With an increase in higher power (ultra) fast EV charging stations and a new EU law for mandatory deployments of EV charging stations, an optimal MVAC grid connection for these charging stations is desired. Considering this connection, the use of a solid-state transformer (SST) performs better in terms of weight, size and efficiency with a similar cost, compared to the conventional low-frequency transformer (LFT) for MVAC to LVDC conversions. This study compares three MMC-based SST topologies where a DAB is connected to each submodule: Double-Star, Single-Star and Single-Delta. The cost of an MMC mainly depends upon the required energy storage and the switch stress. The topologies are therefore mainly compared based on these parameters, but other parameters are considered as well. With the goal of minimising the required energy storage, an 80% MMC energy storage reduction compared to the theoretical minimum requirement has been achieved by control.

A novel mathematical model has been proposed for each SST; this uses an MMC model based on the switching function and a DAB model based on the single phase-shift control. The model has been implemented in simulation and proven to accurately determine the average behaviour of the SST while significantly reducing the simulation complexity and time. This model helps to understand the SST's behaviour and furthermore allows for control system tuning both manually and automatically using the Genetic Algorithm.

Three different control systems have been designed. Control system A, where the MMC current is controlled by the average submodule voltage and the DAB controls the LVDC bus voltage. Control system B, where the DAB controls each individual submodule voltage and the MMC current is controlled by the LVDC bus voltage. Control system C, which is similar to control system B, but uses a stable DC voltage source on the LVDC bus and a set MMC current. An improved DAB control has been designed for control systems B and C, resulting in control systems B* and C*. This control is based on the use of a current feedforward and a PI controller combined with the inverted equations of the DAB model. The three topologies have been successfully simulated with this improved DAB control system using an 80% MMC energy storage reduction compared to the theoretical minimum requirement. This improves the general behaviour and significantly reduces the cost of the SST. The improved DAB control system has been tested using a hardware DAB with a current step input, which has shown that the new control system performs better in voltage peak reduction compared to PI control.

Out of the three topologies, the Single-Star topology performs the best. It has the lowest energy storage requirement and switch stress. Furthermore, its behaviour lies the closest to the ideal model. The best result for the Single-Star SST is achieved with the proposed improved DAB control, which leads to the lowest energy storage requirement, switch stress, THD, submodule voltage deviations and settling time. Out of these two control systems, C* performs the best.

Photovoltaic (PV) systems are often exposed to mismatch conditions caused by partial shading, different mounting angles, dust accumulation, cell degradation, etc. Among various techniques, PV to Virtual Bus Parallel Differential Power Processing (PV2VB P-DPP) has been proposed to overcome the mismatch among PV strings. This thesis focuses on the dynamic behavior of the PV2VB P-DPP configuration in order to analyze the system stability and design appropriate controllers. Configuration needs to control two different types of converters: 1- P-DPP converters (inner control loop) and 2- the Central Converter (outer control loop). Moreover, since the selection of capacitance for the virtual bus is a tradeoff between several factors, such as cost, stability, reliability, current ripple, and so on, this thesis provides a methodology to identify an acceptable range for the capacitance of the virtual bus.
This project used the state space representation to model the system owing to its simplicity and ability to provide a uniform and convenient starting point for linearization, stability evaluation, control design, and simulation. Since the system’s large signal model is nonlinear and difficult to work with, we linearized the state space equations (to achieve the small-signal model of a PV2VB P-DPP system consisting of any number of strings and converted them into the Laplace form to perform system analysis and controller design. Considering Gain and Phase Margin as the main design criteria, proportional control (Kp ) and integral control (Ki) were tuned for PI controllers using the SISO tool MATLAB toolbox for a PV system consisting of two PV strings. The system stability depends on two main aspects: the value of the virtual bus capacitor (CVB) and the voltage magnitude in the virtual bus (vV B ). The complete developed model has been implemented in MATLAB.
For the simulated PV2VB P-DPP system, a gain margin of 15.7 dB, a phase margin of 121 degrees, and a settling time of 0.8 s have been achieved for the outer control loop (central converter) by setting Ki and Kp to 5s^−1 and 0.5, respectively. On top of that, a gain margin of infinity dB, a phase margin of 91.2 degrees, and a settling time of 1 ms have been achieved for the inner control loop (DPP converter) by setting Ki and Kp to 10s^−1 and 0.1, respectively. Finally, it is shown that the virtual bus capacitor should be selected within the range 50µF- 5mF in order to make the system have higher stability margin. However, the final selected value of capacitance for the virtual bus is equal to 1.2 mF owing to other constraints, such as the expected ripple current.

