The use of clean energy sources for meeting the world’s energy requirements is increasing at an exponential rate, thus opening up new areas for research and development. The second generation of photovoltaics, especially flexible thin-film solar cells, are increasingly being used over the first generation crystalline silicon technologies due to their lightweight, flexibility, low cost, and decent efficiency. The low cost is possible mainly as a result of using a thinner absorber layer compared to crystalline silicon technologies. However, the thin absorber layer mandates the use of efficient light management techniques in order to increase the solar cell performance, as otherwise, the thin absorber layer will lead to very low photon absorption. Modulated surface texturing is one such light management technique where different textures are introduced at different interfaces and finally stacked together in order to superimpose various scattering mechanisms, thus increasing the optical path length of light. The modulated surface texturing principle has two goals: first, to provide efficient light trapping, and second, to promote the growth of smooth & dense high-quality nc-Si layers. 
HyET Solar B.V. is a company located in the Netherlands that uses state of the art roll-to-roll technology to manufacture flexible thin-film silicon solar cells. This thesis is a part of the ongoing FLAMINGO PV project in collaboration with TU Delft and HyET Solar B.V, to develop tandem & triple-junction solar cells with high efficiency & lifetime. HyET Solar B.V. uses an aluminum foil as a temporary substrate on which the TCO and subsequent solar cell layers are deposited. The goal of this thesis is to implement optimized modulated surface texturing for the solar cells developed at HyET Solar B.V, by creating ’U’ shaped micro-sized craters on the aluminum foil and subsequently depositing ’V’ shaped, naturally nanotextured FTO on it. The microtextures are created on the aluminum foil by the process of wet chemical etching, where the three main etching parameters- temperature, concentration, and time are varied in order to obtain the most suited recipe. An alkaline-based etchant (NaOH) is used for the wet chemical etching process. The textured features on the aluminum foil are analyzed for its morphological and optical properties. The morphological analysis using a 3D laser scanning microscope & SEM helps in obtaining the surface roughness properties while the optical analysis using Integrating sphere and ARTA helps in measuring the light scattering effectiveness. To ensure the mechanical stability of the roll-to-roll machine, a minimum foil thickness of 95μm is required after etching. Taking this as the first requirement, the etching recipes were varied and optimal results were obtained when the aluminum foil was textured with 60g/L NaOH at 60°C for 2.5 mins (NaOH60) and 60g/L NaOH at 70°C for 1.5 mins (NaOH70). Further analysis showed that texturing using NaOH60 resulted in better surface roughness and scattering properties compared to the aluminum foil textured with NaOH70, and it was thus chosen as the optimal recipe. This optimized recipe is known as FLAM02. 
 The TCO leak tests at HyET Solar B.V. showed that the aluminum foil contains pinholes & milling tracks, which are further enhanced after texturing using the factory baseline and FLAM01 process. Initial results showed that annealing the foil before texturing leads to a reduction in pinhole density & surface roughness caused due to milling tracks. Experiments were designed to validate this where the two annealing parameters - temperature and time were varied. The aluminum foils were textured after annealing using the factory baseline, FLAM01, and FLAM02 processes. Morphological analysis, which was conducted before and after texturing, showed that annealing the foil before texturing does not lead to a decrease in pinhole density and surface roughness due to the milling tracks. The optical analysis using laser scattering validated this. One observation was that texturing using the FLAM02 process led to the significant amount of aluminum foil being etched away, thus resulting in the reduction of milling track roughness and pinhole density.