Solar energy is predominantly harvested under the AM 1.5G spectrum. However, with the expanding integration of PV into Internet of Things (IoT) devices, such as sensors, actuators, Radio Frequency identification (RFID) tags and Bluetooth beacons, has sparked a growing research interest in indoor photovoltaic (IPV) technologies. As the IPV market expands and IoT devices become more affordable, there is significant potential for energy harvesting from indoor environments. Among the IPV technologies, Perovskite solar cells are leading due to their tunable bandgap, high absorption coefficients, defect tolerance and low fabrication costs. This thesis investigates the performance of Perovskite solar cells under indoor lighting conditions, characterized by low-intensity, narrow-spectrum light sources such as LEDs, compact fluorescent lamps (CFLs), and incandescent lamps. The primary objective of this research is to compare the indoor performance of Perovskite technology with other photovoltaic technologies, namely Silicon, Organic photovoltaic (OPV), and CIGS, available in the EnergyVille2 lab at imec, Belgium. The study was conducted using an experimental setup
designed to replicate controlled indoor lighting conditions, with adjustable illumination levels and controlled distances between the PV devices and light sources.
The study also involved analyzing the spectral profiles of typical artificial light sources, including LEDs, CFLs, and incandescent lamps, and determining the correlation between spectral irradiance and illuminance at varying intensities and distances resulting in finding out a linear relation between the spectral irradiance and illuminance of the light source. Subsequently, the performance of Perovskite and other PV technologies was evaluated under different light sources, including warm CFL (2700K), cold LED (4000K), warm LED (3000K), and cold LED (6500K), across illumination ranges from 100 lx to 1000 lx, using experimental setups at imec and CHOSE (Center for Hybrid Organic Solar Energy), Italy.
Results showed that Perovskite technology demonstrated the highest efficiency of 17.52% under warm LED (3000K) at 1000lx illumination, followed closely by OPV (10.9%), which exhibited strong stability. Consequently, Silicon and CIGS showed an indoor performance of 7.05% and 5.97%, respectively at 1000lx under warm LED(3000K). Overall, the findings indicate that perovskite technology demonstrates the highest performance among the tested PV technologies and provide valuable insights into the working of different PV technologies in indoor environments.

This thesis aims to enhance the performance of solar cells, specifically those used by Solarge, through comprehensive research on optical characterization and texture fabrication.
In the first part, the focus is on understanding and optimizing the optical properties of Solarge's polymer front sheet and encapsulant. Through meticulous measurements, both computationally and experimentally, the thickness and optical constants of each layer are determined. This information is used to develop an accurate optical model, validated against real-world measurements, to simulate the performance of Solarge's solar cell stack. Additionally, electrical performance is thoroughly evaluated using a combination of computational and experimental techniques.
The second part of the research delves into the fabrication of textures on Solarge's front sheet to minimize optical losses. Two fabrication methods, release papers and Teflon sheets, are examined, and a diverse range of texture morphologies undergo rigorous experimental testing. These textures are carefully evaluated based on their optical and electrical characteristics. By analyzing the findings from the initial texture analysis, a set of requirements is established to guide further investigations and determine the most effective texture for Solarge's solar cell stack. A computational study is conducted to accurately simulate and analyze different texture geometries, including scaled-up bio-inspired textures, random pyramids, and corner cubes, using the advanced capabilities of GenPro4 software. Based on the results obtained, two texture geometries are recommended to Solarge for further optimization. The implementation of the first recommended texture demonstrates a significant increase of 2.65% in power output compared to the current Solarge cell stack.
A holistic perspective is provided through a simple financial analysis, evaluating the potential profitability and economic feasibility of implementing the recommended improvements outlined in this thesis. The research findings offer practical insights for Solarge, enabling them to enhance module performance, reduce optical losses, and potentially generate substantial revenue.
In conclusion, this thesis presents a comprehensive investigation into the optical characterization and texture fabrication for Solarge's solar modules. The research outcomes contribute to an improved understanding of the optical properties of the cell stack components and the impact of surface texturing on performance. By combining scientific analysis, experimental testing, and computational simulations, this research offers valuable recommendations to enhance the overall efficiency and profitability of Solarge's solar cell stack.

