewable energy sources.

Photovoltaics (PV) modules or solar panels have been installed across the world, converting solar energy into electrical energy. The PV market is dominated by single junction crystalline silicon (c-Si) solar cells. In order to improve the efficiency of single junction solar cells beyond their efficiency limit, tandemsolar cells, which stack one solar cell on top of another, are being actively explored by researchers. In this work, we have focused on perovskite/c-Si tandem solar cells.

Since direct contact of metal with semiconductor leads to recombination, the concept of carrier-selective passivating contacts (CSPCs), which separates the absorber from the metal by a thin passivating layer, becomes important. The most common type of CSPCs are doped hydrogenated amorphous silicon (a-Si:H) on intrinsic amorphous silicon, as in the case of silicon heterojunction (SHJ) solar cells. The other type of CSPCs are polycrystalline silicon (poly-Si) on ultrathin silicon oxide (SiOx) as in the case of poly-Si solar cells. Depending on the fabrication temperature of CSPCs, the former comes under low temperature CSPCs while the latter is a type of high temperature CSPCs. While low temperature CSPCs have been successfully integrated in perovskite/c-Si tandem solar cells, research involving high temperature CSPCs is less developed. In this work, high temperature CSPCs are studied, optimized and integrated in perovskite/c-Si tandem solar cells. In addition, the performance of tandem solar cells is evaluated not only in terms of efficiency but also energy yield which is more relevant for outdoor environment. In addition to poly-Si, this work explores novel materials such as polycrystalline silicon oxide (poly-SiOx) and polycrystalline silicon carbide (poly- SiCx) as high temperature CSPCs...

As the global community seeks to improve current energy technologies for a sustainable future, offshore PV systems show great potential to overcome the land use limitations of traditional PV systems. There is a complex interaction between different environmental forces at sea with the PV structure. Empirical studies on these environmental interactions can provide critical insights to optimize the design of offshore PV systems. This thesis has identified a gap in wind loading studies on offshore PV designs. The primary objective of this research is to develop a methodological approach for studying the wind-induced tilt variations in floating PV (FPV) systems, with the intent of informing future PV performance assessment frameworks. A numerical modelling approach using the CFD tool ANSYS Fluent is adopted as the base methodology. The first phase of the study employs single-phase wind tunnel models in 2D and 3D to study flow behaviour over the required geometry. The models are validated against literature and used as the basis to construct a multi-phase model to simulate wind flow over a floating body and how it moves in response to the water surface.

The model is used to perform sensitivity studies on wind speed, module orientation, module tilt, and floater height. The simulation results indicate that tilt variations induced by wind flow are minimal, under 5◦, for still water conditions. In addition, it also suggests an increase in wind velocity increases the non-linearity in the rotational response of the body, changes in the direction of rotation depending on the speed of the flow and tilt of the module, and a sharp increase in rotation with an increase in floater height. The highest rotational response of 4.07◦(anticlockwise) was observed for a design tilt of 24◦ and a wind speed of 40 m/s.

Based on the simulation results, a PV yield assessment is done, and it is found that the inclusion of tilt effects changes the yield by less than 0.5%. Given the high computational cost involved, a numerical approach for wind load evaluation is not justified in terms of yield variation. For future work, it is recommended to first conduct experimental studies to verify the effects of wind loading on different FPV system designs. This could be supplemented with numerical approaches in the future using high-performance computational resources.

Interest in incorporating renewable energy systems into current infrastructure has surged as a result of the growing need for sustainable energy solutions in urban settings. This thesis investigates the optimization of a heating and cooling system designed for residential and commercial buildings, with a focus on Dutch climate conditions. The system consists of photovoltaic thermal (PVT) collectors, aquifer thermal energy storage (ATES), heat exchanger and heat pumps. By using these technologies, buildings will be able to satisfy energy demand sustainably without the need for fossil fuels.

Through dynamic simulations, the research aims to optimize the energy system's performance while taking into account a range of operational scenarios and parameter values. Critical components, including the ATES and PVT collectors, are modeled to evaluate their working and performance with heat pumps to provide heating and with heat exchanger for cooling.

The Photovoltaic Materials and Devices research group at TU Delft uses the PVMD Toolbox, a sophisticated modeling tool. Few models from the toolbox are utilised in developing an integrated model, which is later implemented in the toolbox. Later on, it is optimized to improve its effectiveness through dynamic sizing of collectors and aquifers, and implementation of operational modes, making overall the integrated system more robust and redundant. The performance of the integrated system is then studied for a base scenario with 10 PVT collectors and 27,000 m^3 aquifer volume for the current scenario. It showcases promising results. To assess its applicability, the system is analysed under various scenarios. The first scenario is a season-wise performance assessment, where it is showcased that PVT produce energy during summer months and the rest of the year there is a consistent performance by ATES. On comparing the performance of different insulation levels of the buildings, it is found that the future scenarios require half or one-fourth of the energy as compared to the current scenario and the system performs better for them in terms of power consumption by heat pumps. The system's performance under different flow rates of water from PVT and ST is assessed. It is found that at a higher flow rate, a higher amount of energy is generated by both of the collectors, while ST shows better performance than PVT.