Kelp Blue is a company whose top priority is the well-being of the planet. Through the cultivation of giant kelp on offshore farms, they create several sustainable products, new job opportunities in regions where they are needed, enhance biodiversity in the water, and above all, sequester tons of CO2 from the air. The start-up is still in its research and development phase, but plans to be building farms on a large scale in just a few years. Despite their knowledge in engineering, the company still needs consulting on certain elements. Therefore the company invited a group of students from the Delft University of Technology to Lüderitz, Namibia for a consultancy project. The project involved creating a procedure for the company to scale up in a sustainable manner. The students decided that this complex problem should be divided into sub-problems. One workstream focused on reducing the carbon emissions during upscaling, while the other workstream focused on analyzing and improving the company’s current design and installation of the farms. Following, both parts of the project are shortly summarized: Part I: Improving the company’s current design Kelp Blue is currently in the pilot phase, in which they’re installing their first large giant kelp farms. Before, they were focusing on the complete installation, including planting the kelp on the submerged netting structure, and the review of this. For the company’s commercial phase, where they want to be able to place farms daily on a large scale, designs were still developed and analyzed. For the commercial phase, this workstream made a new design and installation method. It required an installation where buoys would need to be submerged, the structure locked in place at the desired depth, without the use of scuba divers or remote operated vehicles. Despite the fact that these requirements were challenging, an outstanding result was achieved. The main problem was divided into subproblems, and for each of those a suitable solution was created. Hopes are that the company will consider the given advice as helpful and maybe implement some parts of (or the whole) new design. Part II: Reducing carbon emissions during upscaling First, interviews and desk research were conducted to get a good idea of the challenge of sustainability. This included reading reports, speaking with employees, policy makers and experts with experience within the area. With this information, the challenge could be mapped out and the solution space became clear in terms of legislation and technical possibilities. Climate information was also requested that could later be used to run simulations. During the determination of the possible solutions, research was done on the realistic possibilities, where eventually the use of either solar or wind energy was most appropriate. After conducting a multi-criteria analysis that was put together with the management of Kelp Blue, investing in a solar plant proved to be the most appropriate solution.

