The Dutch energy transition is driving a rapid expansion of intermittent renewable energy sources, significantly increasing the need for grid flexibility. To maintain system stability, the Dutch transmission system operator (TenneT) has identified a requirement for 10 GW of battery energy storage systems (BESS) by 2030, proposing a heuristic geographic distribution based on projected regional renewable surpluses.

This research evaluates the impact of TenneT’s proposed distribution, determines the mathematically optimal siting and sizing of 10 GW of BESS to minimize short-run marginal costs, and assesses how this distribution adapts under three distinct 2030 grid scenarios defined by Netbeheer Nederland. The Dutch high-voltage grid was modeled using Python and the PyPSA framework. To overcome the computational burden of linear programming on a full-year dataset, time series aggregation via hierarchical clustering was utilized to condense the data into 12 representative days.

Simulations demonstrate that while TenneT’s proposed distribution successfully lowers grid costs and reduces renewable curtailment, a mathematically optimized distribution yields superior economic performance. By concentrating battery capacity in specific high-value locations, the optimized model generates an additional €20 million in annual savings compared to TenneT’s maximum deployment proposal. However, applying this optimization to the 2030 scenarios reveals that future grids will face much heavier constraints, necessitating a more granular and evenly dispersed battery distribution across the country.

Sensitivity analyses indicate that the highly meshed nature of the Dutch high-voltage grid renders the absolute financial differences between various geographic distributions extremely small—less than 0.1%. Consequently, while optimizing battery placement at the transmission level provides tangible economic benefits, extreme precision in geographic siting offers diminishing returns. Future research should incorporate multi-year weather dynamics, cross-border market integrations, and a shifted focus toward distribution-level grids to fully realize the potential of battery storage in the Netherlands. ... Read more

High-efficiency flexible thin-film silicon solar cells fabricated on temporary aluminum substrates offer substantial deployment advantages for building-integrated and flexible photovoltaics. However, releasing these devices via wet chemical etching in sodium hydroxide (NaOH) poses severe mechanical challenges. While a triple-layer SiOxNy/SiNx/SiOxNy barrier stack provides adequate chemical protection, residual stress release during aluminum dissolution frequently leads to wrinkling, buckling, and film cracking.

In this work, 29 samples were fabricated and evaluated to decouple and mitigate these failure mechanisms using laser scanning confocal profilometry and dark I-V characterization. Systematic investigations evaluated varying mid-etch annealing temperatures (100–140°C), pre- and post-etch thermal treatments, and stack architecture modifications, specifically introducing a continuous full-area aluminum back contact and an intrinsic Zinc Oxide (iZnO) interlayer.

Results demonstrate that stack architecture modifications yield the most significant improvements: a full-area aluminum back contact reduces average buckle height by 29–36% and markedly suppresses sample-to-sample scatter. The iZnO interlayer recovers roughly 43% of this benefit, demonstrating that both added mechanical stiffness and physical separation from the EVA encapsulant contribute to film stabilization. The most promising process configuration, combining a full-area back contact with a 70°C pre-anneal and a 120°C mid-anneal, provides a baseline for advancing mechanically robust, barrier-integrated flexible solar foils. ... Read more

This project was made to accompany an NLT-module by creating an interactive sound sculpture to motivate high school students into STEM-fields. The report discusses multiple solutions to this problem and picks one to turn into a prototype. The sound sculpture has been divided in two parts: Signal Processing and hardware & Sensing. The modules are checked against an agreed upon programme of approach between the project team and its client. The prototype shows promise but cannot yet be rolled out as a standalone product as in classroom test have not been performed. Once complete, the sound sculpture will help students understand the principle of soundwaves, physics and electrical engineering by giving an interactive learning approach. ... Read more

Industrial decarbonization is increasingly driving interest in on-site solar generation, yet hazardous classified liquid bulk terminals present a uniquely constrained setting in which photovoltaic (PV) deployment must be reconciled with stringent safety, regulatory, and operational requirements. This thesis addresses that challenge through two linked objectives: first, the development of a structured, risk-based, expert-elicited framework to qualitatively rank the suitability of locations within such terminals for PV placement; and second, a quantitative assessment of the achievable PV energy yield at a promising location, using the PVMD Toolbox applied to a case study of Euro Tank Amsterdam (ETA) in the Amsterdam–Rotterdam–Antwerp (ARA) region.