For the case when the system provides underfloor heating, it shows that the heat pumps require almost 25% of the energy required for radiator heating. The integrated system is then compared to that of conventional energy systems, demonstrating similar costs but almost no environmental impact and better energy efficiency.

The research findings present a compelling argument for the implementation of such energy systems in urban environments, as they indicate the possibility of substantial energy savings and a decrease in carbon emissions. The report also offers suggestions for future work, such as the application of advanced software, location feasibility studies, and various ATES to precisely model and scale such systems in various real-world circumstances.

This thesis contributes significant insights into the subject of renewable energy systems and lays the groundwork for further study and development of sustainable heat networks by offering a thorough analysis of an innovative method of sustainable energy management.

The transition to renewable energy sources is essential to mitigate the impacts of climate change, with solar energy playing a pivotal role in this shift. Photovoltaic (PV) technology. However, the traditional single-junction cells are reaching their theoretical efficiency, which currently stands at 29.43%. Through the use of tandem solar cells, this efficiency limit can be surpassed. The tandem cell is being researched further to increase the power conversion efficiency (PCE). However, the conventional two-terminal (2T) and four-terminal (4T) tandem configurations face challenges related to current matching and optical losses, respectively.
This project addresses these challenges by focusing on the development and optimization of a three-terminal (3T) perovskite/silicon tandem module. The research aims to enhance the energy yield of 3T module under real-world conditions by developing a comprehensive 3T model within the Photovoltaic Material and Devices (PVMD) Toolbox, bridging the gap between cell-level and module-level optimization, which has been underexplored in existing studies.
The first step involved the development of the 3T model, which incorporates independent connections for each sub-cell and utilizes an interdigitated back contact (IBC) on the bottom cell as the third terminal. The 3T model is developed and simulated in MATLAB to be validated, showing close alignment of IV curves compared to the existing literature. The 3T model is then used to simulate a 72-cell module to be validated with a widely used electrical simulator called LTspice. The validation of the developed MATLAB 3T model against LTSpice simulations demonstrated a close match, with an RMSE result of 0.02% errors, confirming the model's accuracy in predicting the IV curves and energy yield for various operating conditions.
The second phase of the research involved detailed comparisons between the performances of 2T and 3T modules, each consisting of 72 cells, under both standard test conditions (STC) and real-world conditions in Delft as a sample. The simulations revealed that the 3T module provides less annual energy yield than 2T. However, the 3T module performs better than 2T at handling spectral irradiance variations and current mismatch situations under real-world conditions. At a certain hour, 3T outperforms 2T by yielding 220.75 W compared to 219.1 W. The loss analysis confirms that the 3T module produces less mismatch loss under real conditions than the 2T module. The simulations at four different locations also show that 3T has a certain number of times when 3T yields more energy than 2T. This shows the potential of 3T to outperform 2T by optimizing the perovskite bandgap energy and thickness.
The optimization of the 3T module focused on adjusting the perovskite layer's bandgap energy and thickness. The optimal bandgap energy is identified as 1.64 eV, and the ideal thickness is 600 nm for 2T, yielding 588.79 kWh. On the other hand, 3T has optimal perovskite bandgap energy and thickness of 1.82 eV and 600 nm, respectively, yielding lower energy of 583.24 kWh. Then, the modules are expanded into 144-cell modules, which results in 3T consistently yielding around 0.4% to 0.8% more energy at its optimum perovskite bandgap energy and thickness at 4 location samples compared to the 2T. For example, at Delft, the 3T yields more annual energy of 1172 kWh than 2T of 1167 kWh. This is due to the reduced end loss produced by 3T at a larger number of cells in the module. These results show that the 3T outperforms 2T at its respective optimum perovskite bandgap energy and thickness at every location sample and at a larger number of cell modules. Although the current 3T technology with IBC is still expensive, it is expected to become competitively priced in the future. These findings highlight the importance of ongoing optimization and development of 3T modules to fully unlock their potential in various environmental conditions.