As PV capacity in urban areas keeps increasing, non-uniform illumination of panels will become more prevalent. This could cause the partial shading to become more frequent, reducing PV system performance. Some ways to solve this problem is by the use of module-level maximum power point tracking (MPPT), micro inverters, or reconfigurable modules. To this end, the integration of metal-oxidesemiconductor field-effect transistor (MOSFET) on solar cells could play an important role in future methods to prevent this issue. This integration of a MOSFET allows for module level, and potentially sub-module level, MPPT, as well as the application of reconfigurable modules to circumvent this issue. This thesis aims to optimize the MOSFET dimensions and fabrication process to be able to handle the short circuit current and open circuit voltage of a PV module, and to analyze the optoelectrical effects under direct illumination of the MOSFET performance. In this thesis report, a flowchart is proposed on how to fabricate a working power MOSFET while combining the fabrication techniques used in the Integrated Circuits and Photovoltaics industries. This process closely resembles the fabrication of solar cells and uses similar techniques used to fabricate interdigitated back contacted (IBC) solar cells. It is shown that It is shown that the use of wider devices can reduce channel resistance from 167Ω for a PMOS device with a width of 500𝜇m down to 20Ω for a device with a width of 5000𝜇m. For NMOS devices a similar relationship can be seen where the channel resistance is 49Ω for a width of 500𝜇m and 8.1Ω for a device width of 5000𝜇m. The current density of the devices drop from 115𝜇𝐴/𝜇𝑚 for an NMOS device with a width of 500𝜇m to less than 80𝜇𝐴/𝜇𝑚 for a 5000𝜇m wide device. For PMOS this density drop is smaller where the drop is from 33𝜇𝐴/𝜇𝑚 to 27𝜇𝐴/𝜇𝑚. A study on the effects of implantation energy and scattering layer thicknesses showed that both lower energies and thicker layers yield higher drain currents and lower channel resistance. A possible explanation for this is that a shift in the threshold voltage increased the overdrive voltage and therefore the drain current. In the investigation of the effects of direct illumination on the electrical characteristics of the device it was found that the threshold voltage increases for PMOS devices from -0.21V under no illumination to -0.06V under full spectrum illumination at 1000𝑊/𝑚2 and decreases for NMOS devices from 0.06V under no illumination to -0.15V under full spectrum illumination at 1000𝑊/𝑚2. Furthermore the off state gate leakage current increases by factor 33 under illumination at 1000𝑊/𝑚2 for NMOS devices and by a factor of 107 for PMOS devices. The electron mobility of the NMOS transistor increases with incident light, improving the drain current gate voltage relationship. The channel resistance for the NMOS devices improved between 5-13%, depending on the intensity of the illumination, while the channel resistance of the PMOS increases up to 2%.A similar effect for the hole mobility of the PMOS was not observed. Similarly, the channel resistance of the NMOS transistor improved, possibly due to the shift in threshold voltage or improved electron mobility. This improvement in performance was not recognized for PMOS transistors, however. A flowchart has been proposed for a process in which a MOSFET is fabricated on the backside of an Interdigitated Back Contacted (IBC) solar cell while combining as many steps as possible from their respective flowcharts to reduce complexity and costs, possibly leading the best balance between MOSFET and IBC fabrication.As PV capacity in urban areas keeps increasing, non-uniform illumination of panels will become more prevalent. This could cause the partial shading to become more frequent, reducing PV system performance. Some ways to solve this problem is by the use of module-level maximum power point tracking (MPPT), micro inverters, or reconfigurable modules. To this end, the integration of metal-oxidesemiconductor field-effect transistor (MOSFET) on solar cells could play an important role in future methods to prevent this issue. This integration of a MOSFET allows for module level, and potentially sub-module level, MPPT, as well as the application of reconfigurable modules to circumvent this issue. This thesis aims to optimize the MOSFET dimensions and fabrication process to be able to handle the short circuit current and open circuit voltage of a PV module, and to analyze the optoelectrical effects under direct illumination of the MOSFET performance. In this thesis report, a flowchart is proposed on how to fabricate a working power MOSFET while combining the fabrication techniques used in the Integrated Circuits and Photovoltaics industries. This process closely resembles the fabrication of solar cells and uses similar techniques used to fabricate interdigitated back contacted (IBC) solar cells. It is shown that It is shown that the use of wider devices can reduce channel resistance from 167Ω for a PMOS device with a width of 500𝜇m down to 20Ω for a device with a width of 5000𝜇m. For NMOS devices a similar relationship can be seen where the channel resistance is 49Ω for a width of 500𝜇m and 8.1Ω for a device width of 5000𝜇m. The current density of the devices drop from 115𝜇𝐴/𝜇𝑚 for an NMOS device with a width of 500𝜇m to less than 80𝜇𝐴/𝜇𝑚 for a 5000𝜇m wide device. For PMOS this density drop is smaller where the drop is from 33𝜇𝐴/𝜇𝑚 to 27𝜇𝐴/𝜇𝑚. A study on the effects of implantation energy and scattering layer thicknesses showed that both lower energies and thicker layers yield higher drain currents and lower channel resistance. A possible explanation for this is that a shift in the threshold voltage increased the overdrive voltage and therefore the drain current. In the investigation of the effects of direct illumination on the electrical characteristics of the device it was found that the threshold voltage increases for PMOS devices from -0.21V under no illumination to -0.06V under full spectrum illumination at 1000𝑊/𝑚2 and decreases for NMOS devices from 0.06V under no illumination to -0.15V under full spectrum illumination at 1000𝑊/𝑚2. Furthermore the off state gate leakage current increases by factor 33 under illumination at 1000𝑊/𝑚2 for NMOS devices and by a factor of 107 for PMOS devices. The electron mobility of the NMOS transistor increases with incident light, improving the drain current gate voltage relationship. The channel resistance for the NMOS devices improved between 5-13%, depending on the intensity of the illumination, while the channel resistance of the PMOS increases up to 2%.A similar effect for the hole mobility of the PMOS was not observed. Similarly, the channel resistance of the NMOS transistor improved, possibly due to the shift in threshold voltage or improved electron mobility. This improvement in performance was not recognized for PMOS transistors, however. A flowchart has been proposed for a process in which a MOSFET is fabricated on the backside of an Interdigitated Back Contacted (IBC) solar cell while combining as many steps as possible from their respective flowcharts to reduce complexity and costs, possibly leading the best balance between MOSFET and IBC fabrication. As PV capacity in urban areaskeeps increasing, non-uniform illumination of panels will become more prevalent.This could cause the partial shading to become more frequent, reducing PVsystem performance. Some ways to solve this problem is by the use ofmodule-level maximum power point tracking (MPPT), micro inverters, orreconfigurable modules. To this end, the integration ofmetal-oxidesemiconductor field-effect transistor (MOSFET) on solar cells couldplay an important role in future methods to prevent this issue. Thisintegration of a MOSFET allows for module level, and potentially sub-modulelevel, MPPT, as well as the application of reconfigurable modules to circumventthis issue. This thesis aims to optimize the MOSFET dimensions and fabricationprocess to be able to handle the short circuit current and open circuit voltageof a PV module, and to analyze the optoelectrical effects under directillumination of the MOSFET performance. In this thesis report, a flowchart isproposed on how to fabricate a working power MOSFET while combining thefabrication techniques used in the Integrated Circuits and Photovoltaicsindustries. This process closely resembles the fabrication of solar cells anduses similar techniques used to fabricate interdigitated back contacted (IBC)solar cells. It is shown that It is shown that the use of wider devices canreduce channel resistance from 167Ω for a PMOS device with a width of 500𝜇m down to 20Ω for a devicewith a width of 5000𝜇m.For NMOS devices a similar relationship can be seen where the channelresistance is 49Ω for a width of 500𝜇mand 8.1Ω for a device width of 5000𝜇m.The current density of the devices drop from 115𝜇𝐴/𝜇𝑚 for an NMOSdevice with a width of 500𝜇mto less than 80𝜇𝐴/𝜇𝑚 for a 5000𝜇m wide device. For PMOSthis density drop is smaller where the drop is from 33𝜇𝐴/𝜇𝑚 to 27𝜇𝐴/𝜇𝑚. A study on theeffects of implantation energy and scattering layer thicknesses showed thatboth lower energies and thicker layers yield higher drain currents and lowerchannel resistance. A possible explanation for this is that a shift in thethreshold voltage increased the overdrive voltage and therefore the draincurrent. In the investigation of the effects of direct illumination on theelectrical characteristics of the device it was found that the thresholdvoltage increases for PMOS devices from -0.21V under no illumination to -0.06Vunder full spectrum illumination at 1000𝑊/𝑚2 and decreases for NMOSdevices from 0.06V under no illumination to -0.15V under full spectrumillumination at 1000𝑊/𝑚2. Furthermore the off stategate leakage current increases by factor 33 under illumination at 1000𝑊/𝑚2 for NMOS devices and bya factor of 107 for PMOS devices. The electron mobility of the NMOS transistorincreases with incident light, improving the drain current gate voltagerelationship. The channel resistance for the NMOS devices improved between5-13%, depending on the intensity of the illumination, while the channelresistance of the PMOS increases up to 2%.A similar effect for the hole mobilityof the PMOS was not observed. Similarly, the channel resistance of the NMOStransistor improved, possibly due to the shift in threshold voltage or improvedelectron mobility. This improvement in performance was not recognized for PMOStransistors, however. A flowchart has been proposed for a process in which aMOSFET is fabricated on the backside of an Interdigitated Back Contacted (IBC)solar cell while combining as many steps as possible from their respectiveflowcharts to reduce complexity and costs, possibly leading the best balancebetween MOSFET and IBC fabrication.    