For the suitability assessment, seven main criteria and seventeen sub-criteria were constructed from a combination of industry standards (including the Seveso III, ISO, Omgevingswet, IEC, NEN-EN, ATEX, and PGS frameworks), expert experience, and academic literature, with an emphasis on the risks
introduced by PV installation in a hazardous-classified environment. Two multi-criteria decision-making (MCDM) methods, the Analytic Hierarchy Process (AHP) and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), were combined to weight the criteria and rank ten candidate
locations identified through a spatial inventory of the site. A safety hard-gate veto was introduced as a novel element of the framework; the AHP weighting independently confirmed safety as the most important criterion, consistent with industry practice. Of the ten candidate locations, six were found suitable, with the piping supports and tank shells identified as marginally suitable cases requiring further detailed engineering and risk assessment before deployment. A ten-percent sensitivity analysis on the closeness-coefficient thresholds confirmed the robustness of the ranking.

The tank shell was selected for detailed yield modelling on account of its large available surface area and the novel modelling questions posed by its curved, vertical geometry at the system level. The site was modelled to represent the installation as closely to reality as possible: a dedicated module placement algorithm was developed to populate the cylindrical wall, and a perovskite/perovskitetandem module was simulated with the PVMD Toolbox across a full year of Amsterdam weather data, for both landscape and portrait placement orientations and across the cardinal directions. The results show
that placement orientation (landscape versus portrait) has only a minor effect on yield (on the order of one to four percent), whereas the facing direction is decisive: east-, west-, and south-facing modules substantially outperform north-facing ones. Because the modules are vertically mounted, the plane of-array (POA) irradiance, which captures the azimuth-corrected angle of incidence governs the yield, rather than the global horizontal irradiance alone. A pronounced seasonal effect was identified in which monthly yield peaks in spring rather than mid-summer despite the higher summer irradiance; a highly
plausible cause of this offset which is shown in the in the POA-to-DC conversion efficiency is not to thermal derating, since module temperatures remain mild throughout the year, but mainly to inter-tank shading arising from the prevailing geometry and possibly angle of inscidence reflection. The performance across different tank arrangements was found to depend strongly on the number of unshaded cells, demonstrating the impact of inter-tank shading.

Aggregating the simulated yield across the full terminal with Benzolweg, chosen as the main site of interest demonstrated that PV installed on the tank shells alone, without the inclusion of storage or other demand-side measures could generate roughly 2.45 times the site’s annual electricity demand, yet owing to the strongly baseload-dominated and continuous nature of terminal operations and the intermittency of solar availability, could cover only about 38% of that demand directly. This reveals a fundamental trade-off between self-consumption and self-sufficiency that must be balanced when sizing the system and constructing a viable business case. The thesis concludes with recommendations for fuzzy MCDM extensions, broader expert elicitation, a curved-surface optical and electrical modelling capability for system-level applications, and the integration of energy storage to address the temporal mismatch between generation and demand. ... Read more