As the energy demand keeps rising and the need for clean, affordable energy increases, the switch to completely sustainable energy production comes closer and closer. Solar cells are expected to play a big role in this energy transition. However, the technology of the most used type of solar cell, crystalline silicon, is nearing its limit. This calls for other novel technologies that could surpass it. One of these promising technologies is the perovskite / c-Si tandem cell. This type of cell has shown promising results in recent years, but for it to be commercialized and challenge the current technologies that dominate the market, some steps need to be taken. This thesis focuses on hysteresis, a behaviour commonly shown in perovskite cells, resulting in an uncertainty when measuring the characteristics of these cells. The most common explanation for this behaviour has been due to ion migration under certain conditions. This report, however, looks at hysteresis from a different perspective. It investigates the effect of defects on the hysteresis behaviour, continuing on previous research on this mechanism. It is argued that the defects trap charge near the interfaces, affecting the charge extraction and with that the amount of recombination in the cell. This hypothesis is researched by modelling a state-of-the-art perovskite / c-Si tandem cell in TCAD Sentaurus. This research investigates multiple important parameters to these defects, such as defect density, distribution, energy level, and capture cross-section. With these variables, the hysteresis behaviour as a result of the defects is explored. These results are then used to compare the hysteresis behaviour of the tandem cell with a similar single-junction cell, after which the difference between the two is analysed. It is found the two types of cells have similar hysteresis behaviours, but not equal. With the main deviation finding its origin in the current-limiting that can be displayed by tandem cells.

Photovoltaic-Thermal (PVT) modules, alongside Solar Thermal (ST) and Photovoltaic (PV) technologies, offer solutions to energy demands such as electrical consumption, space heating, and domestic hot water of residential buildings. This research employs a model-based approach to analyze how building insulation, solar collector configurations, and seasonal heating modes impact system design. Enhanced insulation scenarios demonstrate potential space heating demand reductions up to 70\%, highlighting the relevance of proper insulation selection.
The findings identify that using a PVT/PV configuration with one module per string is optimal, reducing roof area usage while achieving balanced thermal and electrical energy exchange. The analysis further reveals that higher indoor temperature settings substantially increase heating demands, suggesting significant energy savings potential through temperature set point adjustments. Operational heat supply strategies are adapted to seasonal variations, optimizing the use of solar energy and effectively incorporating aquifer thermal energy storage (ATES) systems as seasonal storage for winter months. But notably, the integration of PVT modules with heat pumps emerged as the primary driver of heat supply, contributing approximately 67\% of the total heat demand.

Throughout the development of crystalline-silicon/perovskite tandem solar cells, the degradation rate of the perovskite top cells has become a limiting parameter. Currently, perovskite faces stability issues, mainly caused by corrosion and the light-soaking effect. This work investigates the degradation rate of the perovskite top cell, where a model is created to determine the parameters from the single diode model that change the IV-curve of a solar cell and lifetime energy yield simulations were performed to find the maximum tolerable degradation rate of perovskite in a tandem module to obtain a higher energy yield compared to a single-junction module Using experimental data from the King Abdullah University of Science and Technology (KAUST), where the external parameters from the measurements were provided, the changes over time in the ideality factor, saturation current, shunt resistance, and series resistance were estimated, using a numerical model. Linear trend lines through the fitting parameters over time were used and lifetime energy yield simulations were performed. For these simulations, a crystalline-silicon/perovskite tandem cell with an efficiency of 31.1% was compared to to a single-junction cell with an efficiency of 23.9%, where the single-junction cell’s optics are the same as the tandem cell’s bottom cell. To perform lifetime energy yield simulations, the PVMD toolbox is used.
Simulating the lifetime energy yield over 10 years, a perovskite degradation rate of 27.5%/year was found using the electrical parameters under STC, where the power output decreased from 4.95W to 0.24W per cell. Comparing 2T and 4T configurations, where the cell optics were kept the same, degradation rates of 21.2%/year and 9.5%/year were found for 2T and 4T, respectively. Looking at different geographical locations, degradation rates of 19%, 20%, 20.6% and 21.2% per year were found for Delft, Lagos, Lisbon and Shanghai, respectively. These differences were caused by current mismatch between the top and bottom cell, where the highest mismatch of 0.55 mA/cm2 was found in Shanghai.
To determine the maximum tolerable degradation rate of the perovskite top cell resulting in a higher lifetime energy yield for a tandem module compared to a single-junction module over 25 years, various degradation rates were analyzed. The perovskite degradation rate must be lower than 1.5%/year and 3.1%/year for 2T and 4T configurations, respectively, assuming no degradation in the silicon single-junction cell and the tandem cell’s bottom cell.

Coolworld Waalwijk, a cooling machines rental service experiences marginal growth due to the rise of cooling systems for temporarily use. Their testing facility is heavily occupied for testing systems up to 800 kW. Besides the willingness to more sustainable practices, the urge rises for implementation of new energy solutions to their 500 MWh annual consumption for both heat and electrical demand.

Currently, investments in solar-generated energy have become cheaper than fossil fuel alternatives and the rise of newly developed technology such as PVT panels is ever-increasing. This is especially relevant when considering the PV energy generation losses that occur when exposed to high temperatures. This is where Coolworld comes in. In seeking a sustainable alternative energy resource, their residual cold could actively cool solar panels, enhancing their performance.

This master's thesis aims to gain insight into the energy-intensive processes and losses at Coolworld Waalwijk's testing facility and to identify sustainable solutions. With the outcome, an Energy Management Strategy (EMS) will be created, Additionally, it includes an analysis of a PV/Thermal system, with Coolworld as a case study.