Increasing concerns surrounding the influence of urban climate on the livability of cities and the health of citizens lead to a need for environmental data on a more localized scale. Self-powered weather stations that use the many WiFi networks spanning the city to transmit their data are a promising solution to increase the amount of data on localized urban climate. Conventional weather stations often measure wind, rain and sun radiance, phenomena that are heavily influenced by the many objects present in an urban environment, which is why they are usually placed outside of the city or on top of buildings. Self-powered weather stations placed on street level can be used to gather data on temperature, humidity, air pollution and noise pollution. If a good trade-off is made between the sensing capacities, the battery capacity and the solar panel size, a weather station like this can do frequent measurements throughout the year, surviving the winter months of low solar panel power generation due to reduced irradiation. In the simulations done for this project, it was found that a simple algorithm that linearly varies the relative measuring frequency of the most power-hungry sensors with the available battery charge greatly improved the average measuring frequency and lifetime of the weather station. Thanks to the increased power budget, additional sensors can be added, such as gas sensors. Furthermore, the weather station can be made more compact and affordable by reducing the size of the solar panel and/or the battery capacity of the weather station.

The on-field performance and lifespan of PV modules are affected by the interaction of numerous parameters, among which temperature, strain, and humidity. Among these parameters, only temperature is occasionally measured in PV installations, and such monitoring is often external to the module. This limits its use and does not provide accurate information on the conditions at cell level. The integration of different sensors on PV cells can improve the performance of PV devices and enable the early detection of faults and unwanted operating conditions, examples of which are PV-module delamination and the occurrence of hotspots, respectively. This thesis reports on the design, fabrication and testing of four types of sensors, as an initial step within the PVMD group towards sensor integration on PV cells. The devices considered for this work are the following: an aluminum-based resistive temperature sensor, a Boron-doped poly-silicon piezoresistive strain sensor, and two polyimide-functionalized humidity sensors – one capacitive, the other thermoresistive. Furthermore, these devices are combined into multi-sensing platforms with the aim to simultaneously sense sets of parameters (e.g., strain & temperature) to eventually compensate for their reciprocal interference. The results of the electrothermal characterization of the non-laminated temperature and strain sensors reveal an overall linear response of the devices, with an average TCR of around +3.75*10-3 °C-1 and -3.7*10-3 °C-1, respectively; this translates into a change in resistance of approximately 22.2-22.5% over the temperature range under study (30 °C-90 °C). Meanwhile, the characterization with a climate chamber of a fabricated capacitive humidity sensor shows a significant increase in capacitance: when relative humidity changes between 20% and 80% at 30 °C, the measured capacitance rises from 6.86 nF to 7.20 nF – equivalent to a 5% increase. Furthermore, capacitance measurements performed at constant humidity ratio and varying temperatures indicate a substantial cross-sensitivity of the humidity sensor under test, resulting in an approximately linear capacitance increase between 20 °C and 40 °C with an average regression slope of 10 pF/°C. Since the tested capacitive humidity sensor and piezoresistive strain sensor show a substantial response to temperature, temperature compensation is needed to ensure reliable and accurate measurements of both humidity and strain. To this regard, a simplified compensation based on the simultaneous interrogation of the resistive temperature sensor and capacitive humidity sensor is successfully performed, which highlights the importance of integrated multi-sensing platforms.