The transition to renewable energy, led by photovoltaic (PV) energy, is critical for a sustainable future. However, the current linear ”take-make-waste” economy, also used for PV modules, presents a significant challenge to long-term sustainability, creating a massive future waste stream and reliance on virgin materials. The primary obstacle to achieving a circular economy for solar modules is the use of permanently cross-linked solid encapsulants like Ethylene Vinyl Acetate (EVA), which bond all components together and severely hinder repair, reuse, and high-value recycling. This thesis examines liquid encapsulation as a promising alternative design-for-recycling concept, enabling simple disassembly and material recovery. The primary objective was to determine if liquid encapsulation is a viable alternative from an optical perceptive, compared to conventional solid (EVA) and gas-filled (air) module designs. To achieve this, three sub-goals were formulated and completed. First, a comprehensive selection strategy was developed based on critical optical, electrical, chemical, and thermal criteria, identifying seven candidate liquids for analysis: deionised water, glycerol, SolaPro Ennogreen glycol, Polydimethylsiloxane (PDMS), and three industrial dielectric oils (Shell Diala S4 XZI, Midel 7131, Mivolt). Material compatibility tests with polyisobutylene (PIB) immersed in Midel 7131 and Shell Diala, confirmed that Shell, and therefore mineral oils in general, are incompatible with the use of PIB as a sealant. Second, the complex refractive index (n and k) of these liquids was experimentally measured over the 300–1200 nm solar spectrum using a novel hybrid method. This involved a specialised ellipsometer and dual cuvette measurements with spectrophotometry, generating the nk data needed for detailed optical modelling. Measurements made by Semilab’s liquid-specialised ellipsometer using a 2-term Cauchy model yielded excellent fits (R2 > 0.97) for all liquids, in good agreement with literature values. The dual cuvette method revealed extremely high transparency for all liquids, even slightly yellowish fluids Midel and Shell Diala. A SNR analysis established a confidence threshold at k ≈ 5 ∗ 10−8. Finally, these optical properties were used as inputs for detailed optical modelling and simulation, in GenPro4, to quantify and compare the photocurrent generated by liquid encapsulation compared to standard EVA and air, in various solar module configurations. The optical model and its simulated output are validated through experiments and datasheets, showing excellent agreement around the Δ Jph = 0.2 mA/cm2. The results revealed a fundamental trade-off: while the liquids have lower refractive indices, leading to higher initial reflection losses compared to conventional EVA with UV blockers, their superior transparency resulted in lower parasitic absorption. This balance allowed top-performing liquids, notably Mivolt (highest photocurrent and lowest reflector, Jph = 40.90 41.81 mA/cm2) and PDMS (lowest absorber, Jph = 40.85 41.75 mA/cm2), to generate a photocurrent comparable to, and in some cases higher than, UV-transparent EVA (Jph = 40.92 41.81 mA/cm2). However, the optical performance of the other liquids was very close (especially Midel and Shell, but also glycerol and glycol, followed within 0.17 mA/cm2), meaning that based on optics alone, they should not be excluded, as other design benefits might justify their selection. A critical insight emerged from annual energy yield simulations, which demonstrated that PDMS delivered the highest yearly energy output (0.07% higher than EVA-UVT, 0.086% to Mivolt), due to its extremely low absorption. The simulations showed that mitigating reflection losses through tailored Anti-Reflection Coatings (ARCs) or glass texturing can further unlock the full potential of liquid-encapsulated modules. In conclusion, this thesis provides the first comprehensive optical validation for liquid encapsulation in standard silicon PV modules. It successfully demonstrates that, from an optical standpoint, liquids are a highly viable technology, worthy of further research. Their primary drawback of higher reflection is compensated by superior transparency and can also be further mitigated with existing ARC and glass texturing technologies. This work establishes a robust foundation for future research, confirming that liquid encapsulation is not only a promising pathway toward a circular economy for PV but is also an optically competitive alternative to established solid encapsulants. ... Read more

The proposed thesis aims to develop innovative isolated DC-DC power converter topologies that enhance efficiency and scalability for sustainable energy technology applications. The research begins by optimizing the parallel differential power processing (PDPP) architecture in photovoltaic (PV) systems by replacing two dual active bridge (DAB) converters with a single optimized DAB. This first phase focuses on simplifying the PDPP architecture, reducing hardware redundancy, and improving system cost-effectiveness while maintaining high performance in mitigating mismatch losses among PV strings. The insights gained from this optimization will inform the second phase by adapting the DAB topology. In this phase, the conventional full-bridge design of the DAB will be replaced with a Packed U-Cell (PUC5) converter to meet the bidirectional power flow and high-power density requirements. This unified project bridges renewable energy domains by leveraging the fundamental principles of efficient power processing while addressing the unique challenges of sustainable energy applications. Through detailed real-time simulations or experimental validations and performance evaluations, the thesis will contribute to developing scalable, cost-effective, and high-performance solutions that advance sustainable energy technologies. My thesis aligns closely with my study programme in Sustainable Energy Technology, particularly in Electric Mobility Systems. It integrates key aspects of power engineering, snd energy storage, by focusing on advanced power converter architectures. The academic aspect of my thesis lies in advancing the state of the art in power converter technology through theoretical analysis, real-time simulation, or experimental validation. It contributes to existing knowledge by proposing novel designs—replacing dual DAB converters with a single optimised DAB in PV systems and introducing a new DAB converter using the PUC5 topology. ... Read more