This thesis addresses a critical challenge in the field of renewable energy, focusing on the efficient utilization of Photovoltaic-thermal (PVT) systems. Much research has already been done on PVT and there exist many thermal simulation models. However, many of the researches done and existing thermal models are restricted to a specific collector archetype which gives less flexibility in experimentation between multiple archetypes. In addition, many experimental researches require a physical setup for measurements and thermal simulation models would need to be altered for different research approaches and collector archetypes. The primary objective of this thesis project is therefore to create a performance simulation framework model that is suitable for the calculation of the thermal and electrical performance for any PVT archetype. It aims to develop and implement a toolbox application encompassing heat transfer models that can establish a foundation for future research on PVT collector optimization, PVT system integration and PVT performance analysis. This toolbox application will be implemented into the PVMD Toolbox Vogt et al. (2022), housed within the Photovoltaic Materials and Devices research group at TU Delft.

Selected PVT collector: This research has visualized that there is a wide variety of PVT archetypes that can be used for current and future generations of PVT collectors. PVT collectors can be combined with heat pumps, refrigeration pumps, phase change materials and multiple forms of heat collection via fluids or air. These combinations can all contribute to high electrical and thermal efficiencies

Numerical heat transfer model and assumptions: It is possible to calculate heat transfer rates of complex designs when using a Finite Element Method (FEM) approach to calculate the heat transfer within the collector. With the proper convective and radiative equations to the environment, the heat transfer inside the collector and to the environment could be calculated without needing an experimental setup.

Performance calculations: The performance calculations gave insight into the simulated behavior of the PVT collector when operating in real-world conditions. Ranging the inclination angle from 0 to 60 degrees showed that the thermal efficiency became around 55% at an irradiance of 800 W/m2 at 45 degrees. It also showed that differences in dimensions like pipe thicknesses and number of pipes did not affect the thermal performance that much. The daily performance calculations illustrated that the thermal energy lost to the environment can be three times as high as the incoming solar energy due to the low ambient temperatures compared to the inflow temperature. In the summer, PVT can achieve high total efficiencies of around 75% making PVT suitable during those times. The economic analysis showed that a PVT collector can have an LCOE of $0.08/kWh which is lower than the $0.13/kWh of conventional PV.

This thesis addresses a critical challenge in the field of renewable energy, focusing on the efficient utilization of Photovoltaic-thermal (PVT) systems. Despite their promising role in sustainable energy production, PVT systems often grapple with excess heat generation, impacting their efficiency and longevity. The primary objective of this research is to explore the synergy between PVT modules and heat storage systems. It aims to develop and implement solutions for effectively storing this surplus heat. This work involves the formulation of new models for heat storage solutions and their assimilation into the PVMD Toolbox, housed within the Photovoltaic Materials and Devices research group at TU Delft. By enhancing the capability of PVT systems to manage excess heat, this thesis contributes to optimizing these systems for broader applications in sustainable energy generation.

This research investigates the performance of a novel building-integrated photovoltaic (BIPV) window solution equipped with bifacial photovoltaic (bPV) cells and reflective Venetian blinds through a PV modelling approach. By modelling this PV window solution in BIGEYE, the study aims to evaluate how different types of blinds and tilt angles can help to boost the overall performance of the bPV window and to quantify the potential energy gains under varying weather conditions. First, the optical model was validated against experimental data to ensure it could accurately simulate the irradiance received at the front side of the window plane. The optical properties of the Venetian blinds were also defined to quantify the irradiance gain at the rear side of the bPV window. Then, the electrical model was also validated to make sure the model could accurately simulate the electrical behavior of the bPV window demonstrators in real operational conditions. The validated models were then used to test the effect of using different blind configurations in the bPV window’s performance.

In this way, three different types of Venetian blinds were tested: S157 (grey colored), S102 (white colored) and V95 (silver colored). The analysis revealed that, when deployed at a tilt angle of 60°, these types of blinds can help to boost the irradiance gain at the rear side of the bPV window by up to 16%, 20% and 25%, respectively, on a fully sunny day. The study also demonstrated that blinds positioned at 60° consistently achieved the greatest absolute boost in temperature-corrected performance ratio (TCPR) of the bPV window over a typical meteorological year (TMY) in Eindhoven, The Netherlands. In this way, the V95 blind type at a tilt angle of 60° demonstrated to be the optimal blind configuration for boosting the performance of this bPV window. Furthermore, an in-depth analysis was conducted to examine the influence of additional factors on the performance of this bPV window, such as the angle of incidence (AOI) between the sun and the blinds' surface normal, which showed to have an inverse correlation with the bPV window’s TCPR, highlighting that the performance of the window tends to decrease as this AOI increases.
Furthermore, the study quantified the Yearly Specific Yield (YSY) boost achievable with the optimal blind configuration, finding that a maximum boost of 19% can be attained on a TMY in Eindhoven, 18% in Stockholm, and 17% in Valencia. The difference in performance across locations is attributed to variations in meteorological and geographical factors, such as diffuse fraction and AOI. Overall, the findings provide valuable insights into how different blind configurations can enhance the performance of this bPV window and contribute to enhance the energy performance of high-rise residential towers and office buildings.