Due to the current trend of urbanization more people will come and live in cities than ever before. This increases the need to monitor the urban environment, to be able to improve the living conditions of the urban dwellers. Our project combines the need to monitor the local environment, with a portable, self-powered and wireless weather station. The final design consists of a solar powered and WiFi-connected weather station with autonomous functionality for one year. For our research, the focus was on the Netherlands. Part of such a project is the power management which will be dealt with in this thesis.
In the thesis, different maximum power point tracking algorithms will be discussed and compared. Furthermore, some more research is done in the hardware design, the use of different evaluation boards and battery configurations. Finally, a prototype using the incremental conductance algorithm is constructed and tested. Simulations lead to an efficiency of around 80%, which means autonomous functionality for a minimum of one year. The physical system had a lower efficiency, but autonomous functionality for one year was still achieved.

Individual actions cannot solve the current climate crisis. Part of the collective effort is to research solar energy as new ways to produce cleaner, cheaper and more efficient electricity. Among all the current solar cell technologies, a thriving and promising one is perovskite as an absorber material. In the last ten years, the power conversion efficiency evolved with a steep rhythm. In 2019, a maximum of 25.2% in a single junction configuration was reported, while more actual research proves that using them as a tandem can reach up to 30%. Perovskites have the advantage of changing their bandgap by ion-­mixing, from as low as 1.2 eV to even higher than 2.5 eV. Besides, it is flexible, translucent and has similar efficiencies to c­-Si; while being cheaper and easier to produce. It is expected that it will replace c­-Si-­based solar cells in the long run and significantly reduce the price of solar energy.

This project is developed under the Photovoltaic Materials and Devices (PVMD) section of TU Delft, in conjunction with HyET Solar and Flamingo PV. The software ASA and GenPro4 were used to validate single-­junction solar cells and optimize tandem devices. The goal of this thesis is aligned to HyET’s ob­jective: improve its flexible thin-­film solar cell by increasing the power conversion efficiency above 12%.

To carry out the validation and calibration of the single­-junction references, first, a study of all the possible perovskite­-based solar cells was performed. The chosen perovskites have a Methylamonium and Formamidinium combination. The first one has a bandgap of 1.55 eV and works as a high bandgap
absorber material (K0.05(FA0.85MA0.15)0.95Pb(I0.85Br0.15)3), while the low bandgap corresponds to 1.25 eV ((FASnI3)0.6(MAPbI3)0.4) [20]. By adjusting some of the absorber layers’ electrical parame­ters, the references’ electrical properties were matched.

Once validated, the respective p­i­n junctions of the perovskite solar cells were introduced into HyET’s solar cell architecture. By doing this, it is already possible to see the advantages of using per­ovskites as absorber materials: the power conversion efficiency grew from 7.71% to 18% and 19.45% for the high and low bandgap cells. Besides, there is also a better use of the light spectrum. Cali­brating a tandem solar cell is much more complicated. That is why it is done first on the individual single-­junction solar cells, and afterwards, both are stacked together.

The first step to optimize a tandem device is to do an optical simulation (GenPro4). By analyzing the absorptance of the tandem device and the optical current of the top and bottom absorber materials, it is possible to obtain the best combination for the current matching of the tandem solar cell. By modifying
both of the absorber materials’ thicknesses, the optical current mismatch can be reduced. As a result: 300 nm and 600 nm thickness for the a­-Si / LBG perovskite tandem, and 120 nm and 1700 nm for the HBG perovskite / nc-­Si; achieving a mismatch below 0.04 mA/cm2 and 0.2 mA/cm2 correspondingly.