With the rapid growth of Agri-photovoltaic (Agri-PV) systems, a spectral analysis that provides high-resolution data becomes necessary. For such a precise application, there is a need for a spectral irradiance sensor. However, for better precision instruments such as spectroradiometers that are available on the market are expensive. So, in light of this information, the thesis aimed to design and simulate a spectral irradiance sensor’s circuit. The goal was to obtain a PCB design for a high-resolution sensor, suitable for Agri-PV and to simulate the designed circuit to confirm the working theory on which the circuit was made. The circuit was designed on ALTIUM designer where the sensing unit and control unit were separated. The sensing unit consisted: photodiodes and amplifier circuits. The control unit consisted of: ADC and a microcontroller (Raspberry Pi) for signal conditioning and analysis. This circuit was then analyzed and validated through PSPICE OrCAD software. The designed PCB of the Sensing unit contains six photodiodes, which increases the resolution of the spectral sensor. These photodiodes could help in collecting data for a narrow wavelength band (say, approx 10nm width) with the help of bandpass filters. As the PCB was designed while keeping in mind the previous casing’s dimensions of the available PVMD sensor (so the new PCB design can fit on it). Hence, this study finds that it is possible to design a cost-effective spectral sensor circuit that is suitable for Agri-PV applications. ... Read more

As sustainable energy technologies continue to attract growing interest worldwide, comprehending their environmental implications becomes essential. Along with cost optimisation and enhancing efficiencies, it is equally important to reduce a wide range of environmental impacts, which is crucial for attaining global sustainability goals. Silicon Heterojunction (SHJ) solar panels are one such example of a growing sustainable energy technology that are anticipated to take up a considerable share of the global PV market in the coming years, owing to its high achievable efficiency. The goal of this study was to conduct a Life Cycle Assessment on a PV system consisting of Silicon Heterojunction solar cells and modules in order to gain insights for the environmental impacts of such a PV system based on manufacturing in the Netherlands. The study included the production steps of SHJ cells and modules, from raw material to final product and use phase until end of life time. Recyling processes were not included. Inverters and mounting structures were also used to complete the PV system. 4 impact categories were analysed in this study for a rooftop PV system with SHJ cells in 2024. The results for these impact categories were: 22 g CO2-Eq/kWh for Climate Change; 14 g 1.4-DCB-eq/kWh for Ecotoxicity Freshwater; 17.5 g 1.4-DCB-eq/kWh for Ecotoxicity Marine and 0.0016 m2 crop − eq/kWh for Land Use. Similarly, the results for the future scenarios were also reported: Climate change impacts will reduce by more than 10 g CO2-Eq/kWh ; Ecotoxicity impacts will reduce by around 0.6 g 1.4-DCB eq/kWh and land use by 0.0006 m2 crop−eq/kWh over the course of a decade. Then, the contribution analyses were presented for these categories, representing the components and process steps that were major contributors to each of these categories. Finally, two sensitivity analyses were conducted, to see how the environmental impacts change by changing certain parameters. The results gathered in this study, and upon comparing them with the LCA results from earlier published studies showed that the SHJ cell and module manufacturing was more environment friendly than some of the other technologies, along with certain room for improvement. Improving the manufacturing processes and with a change in Dutch electricity mix, in the future scenarios, showed that the environmental impacts will further reduce, making this PV technology highly acceptable and implementable. ... Read more

The goal of this thesis is to analyze the limitations encountered in real-time smart charging during DPMand to integrate them into a smart charging algorithm that schedules EVs. A base case scenario willbe set up to reflect the present dynamics of DPM in a three-phase grid. This scenario will serve as a benchmark for evaluating the smart charging algorithm. The smart charging algorithm itself will employ mixed-integer linear programming (MILP) within a Receding Horizon Optimization (RHO) framework aimed at minimizing charging costs while maintaining a high State of Charge (SOC) for the EVs. To integrate the practical limitations, the grid constraints of a three-phase system will be analyzed and incorporated into the optimization.
Furthermore, a laboratory setup will be constructed to validate the charging behaviors that need to be incorporated into smart charging algorithms and to explore new EV charging behaviors in an experiment. The charging phenomena identified as significant will be integrated into the smart charging algorithm, with a lookup table, to assess their influence on the overall system performance.
The results of this investigation provide valuable insights regarding the charging behaviors and the impact of incorporating these behaviors into a smart charging algorithm. A degradation of the charging efficiency was noted at low charging currents, with the significance of the degradation varying between EV types. Additionally, a voltage discrepancy of the pulse width modulation (PWM) signal of the EVSE was observed, causing an offset between the setpoint of the charging current and the real charging current transmitted by the EVSE.
When these results were incorporated into a smart charging algorithm with a lookup table, clear improvements were seen in the total charged capacity compared to a smart charging algorithm that did not include the lookup table. At a grid capacity of 125 A, the smart charging algorithm with the lookup table provided an increase in charging capacity of 5.23% and an increase of 1.40% for a grid capacity of 175 A. Furthermore, it was observed that the smart charging algorithm with the lookup table could increase the total charged capacity for the low grid capacity of 125 A by 3.97% compared to the charging algorithm that performed immediate charging and DPM.
Both smart charging algorithms, with and without lookup table, show the same reduction in cost compared to the base case algorithm that performs DPM and immediate charging. A decrease in the average charging cost to 4.88% at a grid capacity of 125 A was noted. When the grid capacity is increased, the charging cost could be further decreased to 12.23%, as the increased capacity allows for greater flexibility in scheduling EVs during periods of lowest prices, optimizing the utilization of available power.
... Read more