This thesis addresses the imperative need for sustainable energy solutions in the residential sector which is a significant contributor to global energy consumption and greenhouse gas emissions. Focusing on modeling and optimizing residential energy systems, the study explores the integration of photovoltaic (PV) panels, heat pumps, and batteries. The purpose is extending the applications of the Photovoltaic Material and Devices (PVMD) toolbox, offering a framework for future research and advancements. The objective is to enhance energy efficiency, reduce carbon footprints, and contribute to energy security by diversifying energy sources.
The research encompasses a comprehensive analysis of heat pump models, emphasizing their role in space heating, space cooling, and domestic hot water functions. Two specific models are chosen for Coefficient of Performance (COP) and Energy Efficiency Ratio (EER) calculations. These models, along with the utilization of the nPro tool, lay the foundation for integrating heat pump systems with PV production and battery storage in residential buildings.
The study successfully integrates the model of the battery’s performance and the overall grid-connected energy system. Employing a mathematical modeling approach, each component is systematically incorporated into the system, including the previously developed heat pump model. This integration, coupled with the Alternating Current (AC) output of the PVMD toolbox and the battery, establishes the groundwork for subsequent economic and performance analyses of the system.
The study systematically selects various locations with different environmental conditions such as Equivalent Sun Hours (ESH) and average ambient temperature to analyze the economic aspect by checking the Net Present Cost (NPC) and performance aspects by checking Self Consumption Ratio (SCR) and Self Sufficiency Ratio (SSR) of the integration model. The findings emphasize the economic viability of heat pump investments in cities with distinct heating and cooling demands. It has been demonstrated that in colder cities where heating demand is predominant, heat pumps are economically attractive, resulting having heat pumps in optimal scenarios that give the minimum NPC in Amsterdam and Lisbon. Additionally, although the individual components of the system may seem cost-ineffective, their value is derived more from integration in milder cities where heating demand is dominant, resulting having heat pump and PV integrated for the optimal scenario for Lisbon. However, cities dominated by cooling demand face challenges in achieving financially optimal designs because the operational savings for cooling cannot be accurately included such as Cairo and Dakar. The research underscores the importance of considering various system factors, including initial investment costs and electricity tariffs, to achieve financially optimal sizing. As the initial cost of the battery decreases, battery technology becomes economically appealing for Lisbon and Dakar. Moreover, changes in the tariff prove economically favorable for integrating the battery system in Lisbon, Cairo, and Dakar.
This work contributes valuable insights to the field of renewable energy, providing practical solutions for the transition towards cleaner and more efficient residential energy systems.

Batteries play a crucial role in powering contemporary devices and systems, ranging from smartphones and electric vehicles to renewable energy storage. With the increasing demand for more efficient and reliable battery technologies, the need for accurate monitoring and assessment of battery condition and performance has also grown. Online estimators, that continuously analyse battery conditions in real-time, have emerged as valuable tools to meet these goals. This thesis focuses on constructing model-based online state estimators for real-time estimation of a battery's State of Health (SOH).

These estimators, necessitate a state space model for a lithium-ion cell. In the initial part of the thesis, a physics-based reduced-order model (ROM) of a lithium-ion cell is developed. This model accounts for major aging mechanisms such as Solid Electrolyte Interphase (SEI) layer formation, Loss of Active Material (LAM), and Lithium Plating (LIP). To incorporate temperature effects on cell parameters, a simplified lumped thermal model is integrated into the battery model. The model is subsequently transformed into a state space model using the Discrete Realization Algorithm (DRA) process.

Building upon the noisy outputs from the ROM models, a set of five estimators is formulated: State of Charge (SOC), Voltage, SEI loss, LAM loss, and LIP loss estimators. These estimators are constructed based on Kalman filters and collectively contribute to real-time prediction of a battery's SOH. Given their reliance on the model, the ROM model's output is employed as a reference to gauge the precision of the estimators.

To address the real life scenarios and to check the robustness of the estimators, a series of sub-questions were analysed:
Sub question1: How to estimate the SOH of a cell in real-time using adaptive control techniques ?
Sub question2: How fast can the estimator react to changing initial states of the cell?
Sub question3: Can the estimators be adapted to concurrently estimate both the states and the time varying cell parameters in case of an old cell? How fast can this be
achieved in real-time ?

Overall, this research contributes to the development of model-based online estimators, which are poised to have a significant impact on enhancing battery performance, prolonging lifespan, and facilitating the transition towards a more sustainable energy future.

