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.

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

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.

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 today’s society, the need for alternate high-speed data transmission solutions has increased due to the radio frequency (RF) spectrum’s growing congestion. Visible Light Communication (VLC)-based LiFi has emerged as a possible alternative to current wireless technologies like WiFi. The difficulty, though, is that the photodiode performance as a receiver for VLC under outdoor conditions rapidly degrades. To solve this problem, the photodiode receiver was replaced by a PV cell receiver with the primary advantage of being optimized for outdoor conditions. While earlier research has concentrated on light and modulation optimization to improve the performance of VLC systems, our research adopts a novel strategy by analyzing the effect of different light wavelengths on seven different PV cell technologies in hopes to design an optical filter and realize noise-free VLC for PV cells. We specifically are interested in identifying the LED wavelength that has the greatest bandwidth in order to increase the possible data transmission speeds in PV-VLC systems. In order to do this, a thorough characterization of several colored LEDs with different wavelengths was carried out across seven PV technologies, including PERC, AL-BSF (5INCH), AL-BSF (6INCH), SHJ, IBC, Busbar-free Al BSF, and TOPCon. Each LED wavelength was tested under three different intensities of light (100, 300, and 500 W/m2). In terms of PV technology, TOPCon demonstrated superior performance at low bias voltages, while Busbar-Free Al BSF(EEPV) outperformed the other PV technologies at higher bias voltages, especially at the maximum power point. Furthermore, the analysis of light intensity revealed that the bandwidth does not only depend on capacitance but also on the internal resistance of the PV laminate. For the c-Si solar laminates tested the considerably larger resistance at lower light intensities in the bias voltage interval from 150mV to 450mV resulted in lower bandwidths at lower light intensities. The measurement results under different LED colors, concluded that when operating near maximum power point, the variation in bandwidth between different colored LEDs could significantly affect data rates, particularly when considering the higher SNR results at lower bias voltages that contribute to achieving faster data rates in the PV-VLC system.

The considerable increase in the number of devices needing connectivity, such as mobile phones and Internet of Things (IoT) devices, has led to an exponential rise in data volumes during the last years, that will surely continue over the next decade. Therefore, it will be increasingly challenging to provide sufficient RF resources. A novel alternative to RF communications is Visible Light Communication (VLC). VLC is a communication technology that uses visible light as an information carrier. The use of VLC for indoor applications has been rapidly growing during the last years – Light Fidelity (LiFi) technology is an example of VLC application – with photodiodes being the most widely used receiving devices. However, looking at both indoor and outdoor communication, photovoltaic (PV) cells represent a relevant alternative for detecting the information. One of the advantages of using a PV cell as receiver is the huge sensitive area for detection of the information that simplifies alignment between transmitter and receiver. Different light sources can be used in VLC. Typically, either LEDs or LASERs are considered, depending on the characteristics of the link (such as distance, type of receiver, indoor/outdoor application). These light sources differ in terms of spectrum, directionality, optical power density and bandwidth. The performance of the whole VLC link strongly depends on the characteristics of the light source, since it affects the ability of the receiver, such as a PV-device, to detect the information when it overlaps with the ambient light, that can reach very high values, especially in outdoor applications where the ambient light is the sunlight. Therefore, the modelling and analysis of the performance of different light sources in a PV-based VLC link will pave the way towards the realisation of a PV-based communication system of the future; and it is the focus of this thesis project. The project goals were achieved by first reviewing the characteristics of light sources, to understand their advantages and drawbacks in (PV-based) VLC. This was followed by the development of models of the VLC data-link, with a focus on the light source, which took into account various factors such as the type of light source, its location relative to the receiver, and its dynamic behaviour. This was followed by the realisation of a test setup, to characterise different light sources, and the models were then used to simulate the light distribution from the actual light sources. Finally, the framework was used to simulate a LED-based solar simulator and an outdoor VLC data-link.

This thesis project explores the role of photovoltaics in visible light communication (VLC). It focuses on the development of a theoretical model suitable for the study of various photovoltaic (PV) technologies in their role as a receiver in light communication systems. These photovoltaic technologies are characterized based on the energy which they are able to harvest as well as their bandwidth, to quantify the achievable transfer rate for the different photovoltaic technologies. The AC equivalent circuit is considered, where the solar cell capacitance depends on its operating point. A fitting is made of the model with the experimental results in order to estimate the dynamic parameters of different solar cells that were already available in the laboratory of the Photovoltaic Materials and Devices (PVMD) group. To characterize the dynamic behavior of solar cells, an ad-hoc test bench will be realized.