The second step in optimizing a tandem device involves an electrical simulation (ASA). The optimization is related to facilitating tunneling recombination at the n­-p junction by adjusting the doping of these layers. The optimized tandem solar cells have the following electrical properties: 1.56 V, 14.54 mA/cm2, 0.85 and 19.69% for fill factor and PCE for the HBG perovskite / nc-­Si tandem solar cell; while 1.55 V, 11.13 mA/cm2, 0.72 and 12.36% for fill factor and PCE of the other. With these results, it is plausible to confirm that HyET’s objective of having thin-­film flexible solar cells with a PCE above 12% can be met by using perovskite technology in their production line.

Thin-film flexible solar panels can be utilized on many surfaces where conventional solar panels are hard to be used such as side walls of buildings, ship roofs or curved surfaces. In conventional solar cells, glass is used to protect the panels from external damage. However due to its heavy weight and rigidity, glass is not an option for thin-film flexible solar cells. HyET Solar, a company based in the Netherlands that produces flexible thin-film solar cells uses a transparent foil produced using a roll-to-roll process to encapsulate and protect their solar panels. In order to reduce the amount of materials used and cut the costs, a thinner foil is being developed. Producing the thinner foil in a roll-to-roll process causes different defects in the foil, among which half sinusoidal waves forming mostly in the bottom side of the foil, these waves are called wrinkles. The process of manufacturing the top encapsulant layer involves changing temperatures and mechanical stresses applied on the foil. Therefore, two models were developed to understand the effect of three process parameters (web force, web speed and temperatures of each production zone) on wrinkle formation. First, a thermal model of the process using ANSYS program was developed to understand the temperature profile of the produced foil along the process. Then, a mechanical model that uses the output of the thermal model and the applied mechanical forces to study the effect of the investigated production parameters on wrinkle formation was worked out. The results show that operating at higher temperatures and reducing the thickness of the foil are directly responsible for decreasing the threshold of the critical stress that causes wrinkle formation and thus reducing the range and the magnitude of the force to 1.4 N is needed to perform the process without forming wrinkles in the foil. Varying web speed between 0.3 m/min and 3m/min is found to have a minor effect when varied under high temperatures. Finally, decreasing the temperature of the first and second zones by 10 °C is found to extend the range of the web force that can be applied. Performing the process under lower temperatures or reducing the mechanical forces that act on the foil will reduce wrinkle formation in the developed foil; web speed should not be considered in mitigating wrinkle formation.

With the rise of various renewable energy sources, comes the possibility for combining the different type of sources together to balance their shortcomings. The goal is to find a renewable energy system that can be reliable year-round and be accessible for everyone. This research tries to model such a system. A model of a grid-tied PV-battery-electrolyser-fuel cell power system, which is based on a continuation of a series of master thesis projects, was expanded to include a neighbourhood with a fully electrical load or a combination of electrical and hydrogen loads. This model was developed to answer the following question. What is the techno-economic feasibility of a grid-tied PV-battery-electrolyser-fuel cell power system for a household area in the Netherlands which is either fully electrical or hydrogen integrated? This hybrid system is simulated by using the graphical interface program TRNSYS. The system size of the PV, batteries, electrolyser, fuel cell and hydrogen gas storage tank are optimised by the GenOpt, an add-on for TRNSYS. The optimisation algorithm will try to find the lowest levelised cost of energy(LCOE) while keeping the system self-sufficiency ratio(SSR) around 1 [%]. This will mean that only 1 [%] of the load is allowed to be extracted from the grid. The simulation is based on a neighbourhood that consists of 630 houses located in Pijnacker Netherlands. All houses will be equipped with a roof mounted solar PV system with centralised batteries, electrolyser, fuel cell and a hydrogen storage tank. If needed the model can be extended to include a small solar park next to the neighbourhood. The model will simulate two scenarios for a simulation time of one year, the first being that the neighbourhood is fully electrical and the second for a neighbourhood with integrated hydrogen gas in its consumption. The first one is the base, with only the electrical load demand of houses. Then the load profile will be extended by adding vehicle to the neighbourhood, including the heat demand of the house. These additional load profiles will either be electrical energy based for the fully electrical scenario or hydrogen gas based for the integrated hydrogen scenario. To estimate the economic development of this hybrid system, a price projection of PV, battery, electrolyser, fuel cell, hydrogen heating, heat pumps and inverters components were determined for the years 2020, 2030, 2040 and 2050. a, the cases will all be simulated for these years. The economic analysis will be over the systems lifetime, which is 25 years. Before the cases were simulated the model undertook a sensitivity analysis. From this resulted that the simulation start time can be moved from the 1st of January to the 2nd of March to relief the storage tank of getting depleted at the start of the simulation. A battery discharge constraint was lifted and this led the batteries to provide more energy. A forecasting method was applied to the system that effectively reduced the electrolyser on/off cycles by 60 [%], which increased the lifetime of the electrolyser component. From a technical feasibility analysis of the cases, it resulted that the integrated hydrogen scenario was not technical feasible with the PV system (roof mounted with the PV park) of this model. All the integrated hydrogen scenario cases resulted in a depleted hydrogen storage tank, which forced the system to buy the hydrogen demand externally. The system will rely on an external source more than the allowed 1 [%] (hydrogen gas SSR >> 1 [%]) of the load demand. From the fully electrical scenario the 2020 C-E-(V+H) case resulted not be technical feasible with a SSR value of 2.1 [%]. All the other cases were technical feasible. From an economic and cost perspective, the cases resulted that the LCOE reduced with the years. The lowest LCOE value found was for the C-E-(Base) case, which reduced from 0.44 [€/KWh] in 2020 to 0.21[€/KWh] in 2050. The cost breakdown of the cases resulted in the PV system and the storage tank to be the most expensive components of this system. Due to the fact that the C-H2-(H) case had to buy a significant amount of hydrogen from an external source, this became a significant expensive cost of the system. Comparing the two scenarios resulted that the integrated hydrogen scenario system sizes were smaller, but this is an effect of the system being more eager to buy hydrogen gas then to expand the hydrogen production components. As both scenarios had different SSR values of their respected energy demands, a conclusion of which scenario is more beneficial will be inadequate.