This thesis aims to enhance the performance of solar cells, specifically those used by Solarge, through comprehensive research on optical characterization and texture fabrication.
In the first part, the focus is on understanding and optimizing the optical properties of Solarge's polymer front sheet and encapsulant. Through meticulous measurements, both computationally and experimentally, the thickness and optical constants of each layer are determined. This information is used to develop an accurate optical model, validated against real-world measurements, to simulate the performance of Solarge's solar cell stack. Additionally, electrical performance is thoroughly evaluated using a combination of computational and experimental techniques.
The second part of the research delves into the fabrication of textures on Solarge's front sheet to minimize optical losses. Two fabrication methods, release papers and Teflon sheets, are examined, and a diverse range of texture morphologies undergo rigorous experimental testing. These textures are carefully evaluated based on their optical and electrical characteristics. By analyzing the findings from the initial texture analysis, a set of requirements is established to guide further investigations and determine the most effective texture for Solarge's solar cell stack. A computational study is conducted to accurately simulate and analyze different texture geometries, including scaled-up bio-inspired textures, random pyramids, and corner cubes, using the advanced capabilities of GenPro4 software. Based on the results obtained, two texture geometries are recommended to Solarge for further optimization. The implementation of the first recommended texture demonstrates a significant increase of 2.65% in power output compared to the current Solarge cell stack.
A holistic perspective is provided through a simple financial analysis, evaluating the potential profitability and economic feasibility of implementing the recommended improvements outlined in this thesis. The research findings offer practical insights for Solarge, enabling them to enhance module performance, reduce optical losses, and potentially generate substantial revenue.
In conclusion, this thesis presents a comprehensive investigation into the optical characterization and texture fabrication for Solarge's solar modules. The research outcomes contribute to an improved understanding of the optical properties of the cell stack components and the impact of surface texturing on performance. By combining scientific analysis, experimental testing, and computational simulations, this research offers valuable recommendations to enhance the overall efficiency and profitability of Solarge's solar cell stack.

To make silicon thin film solar cells attractive to the market, their efficiencies should reach the efficiencies of the dominant crystalline silicon solar cell. Therefore the search for ways to improve the efficiency of silicon thin film solar cells continues. TCO front contact layers and back reflector layers play a significant role in the increase of thin film solar cell efficiencies. For the optical characterization of these TCO layers, commonly used methods are found to differ significantly in results regarding the extinction coefficient which makes their accuracy questionable.

This research consists of two main parts. For the first part, the commonly used optical characterization methods spectroscopic ellipsometry and spectrophotometry + data analysis in SCOUT are analyzed in accuracy and compared to newly introduced methods using spectrophotometry + data analysis in GenPro4 and photothermal deflection spectroscopy + data analysis in GenPro4 to build a guide on optical characterization of TCO materials. For the second part, the optical response determined using the software GenPro4 of a double junction silicon thin film solar cell for a novel bi-layer front contact design consisting of IOH and i-ZnO will be compared to the optical response for standard used AZO, and ITO single layers to find the best front contact design. Furthermore, the optical response of a double junction silicon thin film solar cell for a back reflector containing an i-ZnO layer on top of the silver back contact will be compared to the optical response for a back reflector containing an AZO layer on top of the silver back contact to find the best back reflector design.

From the results of the optical characterization methods, it is concluded that photothermal deflection spectroscopy + data analysis in GenPro4 is the most accurate method for determining the extinction coefficient of a TCO material. The results of the optical simulations for front contact TCO and back reflector TCO designs showed that the bi-layer can enhance the optical response of a double junction silicon thin film solar cell significantly compared to the AZO and ITO single layers. The i-ZnO TCO back reflector layer was found to induce less parasitic absorption and therefore a better optical response of the double junction silicon thin film solar cell.

Increasing the energy yield per unit area of Photovoltaic (PV) modules is one of the main challenges the PV technology is currently facing. In search of ways to address this issue, solar tracking systems are a favorable solution, which according to literature can enhance the energy yield by up to 45%. Another way is to opt for high-efficiency solar cells. Tandem cells have emerged as a promising technology, achieving efficiencies of over 30%. The integration of these tandem cells with sun-tracking techniques suggests high-performing solar modules. The present work develops a solar tracking model to simulate the performance of tracking PV systems equipped with tandem modules. The model will be incorporated into the PVMD toolbox, a PV modeling software developed within the PVMD group. This software can predict the energy yield of PV systems using self-consistent models for each aspect of the energy conversion.

