Achieving carbon-neutral energy systems in industrial clusters necessitates fundamental restructuring of existing energy systems. This transition is accompanied by several significant challenges. In pursuit of carbon neutrality, there is an increasing demand for industrial electrification, as well as a rising demand for green electricity and sustainable energy carriers, such as hydrogen and ammonia. The integration of variable renewable energy sources (VRES) is critical to address the growing demand for clean energy and enable the critical shift away from fossil fuel dependence. However, the intermittent nature of VRES, in combination with grid congestion issues, poses a challenge to the reliability of energy supply, a crucial element in fostering an attractive investment climate. Moreover, the development of new energy infrastructure is constrained by several factors, including limited access to new grid connections, investment uncertainty, and spatial limitations. Conventional energy planning and operation approaches, which treat energy sectors in isolation, are unable to address these complex, system-wide challenges. These approaches limit the ability to optimize across various energy sectors and fail to harness the potential synergies between energy carriers. Conversely, a more flexible and integrated approach provided by multi-energy systems (MESs) has been shown to effectively mitigate VRES intermittency, alleviate grid congestion through alternative energy pathways, and enhance cross-sector synergies and infrastructure utilization. However, the realization of these benefits necessitates a deeper understanding of the operation and organization of such systems.

To provide these insights, this research develops a model-based optimization approach for the cost-effective operation of MESs. The modeled system represents a synthetic, future-oriented energy system for an industrial cluster, drawing inspiration from the Maasvlakte area in the Port of Rotterdam. The research introduces a new operation strategy to support the transition towards a carbon neutrality, addressing key barriers currently limiting the decarbonization of industrial clusters.

A detailed conceptual model for the synthetic MES was developed to reflect the existing infrastructure of the Maasvlakte area, planned projects, and potential future developments. This conceptual model was translated into an operational optimization model implemented in Python using the PyPSA toolbox. The MES integrates five energy carriers—electricity, natural gas, hydrogen, ammonia, and heat—within a unified model through the energy hub approach that facilitates sector coupling, conversion, and storage within multi-energy carrier networks. The electricity system is modeled with physic-based power flow constraints to capture technical feasibility in the power system, and the non-electrical carrier networks are modeled using the energy hub approach. The entire system is optimized through a single-objective cost minimization, with mixed-integer linear programming, using hourly resolution over a one-year horizon. To test the system's performance under varying renewable energy supply, three weather-dependent scenarios were formulated and optimized, reflecting variability in wind and solar conditions and its implications for system operation.

Based on the system’s optimal performance across all scenarios, this research proposes a new operation strategy that enables flexible and cost-effective operation of a multi-energy industrial cluster, representing a paradigm shift from conventional approaches. Instead of relying on static, price-driven, and siloed sectoral operation, the proposed strategy emphasizes cross-sector economic optimization, dynamic dispatch response to system states, enhanced system flexibility through integrated conversion and storage technologies, and continuous energy supply to industrial consumers.

Key outcomes include the development of an operation strategy that minimizes costs while ensuring energy supply to industrial consumers and technical feasibility, the identification of ammonia as key flexibility provider, and actionable insights into flexibility management, the role of conversion technologies, and infrastructure planning. The results have important implications for decarbonization pathway of industrial clusters, offering a cost-effective and actionable approach to integrated energy system operation.

Emerging PV technologies like Perovskite has lead to the development of Perovskite/Silicon (Pvk/c-Si) tandem device (Multi-junction device) and has now gained a lot of momentum and attention due to the fact that the tandem device can reach a Shockley-Quisser limit of about 44.1% efficiency. But to speed up its development, a lot of emphasis is made on conducting tandem solar cell device simulations to have get a good idea on the experiments that can be carried out. Solar cell simulations for tandem devices are carried out in advanced 2D/3D solar cell simulators like SETFOS or Synopsys TCAD Sentaurus. These softwares have large computational time and have complex user interface making simulations challenging. There are 1D solar cell simulators like ASA (Advanced Semiconductor Analysis) developed at TU Delft that has less computational time with an easy and intuitive interface. But ASA does not have the appropriate tunnelling models to simulate the tunnel recombination junction characteristics of perovskite silicon tandem devices.