Aviation is a growing industry responsible for over 2% of the energy-related CO2 emissions in 2021. To achieve the 'Net Zero Emission by 2050 scenario', the aviation industry is turning towards modern propulsion technologies that reduce carbon and NOx emissions. Research is taking place on many prospective aircraft designs, such as hybrid/turbo-electric powertrains, fuel cell/liquid hydrogen-powered aircraft and fully electric aircraft. Although fully electric aircraft offer the cleanest possible air travel, these aircraft are considered the solution for short-haul flights due to the range extension issue caused by the deficient specific energy of batteries compared to currently used aviation fuel. The electric aircraft concept designers rely on the potential development in battery technology while proposing their designs, and sporadic state-of-the-art battery designs are present concerning electric aviation.

The concept of reconfigurable battery packs involves using power switches to modify the arrangement of connected battery cells based on specific requirements. This innovative technique can potentially significantly reduce the weight of battery packs. The primary objective of this thesis was to conduct a comprehensive analysis and comparison between fixed configuration and reconfigurable battery packs in the context of electric aviation. It was imperative first to design these battery packs to facilitate this comparison. Given the limited availability of open data on electric aircraft designs, the power profile was estimated using available reference aircraft specifications and reasonable assumptions. The literature review on power systems in aircraft revealed a significant correlation between system-level voltage and the weight of power cables. This discovery led to estimating an optimal system-level voltage, a critical constraint in battery sizing. For the fixed configuration battery pack, sizing was conducted using both a high-specific energy cell and a high-specific power cell. The design of a reconfigurable battery pack involved strategically leveraging both cell types. This innovative approach created a reconfigurable battery pack capable of dynamically connecting and disconnecting an internal high-specific energy battery pack called the 'primary battery pack' and a high-specific power battery pack known as the 'secondary battery pack' through power switches, allowing them to complement each other during high-power demand phases of flight, such as take-off and climbing.

Software simulations were conducted for the validation of this technique. These simulations revealed that the reconfigurable battery pack experienced higher C-rates than the fixed configuration battery pack. Given that higher C-rates can impact battery health by inducing capacity loss over multiple cycles, a preliminary ageing analysis was performed to quantitatively assess the adverse effects of higher C-rates on the reconfigurable battery pack.

The results quantified that around 400 kg of potential weight savings is possible by employing reconfigurable battery packs over fixed configuration battery packs at only 0.4% more capacity loss over 500 charging-discharging cycles. The weight savings can be translated into three different scenarios. Firstly, payload weight capacity can be enhanced. Secondly, flying with lesser weight will offset the power profile, saving energy. Lastly, an additional number of cells equivalent to the mass saved can realise the range extension of the electric aircraft.
... Read more

This report emphasizes the importance of implementing quality control methods in the production machines at HyET Solar for assessing the quality of deposited materials. The focus is on two key steps: the deposition of the front transparent conductive oxide (TCO) layer and the deposition of silicon layers. Models were developed to characterize the quality of the TCO layer, including layer thickness, carrier concentration, and mobility of the electrons. A Drude model-based approach was chosen for in-line implementation. The sheet resistance of the TCO layer was measured using an improved tool, by enhancing its robustness and accuracy. To assess the quality of the deposited silicon layers, a non-contacting capacitive device was developed and calibrated (to measure the spatial gap between the photovoltaic layer and the device). Results showed that the Drude model fitting provided sensible results for carrier concentration and mobility with the former having a better correlation than the latter, with the standard Hall effect measurements. The results from the optical thickness model showed overestimation of values as compared to the scanning electron microscopy (SEM) results. The electrical sheet resistance values correlated well with Hall effect measurements than the optically obtained sheet resistance values. The calibrated non-contacting capacitive device demonstrated its ability to measure opto-electrical properties of the silicon layers, accurately. This research contributes to enhancing the efficiency and reliability of roll-to-roll production process of thin-film solar modules. ... Read more