The current version of the toolbox makes it impractical to include solar tracking due to the time-consuming nature of ray tracing used to compute the irradiance. Ray tracing generates sensitivity values that illustrate how sensitive is the module to incoming irradiance from any direction in the skydome. Initially, this work focuses on substituting ray tracing with an alternative faster approach to express sensitivity based on view factors. The view factor and ray tracing method are compared with respect to computational time and extent of agreement. It was found that the view factor can significantly reduce the computational time from over 12 minutes, as required in ray tracing, to a few milliseconds for a single module orientation. Additionally, the view factor method generates sensitivity values closely matching those from ray tracing. For instance, a mean RMSE of 1.2% between the two methods is achieved, for an albedo of 0.2 and module tilt of 30 degrees. Sun tracking aims to locate the module orientation that maximizes the in-plane irradiance. Directly calculating the irradiance for every orientation to identify the optimal, is not a viable option, as it requires substantial
time. Thus, sun tracking was expressed as an optimization problem and algorithms were employed to address it. Based on the prevailing sky conditions three optimization case studies were defined on an hourly basis: sunny, cloudy, and intermediate hours. Multiple algorithms were compared across the three cases with selected criteria the convergence to the optimum and runtime. Matlab’s surrogate solver and an author-developed algorithm were selected, as a satisfying solution, compromising those two criteria.

Finally, energy yield simulations were performed on perovskite-silicon tandem modules mounted on a dual-axis tracking system. Four locations were selected, representing different real-world conditions: Stockholm, Athens, Bombay and Bogota. Results show the module’s tilt dynamic adaptability to sky conditions: increas- ing nearly to the sun’s zenith when direct light dominates, and lowering when diffuse light is prevalent. Furthermore, the seasonal fluctuations of the energy gain of tracking systems are explored, with locations further from the equator such as Stockholm exhibiting the highest variability of 19% in winter to 36.9% in summer. In addition, the annual energy gained among the locations was found to span between 24.8% (Bogota) and 34.1% (Bombay). An important finding is the direct proportionality in gains from absorbed irradiance to DC and AC yields, illustrating a 1:1:1 ratio. Then, the effect of tracking technology on mismatch losses of tandem modules was examined. Results indicated that tracking has little impact on both the current and power mismatch. For example, the power mismatch losses slightly increased from 1.10-1.46% in static PV systems to 1.29-1.77% for tracking topologies in the locations examined. Moreover, the tandem’s annual energy gain is compared to silicon heterojunction modules. The analysis showed similar gains across locations for both cell technologies.

Tandem technology has emerged as one of the most promising innovations in the field of photovoltaics. Higher conversion efficiencies than standard single-junction cells have already been achieved. Proving how these laboratory conversion capabilities translate into real-world performance is therefore a main interest drive within the photovoltaic research community.

Typically, photovoltaic device performance is assessed in Standard Test Conditions (STC). For the majority of climates, this is however not representative of actual operating conditions. With the aim of studying potential system applications, the energy yield prediction method adopted in this thesis analyzes tandem technology performance considering real-world conditions. For this scope, the PVMD Toolbox for PV system modeling is employed.

The tandem device investigated in this work is a perovskite/c-Si based structure in a two-terminal architecture. In particular, a TU Delft own poly-SiOx based crystalline silicon bottom cell is utilized in the configuration. This structure is implemented in the Toolbox to carry out Optical simulations from cell to module system level. Operating conditions are introduced through use of the Toolbox Weather and Thermal models. These recreate real-world illumination and climate settings for the selected locations of Reykjavik, Rome and Alice Springs. With an STC-optimized perovskite thickness of 515 nm, the hourly implied photocurrent density of the device is calculated and validated. The jph annual average is 1.92, 3.34 and 5.01 mA/cm2 for the three locations, respectively. These values take into account a sub-cells current mis-
match loss between 5 and 8% depending on location. To reproduce real-world cell electrical parameters behavior, the variable irradiance and temperature sub-cells J-V curves have been obtained. A poly-SiOx based silicon prototype was tested in laboratory settings and its curves then utilized in simulations after measurements validation.

The module annual energy yield is computed through simulations with the Toolbox Electric model. In terms of specific DC yield, the STC-optimized module delivers 820, 1,427 and 2,161 kWh/kWp/year in the three locations. The power mismatch lowering effect due to the fill factor gain compensates the current mismatch in this 2T configuration, reducing energy mismatch losses. This performance is then compared to a reference single-junction poly-SiOx based silicon module, to show how tandem technology potentially outperforms standard modules differently depending on climatic conditions. The tandem module is also assessed in terms of DC performance ratio (PR), exhibiting values over 0.94 for all three locations. The structure is then real-world optimized by varying perovskite thickness, with the goal of maximizing
location-specific energy yield and PR. Slight improvements are obtained for the Reykjavik and Alice Springs locations, where the energy yield increases by few relative percentage points along with PR.