People worldwide have begun to feel the effects of climate change in recent years with unpredictable weather patterns, heatwaves, changes in precipitation, and sea level rise. To help mitigate climate change, photovoltaics (PV) is seen as a technology with the tremendous capability to satisfy the world’s electricity demands by tapping into renewable energy from the sun. There are various PV technologies available, each with its challenges; the newest upcoming material is perovskites. They have showcased an immense potential of further lowering the production costs of solar modules, lower material consumption, and promising high conversion efficiencies. The single cell efficiency has seen incredible improvement in the last decade to 25.7%. The next stage is the scaling up to module level and outdoor deployment. However, some significant challenges remain towards achieving this; one is its response to shading, which has been studied little thus far and will be investigated in this study. The increasing integration of PV into the close surroundings also means that integrated PV will be exposed to much more shading than a typical panel in a solar farm. It is imperative to understand the behavior of perovskite solar cells (PSCs) to shade, primarily due to the poor reverse bias behavior reported in recent years. Since the cells are typically connected in series, shaded cells dissipate energy by going into negative voltages. The response to shading of any material also depends on the interconnection method adopted for the solar cells. So, several interconnections were identified in the project, a few including bypass diodes to improve shade tolerance. Due to the poor reverse bias characteristics of the PSCs, the interconnections and shading were modeled using Matlab and Simulink to better understand the interconnection configuration with the least power mismatch losses. Total Cross Tied (TCT) with bypass diodes was identified as the optimal configuration. Furthermore, the TCT interconnection with bypass diodes was tested experimentally on a shading setup to validate the model. The experiments confirmed the modeled results. None of the modules degraded under shading for the interconnection as the cells did not experience large enough reverse bias voltages. Additionally, tests were conducted to gain deeper insights into the degradation mechanism of perovskites. Shading was tested on a single module, parallel and perpendicular to laser scribes, to confirm that the degradation was due to reverse bias voltage. When the module was exposed to an Electroluminescence (EL) test after shading, it revealed the degradation through the formation of dark spots. The degradation is speculated to form due to the formation of shunt paths caused by the migration of copper into the absorber layer. A similar test was conducted on semi-transparent modules that did not lead to degradation. Also, the modules were tested to find their reverse breakdown voltage. It was observed to breakdown at -6.5V, translating to a cell breakdown at -1.6V. Interestingly, the module’s performance was slightly regained under light soaking for one hour in forward bias due to the reversal of the ion movement, which occurred in the reverse bias condition. The research into the shading of PSCs is still in the early days; many further topics for the future are proposed that could be interesting for later research.

In 2022, the Power conversion efficiency of perovskite solar cells has achieved an efficiency of >25\%. The cost-effective and flexible perovskite-based photovoltaic has been identified as an ideal solution to increase the integration of photovoltaics in buildings. However, for a large scale implementation, the perovskite photovoltaic must perform at its best and be highly stable. The upscaling of perovskite-based solar cells to the module must be done at minimal losses.

The following research is performed on an opaque double cation p-i-n perovskite module of aperture area 4 $cm^2$. The focus is on the laser scribing patterning technique to develop a quality interconnection in a module. The various laser parameters to be optimized and the approach to achieve a quality P1-P2-P3 scribe for the module are reported. With an ultrashort pulsed laser, the ablation of photoactive perovskite material varies remarkably. There are many possible scenarios regarding the level of ablation of $NiO_{x}$ and ITO using a picosecond pulsed laser with a wavelength of 355nm. In this study, the characterization concerning the emergence of contact resistance at ohmic contact is essential to identify the optimal ablation for interconnection in the module. The optimization is performed using a Scanning electron microscope in EDS mode, optical microscope, and Transmission line measurement. It helps to study the impact of different parameters on interconnection in a device.

This research shows that it is optimal to ablate beyond the HTL to completely remove the $NiO_{x}$ and minimize the contact resistance. The optimized laser parameters for each scribe helped achieve an optical gain, by reducing the dead area in a module. It helped in improving the geometrical fill factor by 3\%. Furthermore, the set of laser parameters also helped improve the electrical performance of a module by minimizing the drop in FF\% when up-scaled from cell to module. The obtained results show an encouraging outlook for further optimization of the module by studying other laser parameters and could fast-track the up-scaling of the perovskite module with negligible interconnection and inactive area losses.

Bifacial modules are expected to have a 60% share in the PV market, which require spectral irradiance data incident on both sides to optimize the design. Sensors that provide spectrally resolved data are expensive and thus a cost-effective spectrally resolved albedometer was designed in two previous PVMD Master Theses. This albedometer measures irradiance in three wavelength bands. The focus of this research is on developing a model that reconstructs the spectral irradiance incident on the top part of the albedometer.

The spectral simulation program SMARTS was converted to MATLAB, after which a Particle Swarm Opimization Algorithm was added to determine values for unknown parameters. The model was first tested against spectra generated by SMARTS. After which both the original model and an model with additional modification coefficients was tested with clear-sky measurements from the albedometer and validated against an EKO spectroradiometer.

The original model proved to fail in the first wavelength band, which caused the other wavelength bands to be reconstructed poorly as well. The adjusted model performed close to the performance of the EKO for clear-sky irradiances above 400 J/Z2 in the total albedometer region, 320-1100 nm.