Thin-film silicon technology creates electricity out of micrometer thick silicon absorber layers, which makes this technology less material heavy compared to classic crystalline technology. This advantage can be further exploited with the transition towards flexible thin-film technology, where the non-modular cost can be further reduced compared to traditional crystalline solar parks ect. However, thin films have limited absorption coefficients at higher wavelengths which means the optical pathlength must be maximised to overcome this limitation. In literature, the highest efficiencies are obtained with the creation of periodic textures resulting in 10.2%, 12.7% or 14% for nanocrystalline, micromorph and triple junction silicon technology. All these cells are made on silicon substrates which means the back of the cell is textured but if the front side of the solar cell is textured, efficiencies can outperform the current holding records. A methodology is designed to create periodic micro-textures on Corning glass to improve the total absorption of lower energetic wavelengths. However, the creation of random micro-textures (Aluminum Zinc oxideand Indium Tin Oxide sacrificial texturing)(AZO-/ ITO textures) is also researched because different methodologies exist and limited knowledge exists on which methodology results in the highest amount of scattering. Second, a comparison between random and periodic textures must be made. Both types of textures undergo optical- and physical parametrisation after which both aspects are correlated to each other to gain a deeper understanding of light management. For random textures, Haze-values between 93-86% are obtained. These high values are obtained because the created craters are characterised by an increased depth for identical crater widths. Second, each methodology has its characteristic depth-width ratio which explains the optical superiority of one (ITO textures). For periodic textures, Haze-values lie between 50-3% with a maximum obtained aspect ratio of 0.18 but the optical response is not comparable to random textures because diffraction is the dominant light management technique. Therefore Angular Intensity Distribution measurements must be performed, which resulted in the conclusion that the created ITO textures stay superior (also compared to literature) while the AZO textures have a similar performance compared to the periodic texture. This translates itself in a superior external quantum efficiency (EQE) of ITO from 800nm on. Between 600-800nm, the periodic textures are superior. ... Read more

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.
... Read more

Climate change and global warming effect is currently one of the main threats that humanity is facing. The significant increase of greenhouse gas emissions since industrialisation has contributed to the global warming and therefore, the use of sustainable energy sources with zero greenhouse gas emissions has emerged as an urgent priority. Photovoltaic modules have become one of the world’s leading methods of generating electricity using solar energy. The share of solar PV electricity generation has significantly increased in the last decade and is expected to keep rising in the following years. However, the land area cost required for the development of photovoltaic solar systems is very high and it is therefore of foremost importance to increase the energy yield per unit area of PV modules. This is achieved using bifacial PV modules which make use of the irradiance incident on both sides of
the module leading to higher energy generation. This, combined with the prediction that bifacial modules will dominate the market in less than 6 years, a parameter used for the evaluation of PV modules performance in different climates needs to be defined namely ”energy rating”.
Energy ratings have been developed only for monofacial modules as described in IEC61853 standard and this work focuses on the extension of this standard to bifacial modules. For the calculation of the energy rating the energy yield and the irradiance incidence on both faces of the module have to be obtained. For this reason, an irradiance model is developed in MATLAB to calculate the irradiance on the rear side of the module using the data given in the standard IEC61853. Note that the front side irradiance is available in the existing data and as a result no further calculations for the front side of the module are required. The irradiance on the rear side of the module is obtained using 2D view factors taking into consideration the shading of the ground which can substantially affect the results. Also, the effect of the elevation of the module from the ground surface is examined and found that at sufficient height (≥ 1푚) the impact of ground clearance on the rear side irradiance is minimised. Finally, the ground reflected irradiance is obtained using the spectral reflectivity of different ground materials where it is shown that the use of improper albedo values can lead to inaccurate results.
The next step is the calculation of the energy yield of the bifacial module. For this, a similar methodology used to obtain the energy yield of monofacial modules in the standard IEC61853 is used. More specifically, the incident irradiance on the rear side of the module is corrected for the angle of incidence and spectrum effects to generate similar conditions as in the STC. Additionally, the operating module temperature is obtained and using the total irradiance on the front and the rear side of the module the energy yield is calculated. Finally, the energy rating of bifacial modules is determined using two different approaches. In the first approach, CSER of bifacial modules is obtained using the energy yield and the total irradiance on bifacial modules. This approach results in lower energy rating than unity but needs re-scaling of the monofacial module energy rating compared to the standard. The second approach use the energy generated from both sides of the module but only the irradiation on the front side of the module is taken into account leading to CSER values higher than one, while the energy rating of monofacial modules as obtained in the standard is used. In both approaches the energy rating of bifacial modules found to be up to 17% higher than that of monofacial depending on the bifaciality of the module and the climate conditions.
The developed model is validated using real outdoor measurements for a system located in Weurt, Eastern Netherlands. First, the in-plane irradiance on both sides of the module is obtained from the model and then, the simulated energy yield is calculated and compared to the measured energy yield of bifacial modules. The results show a small difference between the simulated and measured energy yield for the time period between October 2019 and June 2020 with a total variation of 4.65% in the total energy yield. ... Read more