Photovoltaic (PV) materials are gaining rapid popularity for their use in commercial solar cell applications. Due to the growing need for high efficiency solar cells, new materials such as perovskites are being researched. While the conventional experimental methods are still used to test new PV materials, PV modelling is gaining importance as an efficient and cheap alternative to physically synthesizing and testing each new material. In the PVMD group at TU Delft, multiple stages of modelling PV materials to study their efficiency have been researched, however, an ab initio method to obtain fundamental opticaland electrical properties of new materials is currently absent. While these properties are currently studied using experimentation, this thesis aims to provide a reliable simulation procedure to calculate the optical and electrical properties of PV materials using Density Functional Theory (DFT) softwareand verify its accuracy.
 
The fundamentals of DFT and its implementation in DFT software are first studied to better understand the Vienna Ab Initio Simulation Package (VASP) software, on which simulations are performed during this thesis. The VASP software is a plane wave classical DFT software that employs the Projector Augmented Wave (PAW) method for electron structure calculations and has a wide range of electron density functionals available in its library making it a perfect fit to study optical and electrical properties of materials using DFT. 

Based on their success in previous computational research on material properties, the PBE and HSE06 electron density functionals are used in this thesis for simulations. A step-by-step procedure is then developed for simulations on the VASP software using both the PBE and HSE06 functionals detailing every step involved in the simulation, the inputs required at each step and the configuration of the input files at every step in order to obtain the density of states, band structure, band gap and complex refractive index for PV materials. Monocrystalline Silicon, a wellstudied PV material is then used as acase study to examine the accuracy of the developed procedure. 

The procedure is then employed to study new and promising solar cell materials such as inorganic halide perovskites and inorganic perovskites with mixed halides. Multiple simulations are performed to study the variation in the band gap and complex refractive index of inorganic perovskites as the composition of the halides is changed. Finally, the trends visible in the properties of the different perovskites are analyzed to better understand the usefulness of the VASP simulations. Finally, recommendations are provided for future research into the study of PV material properties using DFT software such as VASP.

To complete the energy transition, a high efficiency for photovoltaic (PV) modules is desirable to reduce the needed material and surface area (per unit of generated electrical energy). The tandem PV technology has the potential to increase the efficiency of PV modules over 30%. In order to design efficient solar cells, a quantification of the different losses is important. Moreover, research in the losses of PV system has resulted in important insights for PV technology.
This work introduces a comprehensive model for quantifying the different loss mechanisms in a PV system with tandem cells. The loss analysis model will be added to the PVMD Toolbox, which is a software developed at Photovoltaic Materials and Devices group at Delft University of Technology.
This software can be used to simulate the energy yield of a PV system at any given location. In the loss analysis model, 17 losses are defined and divided into four categories (fundamental, optical, electrical and system losses).
The developed model will be used to analyse the loss distribution under different operating conditions for four different PV modules. These different modules are a mono-facial crystalline silicon, a bifacial crystalline silicon, a two-terminal perovskite/silicon tandem, and a three-terminal perovskite/silicon tandem module. The design of these modules is based on a >29% efficient perovskite/silicon tandem cell, fabricated by HZB.
The loss distribution of every module is simulated for Standard Test Conditions (STC) and for real word conditions at four geographical locations. Generally, we find that modules operating in tropical high irradiance climates have the lowest efficiency. For all locations, the difference in losses compared to STC follow similar trends. When the two-terminal perovskite/silicon module is simulated at STC, the loss distribution of the fundamental, optical, electrical, and system losses are 54.8%, 8.9%, 8.5%, and 0.1%, leaving a DC module efficiency of 27.7%.
At real-world operating conditions, various differences can be found. The most significant differences are the thermalization, reflection, and recombination losses, which increase with 1.4%, 1.1%, and 0.5% respectively for the two terminal perovskite/silicon tandem module. Furthermore, the simulated two-terminal module has a higher efficiency than the three-terminal modules for all operating
conditions due to lower mismatch losses.
Additionally, this study was able to quantify the fill factor gain for two-terminal devices. Due to spectral variations, there can be a mismatch between the absorbed current in the top cell and bottom cell, which can lead to losses. However, this loss is partially compensated by an increase in fill factor. For example, a current mismatch of 7.0% is reduced to a power mismatch loss of 1.2%, due to an increase in fill factor. Therefore, the power mismatch should be used as an indicator for mismatch losses instead of the current mismatch.
Finally, this study simulated different improvements on operating conditions. The results show that solar tracking does not only increase the in-plane irradiance of the PV system, but can also increase the efficiency. For example, dual-axis tracking can increase the efficiency with 1.1%. Also, the gain of active cooling is simulated and quantified. The increase of efficiency when cooling at 20oC
compared to a PV system without cooling is around 0.4%, mostly caused by decrease in emission and recombination losses. Furthermore, the optimal perovskite thickness for real world conditions is found, by simulating different thicknesses for the perovskite layer. The results shows that the optimal
thickness under STC (575 nm) is also optimal under real-world operating conditions. Finally, the optimal bandgap energies for reducing the fundamental losses are found for tandem cells. For all conditions (including STC), the optimal bandgap energies for the top and bottom cell are 1.73 and 0.94 eV respectively.