This project deals with the design of a weather station that can work completely offgrid. Its only source of power must be an embedded PV panel. The energy generated by the PV panel can be directly used by the station itself or stored in a battery. Energy can be drawn from the battery when the energy from the PV panel is not sufficient or totally absent (for instance during night). The design of this PV generator, tailored to the needs of the solar powered weather station, is vital to the effectiveness of the whole system. This thesis will discuss and cover, what measures should be taken to create a working prototype of a PV panel that can power the internal electronics of the weather station and what type of design is necessary to house the system as a whole. This design includes the housing of the electronics and the frame that is used to connect the panel with the housing. This frame could also be mounted to a pole. This also includes how many solar cells are necessary. Or the possible angles for the solar panel, and what influence they have on the lifetime and reliability of the system.

Drones are unmanned flying vehicles, which can be used for a broad spectrum of different applications. One of these applications is the generation of albedo maps. However, it could take some time to map an area. Therefore problems can occur the with respect to its flight range, which typically lies between 20 to 45 km for mini UAVs. The goal of this project is to design a PV powered drone that can create an albedo map of an area that is equal or bigger than the area of the Technical University of Delft. This is done by choosing and modelling an UAV system, where after choosing and modelling a PV generator system. Based on these models, power dynamics and flight ranges are calculated. The usability is tested for different weather conditions of Delft. The UAV system with PV generator without protection layers has a flying range between 129 and 250 km, depending in the irradiance. For the same system with protective layers, the flight range varies from 117 to 208 km. the total flight range that is needed to map the area of the TU Delft is 48.75 km. Therefore, there can be concluded that in both cases our goal has been achieved. When these results are compared to the weather conditions of the TU Delft, it can be concluded that on average a UAV system with PV generator will increase the flight range. However, when comparing this system to a system with additional batteries, the latter will achieve better results. In order to make sure that the PV generator system will guarantee a longer flight range, limitations regarding times, periods and places are made. Keep in mind that since these results are solely based on models of systems, it's best to create and test the physical system to validate the found results.

This thesis is written in context of the Bachelor Graduation Project. We would like to express our gratitude to our daily supervisor Patrizio Manganiello and our supervisors Andres Calcabrini and Mirco Muttillo for their guidance during the project.  Finally we would like to thank our colleagues: Laura Muntenaar and Sjoerd de Groot of the control algorithm project and Jetse Spijkstra and Martin Geertjes of the power electronics project for an enjoyable and productive collaboration.

J. Koning & R. van der Hoorn
Delft, June 2020

With the strict Paris climate goals, all eyes are set on the development of sustainable solutions that can replace or improve commercial solutions. This thesis revolves around the design and implementation of a subsystem for the creation of a solar powered drone. The goal of the solar powered drone is increasing the flight range of a commercial drone with the addition of photovoltaic (PV) panels. The subsystem designed and implemented in this thesis is split up into two separate systems namely, the control part and the image processing part. The control part revolves around the design, implementation and validation of Maximum Power Point Tracking (MPPT) for the PV panels. The image processing part revolves around the design, implementation and validation of an albedo processing pipeline.
For the MPPT, a variable step size perturb and observe algorithm has been implemented with a worse case tracking delay of 40 milliseconds during a change of irradiation from $900 W/m^2$ to $100 W/m^2$ and and more than 99\% power efficiency in steady state conditions. For the albedo pipeline, multiple RAW images are loaded one after another. Vignette correction is applied making the pixel values at the edges and the center of the image compatible with each other. The user can annotate a known reference target that is used to calibrate the albedo generation. Finally, the images are stitched together using Open Drone Map to create a complete albedo map. The results indicate accurate visible band albedo generation, however additional sensors would be needed to obtain wide band albedo generation.