To make ASA a complete software suite for simulating perovskite silicon tandem device, tunnelling models proposed by Ieong et al. is used for both direct and band to band tunnelling. These tunnelling models use basic inputs like band energy data, electrostatic potential data and electric field data for a particular device and outputs the tunnelling generation rate that can simply be added to the continuity equations for electrons or holes during the simulation of the device. A fully fledged algorithm was designed for the automation of the direct tunnelling and the band to band tunnelling process with limited input from the user while using the models proposed by Ieong et al. In simple terms, the algorithm takes in the required input and scans through the device for every interface to check for tunnel contributions and performs calculations when necessary. All necessary conditions are included inside the algorithms to ensure that the simulation is accurately solved.

The validation of the newly developed tunnelling algorithm was commenced for PN junction, Silicon hetero-junction and finally the Perovskite-Silicon tandem device. The JV curve for the above device simulations with and without incorporated tunnelling models was extracted and a comparison was made with literature results and simulation results from other software suites. The newly developed tunnelling algorithms was concluded to be accurate. The JV curve obtained from the ASA simulation showed good agreement with literature results and simulation results from other software suites with error percentages of less than 3% for open circuit voltage, short circuit current and fill factor. With proper tuning of the device layer thickness, texturing on multiple layers for the tandem device and enhancing the mobility of the non-absorber layers for the perovskite top cell, further improvement can be expected in the simulation. These methods can eventually lead to reaching the Shockley Quisser limit of about 35.7% efficiency for the perovskite silicon tandem solar cell even when general opto-electrical losses are taken into account.

As the efficiency of silicon (Si) photovoltaic (PV) moves ever closer to the theoretical limit, 2-junction PV becomes increasingly interesting. Since PV cells are tested under standard test conditions (STC), but real world working conditions differ, it is interesting to see how 2-junction PV performs worldwide in different climates. Worldwide spectra where simulated in SMARTS using data from NASA’s Global Land Data Assimilation System (GLDAS), Clouds and the Earth’s Radiant Energy System (CERES) and Socioeconomic Data and Applications Center (SEDAC) and from the Joint Institute for the Study of the Atmosphere and Ocean (JISAO). SMARTS provides only clear-sky spectra, to account for cloudiness, the BRL model is used. The top absorber is 1.72 eV Perovskite and the bottom absorber is 1.12 eV Si. Because Si is an indirect bandgap material, a limiting Efficiency model by Richter et al. is used that takes both Auger and radiative recombinations into account. Because this model relies on variables and constants only given for Si, and the top absorber is a direct bandgap material, the detailed limit model by Shockley and Queisser is used to calculate the performance of Perovskite. The distribution of high and low local yearly average irradiance is overall realistic, except for the north of Africa and the Middle East. Here aerosol optical depth (AOD) values are elevated. The elevated AOD can be explained by dust events, still these areas should be among the ones with the highest irradiance. The AOD effects the blue side of the spectrum mostly. All spectra where normalised using CERES’ irradiance data. The Richter model is thickness dependent. Thus the optimal thickness of Si is determined to find the optimal efficiency. To distinguish between the effects of the top layer and local climate effects on the thickness, firstly the optimal thickness of single junction Si is calculated and analysed. The optimal thickness ranges from 70 to 870 µm globally. The average is 205 µm and the irradiance weighted average is 165 µm. For double junction Perovskite - Si current matching was used to find the optimum. The thickness of Si ranges from 10 to 4500 µm. But only nine locations (of 597) have a thickness above 500 µm. The average thickness is 77 µm and the irradiance weighted average is 81 µm. Locations with a high optimal thickness had a blue-er spectrum than the locations with a low thickness. Using the optimal thickness of single junction Si and current matching, the optimal top-bandgap was determined around the world. The optimal bandgap ranges between 1.55 and 1.76 eV, the average is 1.655 eV and the irradiance weighted average is 1.663 eV. The relation between the top bandgap and optimal Si thickness was determined under STC. High bandgaps had the lowest optimal thicknesses and the thickness increased with decreasing top-bandgap. Alterations in spectrum and temperature where applied as well to find the effect on that relation. Decreasing temperature and airmass both resulted in an increase in optimal thickness per bandgap vise versa. Changing the spectrum has a greater effect than the temperature change.

