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.

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.

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.

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.

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