The installation of photovoltaic systems in the urban environment is becoming increasingly common. These photovoltaic systems are affected by a large fraction of reflected irradiance as well as partial shading. In a similar way these issues also have an important effect on bifacial photovoltaic power plants. Irradiance models that are able to take these issues into account are therefore gaining interest. For an accurate economic assessment of a PV system and the calculation of delivered power it is becoming very important to be able to accurately determine the irradiance on a PV system. Therefore there is a rising demand for accurate irradiance models that are able to take into account the effects that arise in complex geometric scenarios. The research in this thesis report aims to develop such a model which is able calculate the irradiance incident on bifacial modules and PV arrays in complex landscapes by combining the concepts of ray tracing and 3D view factors. The implementation of the proposed model decouples the irradiance simulation into independent blocks that allow to efficiently calculate the spectrally-resolved irradiance incident on a PV module. This decoupling makes the proposed model suitable for simulation of tandem devices in the near future. The developed simulation has been experimentally validated using measurements from the PVMD monitoring station and also in comparison with other sophisticated irradiance simulation models. Experiments with a large fraction of specular reflected irradiance showed a good match between the measured and the simulated irradiance. Validation over a longer time period was also performed for 3 different sensors on the PVMD monitoring station roof. The results show an overall low mean bias error between the measured and simulated irradiance for the time period between mid-August 2020 to mid-October 2020. The proposed model is able to model the irradiance impinging on a PV system in a complex urban environment using a decoupled structure and its performance is comparable to sophisticated existing ray tracing models. The performed simulations show a good match with the measurements for different situations. Further improvements are the implementation of higher order reflections, computational optimization and more extensive validation.

Trolleybus systems may be a sustainable and cheap alternative to diesel and battery buses. However, to improve sustainablity, the trolleybus system must be powered by renewable energy sources. In this work, a case study on the Arnhem trolleybus grid is performed. First the bus power demands and bus traffic are constructed for the whole system, afterwards Photovoltaics and wind energy sources assited by ESS are sized to investigate the effects on renewable power utilization. It was found that for the Arnhem trolleybus system, a centralized approach with equal shares PV (51%, 4.3 MWp) and wind (49%, 1.75 MWp) and diurnal energy storage (5MWh - 10MWh) can provide a 72% to 78% of the total trolleybus load. This system will reduce the CO2 emissions by 80% over a 30-year lifespan.

Sustainable energy technologies are ever-increasing in popularity, not only among companies but also among consumers. Photovoltaic, or PV, cells are amongst the most well known in this field. This project was set up for designing a PV-powered UAV that is able to generate an albedo map of an area equal or bigger than the campus of the TU Delft in a single run. PV cells, however, are highly susceptible to changes in weather conditions and have a range of voltages at which these cells can supply power. Besides that, unnecessary losses occur if the so-called ’Maximum Power Point’ (MPP) is not tracked. In this thesis, a boost converter is proposed for the aforementioned system to implement the maximum power point tracking and supply the, by the PV system produced, power as efficiently as possible to the UAV power system.

In urban environments, more and more building added and building integrated photovoltaic (PV) systems are found. These systems use conventional solar modules which have a poor performance under non-uniform illumination conditions. When the module is partially shaded, either at least one
subgroup is bypassed or the module current is limited by the current of the worst performing cell. This leads to significant and disproportionate power losses. One way to address this issue is to implement a solar module made of low reverse breakdown voltage (BDV) solar cells.
A thermo-electric simulation framework was developed in MATLAB to replicate two types of commercially available low BDV solar cells: Sunpower Maxeon gen2 and gen 3 cells. Using the above model the potential and performance of solar modules in urban landscapes has been evaluated. A comparative study of solar module models built with these cells and placed on three different locations on a single rooftop having completely different irradiance profiles has been assessed. A solar module with 3 bypass diodes made of gen 3 solar cells has a better performance than module made of gen 2 cells. This accounts not only for better forward parameters of gen 3 cells but also its improved mismatch losses owing to lower reverse breakdown voltage and better temperature coefficients.
The usage of low reverse breakdown solar cells is beneficial in conditions where partial shading is predominant. Other advantages of using these solar module over other technologies is there is that there is no need of any additional electronic components.