Enhancing the Performance of Photovoltaic (PV) Panels Using Anti-Soiling Coatings Techniques

Global energy needs have gradually shifted from being primarily dependent on conventional energy resources towards renewable ones. Extensive research has been reported recently on Photovoltaic (PV) solar energy utilization, especially in the Gulf region due to the high solar irradiance potential. However, one of the main challenges for the efficient utilization of this technology in the region is the accumulation of dust on the PV panels in a phenomenon referred to as “soiling”. Soiling has been reported to significantly degrade the power output of the PV modules over time. Although several cleaning techniques have been proposed, anti-soiling coatings are among the promising technologies to minimize the adverse impact on PV solar panels. This research aims to understand the soiling mechanisms and develop anti-soiling coatings that are effective against dust accumulation and can maintain the PV module's efficiency.In the first part of this work, soiling characteristics and the impact of particle size, shape, and main adhesion forces on soiling severity are summarized. Moreover, several mitigation and mechanical cleaning methods were compared with passive mitigation techniques. In the second part of this work, inkjet printing was utilized to deposit metal oxide inks to form textured anti-soiling thin films over the glass substrates. Four metal oxides were used and compared: ZnO, TiO₂, Al₂O₃, and SnO₂. The reason for selecting metal oxide materials is due to their proven physio-chemical properties such as wide bandgap, self-cleaning ability, mechanical stability, and anti-reflectivity, which are all critical for anti-soiling applications. Moreover, inkjet printing for thin film coatings is a stateof-the-art technique that is easy to scale up and provides a high control on the formed pattern, which allows for the development of different textures of the deposited films to investigate their impact on enhancing the anti-soiling properties. The experimental part of this thesis has utilized two types of inks: (1) the mixed metal salts with metal oxide nanoparticles (NP), and (2) the pure metal oxide nanoparticles. Hence, a combination of micro and nanostructured films was developed and characterized. Furthermore, the novelty of this work is not only related to using inkjet printing for anti-soiling application, but also in the combination of micro and nanotextured films of different metal oxides for this purpose. This work also reports on the optical and morphological properties of the fabricated films which are critical for PV power output. Moreover, UV-VIS spectroscopy, total transmittance (TT), total reflectance (TR), field emission scanning electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy were systematically used to investigate the characteristics of the anti-soiling films. The contact angle measurements were also obtained to assess the hydrophobicity of the coatings.Our results showed that the substrate's transmittance using nanoparticle (NP)-inks revealed better optical properties than the mixed-based-inks. This optical enhancement might be due to the presence of NP voids, which reduce the spectra scattering and deterioration and, thus, have better optical properties. A homogeneous layer is also observed in all samples with dense NP in ZnO, TiO₂, and SnO₂ mixed inks compared with NP samples. The contact angles were found to be ranging between 8.5o to 47.8o , thus indicating that the synthesized films are hydrophilic/super-hydrophilic coatings. In this research, thermodynamic modeling and analysis of the PV cells with different semiconductors and anti-soiling coatings (ASC) were comparatively conducted. Thermodynamic analysis revealed that coated cells have better efficiencies in terms of energy and exergy over the uncoated ones after dust exposure for about two weeks. The exergy efficiencies of GaAs type PV cells were found to be 14.6% and 15.21% for the uncoated and coated cases; respectively. The exergy efficiency for the uncoated Si PV type cell was found to be 15.13%, whereas it was about 15.74% for the anti-soiling coated Si PV cell. At 298K of ambient temperature, the energy and exergy efficiencies for the coated cells of the GaAs PV were calculated and found to be 14.66% and 15.33%; respectively. Our developed thin films were tested outdoor to assess their anti-soiling properties. Based on the outdoor testing, a reduction of 0.67% to 53% in the dust deposition rate was observed on all coated samples compared to the bare glass substrate except for SnO₂ NP-based thin film. It was found that mixed-based ink thin films, especially Al₂O₃, ZnO, and TiO₂, were better in terms of having the minimum dust deposition rate compared to the NP-based ink thin films and bare glass.