Due to the high-efficiency potential over 40%, the two-terminal (2T) perovskite/c-Si tandem solar cell becomes a desirable and promising candidate for solar cells. The photovoltaic materials and devices (PVMD) group in TU Delft has developed the c-Si solar cell using poly-SiOx as carrier-selective passivating contacts. The utilization of poly-SiOx as carrier selective passivating contacts is relatively new and very interesting to be analyzed as its bandgap can be varied by changing its oxygen content. This can be used in the solar cell to increase the Jsc. In this work, the 2T perovskite/c-Si tandem solar cells' optimization has been conducted by means of optical and electrical simulations. Optical simulations of the 2T, 3T and 4T perovskite/c-Si tandem solar cells in GenPro4 are presented. The main objective is to show the new type of bottom cell's optical performance in the 2T, 3T, and 4T tandem solar cell. Furthermore, the two-terminal (2T) perovskite/c-Si tandem solar cell's electrical modeling framework with the new type of the bottom cell has been developed. In this model, the optical generation profile from GenPro4 was successfully imported into the semiconductor simulations software called Sentaurus TCAD. The perovskite and c-Si solar cells have been optimized separately. The perovskite solar cell optimization was conducted by changing parameters such as contact resistance, surface recombination velocity and thickness of each layer. This leads to the increase in the perovskite solar cell efficiency from 15.83% to 21.50%. This top cell was combined with a c-Si bottom cell with an efficiency of 25% to form a two-terminal (2T) tandem solar cell. The two-terminal (2T) perovskite/c-Si was further optimized by optimizing the tunnel recombination junction. The optimization of TRJ was done by varying the doping concentration of indium tin oxide (ITO) and spiro-OMeTAD, respectively. As a result, the 33.70% efficiency of the two-terminal (2T) perovskite/c-Si tandem solar cell was obtained.

Although front and back contact silicon heterojunction solar cells exhibit promising external parameters, they are limited by the front highly absorptive doped layers. Due to their opto-electronic properties, research and development groups have demonstrated that transition metal oxides (TMO) are potential alternatives for doped layers in solar cells. In particular, molybdenum oxide (MoOx) is a good candidate for the p-contact layers. This thesis presents an investigation of the introduction of MoOx in the front contact of solar cells. To this purpose, the evolution of the passivation is evaluated along the fabrication process together with temperature sensitivity. The application of the layer negatively influences the passivation quality. Moreover, the passivation quality decreases more after annealing and transparent conductive oxide (TCO) deposition. We mitigate such issues by treating the surface of the passivation layer before MoOx application. The optimized contact stack shows implied open-circuit voltage above 715 mV and lifetime 1.57 ms. Finally, the contact stack is implemented in solar cells demonstrators. The best solar cell exhibits a short circuit current density (JSC) equal to 35.64 mA/cm2, an open-circuit voltage (VOC) of 690 mV, a fill factor (FF) of 77.29% and a total efficiency (η) of 19.01%.