Renewable energy sources such as solar and wind energy rely on climate­ and weather conditions, like sun irradiation in the case of solar energy, and wind speed in the case of wind energy. These change throughout the day and with the seasons. There are periods of little wind, and during the night there is no sunlight. During periods of no sunlight and little to no wind, there is still a demand for energy. This leads to a shortage of energy. On the other hand, there are periods when the amount of available wind­ and solar energy will surpass the demand for energy, leading to an energy excess. To mitigate this mismatch between energy production and energy demand the excess energy can be stored to be used during periods of shortage. Many different solutions for this have been investigated in recent years. One of the storage technologies that is currently quite dominant is battery storage. Lithium-ion batteries are used quite widely, among others in battery electric vehicles. However, the use of batteries as a storage device to overcome energy mismatch is not yet implemented on a large scale, as most battery technologies are still quite novel, making them
uneconomical for this use compared to traditional hydrocarbon fired power plants. Furthermore, many battery technologies depend on scarce and expensive minerals. Recently, a battery utilizing silicon as its anode and oxygen from the air at the cathode has been proposed. This so­called silicon­-air battery utilizes mainly silicon and oxygen, which are the two most common elements on earth. Furthermore, the theoretical energy density of this battery type was shown to be significantly higher than the energy density of lithium­-ion batteries. Because of this, the silicon­-air battery has been a growing area of research in the last years.

Battery models help to simulate batteries based on empirical data and electrochemical systems. These models are a powerful tool in the evaluation of the performance of batteries. Parameters of the battery can be altered quickly and specifically. This can provide a powerful analysis tool to determine weaknesses in a batteries. They can also help in further developing an understanding of the operating principles of the battery technology. A specific type of model is the finite element model. In this type of model the object that is modeled is divided into small pieces and for each piece a set of (partial) differential equations is evaluated. Different electrochemical, chemical, physical and mathematical models can be modelled and combined in this tool. For this thesis a finite element model of an alkaline silicon­-air battery is developed in COMSOL. The model is based on an earlier model that was developed in 2020.

Besides the discharge mechanism, alkaline silicon-­air batteries are subject to two secondary reactions that hinder the performance of the battery: corrosion and passivation. Corrosion consumes a large part of the silicon without contributing to the discharge. Passivation creates an oxide layer on the surface of the silicon electrode, stopping the discharge reaction. Both these reactions have been implemented in the model. Besides that, a metal contact on the silicon anode is implemented in the model. The parameters used in this model are supported by empirical values for these parameters. Finally, the model was compared to experimental results.

The simulation of the discharge of the alkaline silicon­air battery was improved in several ways compared to the pre-­existing model. The corrosion was shown in the simulations, although the mechanism is somewhat simplified because of the 1D nature of the model. The passivation reaction was shown in the simulations as well, and was improved on compared to the previous model by breaking it up into two steps. Using this model, experimentally observed trends could be simulated reasonably well. The simulated discharge potential was a close representation of the experimental data, although the open circuit potential was somewhat higher, and for higher current densities the potential was somewhat lower. For different electrolyte concentrations the model showed results similar to what was found in experiments. ... Read more