Nowadays, silicon heterojunction (SHJ) solar cell is one of the most promising photovoltaic technologies thanks to the outstanding passivation quality from the a-Si:H layers. Together with the interdigitated-back-contacted (IBC) architecture, it enables the highest efficient, 26.7%, single junction c-Si solar cell. However, the mass production of such high efficient solar cells is limited, due to the complexity of the solar cell processes and the involved expensive TCO layer(s). The objective of this thesis is to develop high efficiency, simple processed IBC-SHJ solar cells. To accomplish this goal, a comprehensive study ‘from layer to device’ is conducted: firstly, the focus is on the contact stacks deposited via PECVD, which includes intrinsic and doped hydrogenated amorphous silicon (a-Si:H) and nanocrystalline silicon oxide (nc-SiOx:H) thin-film layers; Then the optimized passivation contact stacks are used in the front back contacted (FBC) solar cells, with which the factors that limit the fill factor (FF) and open-circuit voltage (VOC) are identified; Lastly, a simplified process is developed to fabricate tunneling IBC-SHJ solar cells. The influences of PECVD deposition parameters on passivation quality and carrier selectivity of the passivation and contact layer stacks were intensively studied. With the optimized 6 nm thick intrinsic a-Si:H layer an effective lifetime over 3 ms and implied-VOC (iVOC) beyond 720 mV are achieved on double side textured c-Si. Enhanced passivation qualities with iVOC of 729 mV is obtained by adding the field effect passivation from the optimized n-type a-Si:H and nc-SiOx:H layers on top of the excellent chemical passivation induced by the optimized 10 nm thick intrinsic a-Si:H layer. On the other hand, with the optimized intrinsic a-Si:H passivation layer, the deposition of p-type a-Si:H or nc-SiOx:H does not deteriorate the overall passivation quality. Besides that the optimized p-type nc-SiOx:H layer exhibits excellent activation energy of 51.4 meV, which closes to the optimal value for a high efficient hole selectivity, and a dark conductivity of 0.174 S/cm, which is high enough to facilitate the hole transport. Research on FBC-SHJ solar cells reveals that thicker p-type nc-SiOx:H layer is essential to ensure a smaller/no drop from SunsVoc to VOC, which is related to minority carrier collection. Besides, such a thick doped nc-SiOx:H layers can effectively shield the device precursor from the influence of ITO’s field effect and keep the overall passivation quality after ITO sputtering. Accordingly, the best FBC device shows promising results in terms of SunsVoc with 727 mV and 734 mV, pFF of 0.862 and 0.841, measured before and after metallization, respectively. By implementing 3 nm n-type nc-Si:H instead of directly n-type nc-SiOx:H in contact with ITO, FF improves from 0.56 to 0.73. The best manufactured FBC-SHJ solar cell (7.84 cm2) exhibits VOC of 710 mV, EQE short-circuit current density (JSC,EQE) of 39.4 mA/cm2, FF of 0.73 and efficiency of 20.4%. For IBC-SHJ solar cells manufacture, the lift-off patterning approach is proved to be not suitable for processing double side textured cells, mainly due to the fact that the doped nc-SiOx thin film alloys is not HF resistant. However, by applying this non-HF resistant property of the doped nc-SiOx alloys, a novel wet-chemical approach for processing tunneling IBC-SHJ solar cell is developed. This patterning approach allows to simplify the process. And the tunneling structure avoids the patterning step of the p-type nc-SiOx:H layer. The first preliminary IBC device demonstrated with this approach exhibits VOC of 659 mV, JSC of 41.30 mA/cm2, FF of 0.67, and efficiency of 18.2%. Further optimization on the thickness of the intrinsic a-Si:H layers induces an excellent VOC of 719 mV with an average VOC of 715 mV over 7 cells, JSC over 41 mA/cm2. However, the low FF (<0.60) is limiting the cells performance, which is mainly attribute to the low conductivity of the n-type nc-SiOx:H layers.

In this thesis, contact resistivity for carrier-selective contacts (CSCs) is evaluated by using finite element simulations TCAD Sentaurus. First, the process of transmission line measurement (TLM) is modelled and validated based on current-voltage (I-V) data comparison between reference experiment and simulation results on polycrystalline silicon (poly-Si) based CSCs. Simulation and experimental data are in a good agreement, thus confirming that the modeling method accurately describes the main physical mechanism. Therefore, the simulation approach is used to evaluate the resistivity of complete contact stack for poly-Si and silicon heterojunction (SHJ) based CSCs. Simulation results reveals that the contact resistivity exhibits a clear dependence on tunneling mechanisms in terms of potential barrier size and band alignment. For poly-Si based CSCs, SiO2 thickness (potential barrier size) is the prevalent parameter impacting on the contact resistivity. Additionally, proper doping in poly-Si and buried region in c-Si can improve the band alignment, thus the contact resistivity becomes more resilient to the effect of the tunneling barrier. For SHJ based CSCs, low contact resistivity values are achieved with high carrier concentration in TCO and low activation energy in doped thin film silicon layer. In general, low activation energy reduces the potential barrier for carrier transport while high TCO carrier concentration allows a better band alignment. In particular, for p-type contact, high carrier concentration in TCO is crucial to ensure an efficient band alignment for band-to-band tunneling at TCO/doped-layer interface. Additionally, the contact resistance depends also on the bandgap and the thickness of the passivating intrinsic amorphous silicon (i-a-Si:H) as they impact on band alignment and also energy barrier size. Indeed, lower values of contact resistance are calculated for thinner i-a-Si:H and narrow bandgap because the reduction of the potential barrier opposing to hole collection. Finally, the presented simulation platform has the potential and flexibility of predicting the contact resistance for any type of CSC stack in terms of materials and number of layers.