Nanocoatings for Energy Generation and Conservation of Solar Cells

Introduction

Solar energy, being the most abundant and clean renewable green energy, has the fastest-growing use at the industrial, agricultural, commercial, and residential levels (Shaju, 2018; Hasan, 2022). The sun delivers 1367 W/m² to the atmosphere and the global absorption is in the order of 1.8×10¹¹ MW worldwide. The interest in studying, designing, and improving global power sources lies in the fact that their production in 2017 was 368 GW while it is projected that in 2030 production will be in the range of 3000 to 10,000 GW (Kumar, 2018). The emerging need for electrical energy generation around the world has allowed researchers to achieve, with their advances in research and installed capacity, that solar panels are the second fastest-growing technology and the third largest as a renewable technology (Ehsan, 2022). Solar cells convert light energy from the sun into electrical power using semiconductor materials. The main disadvantage of the energy that solar cells produce is that it is intermittent as it varies depending on climatic and environmental conditions. Furthermore, at the level of the photovoltaic panel, its performance in power delivery is diminished by other factors, among which are the technology and materials used in its manufacture, the mismatch of the components that make up the solar cell array, surface shape, orientation, angle of inclination, temperature, inverter efficiency, panel fouling, encapsulation materials, electrical charges, etc. as illustrated in Figure 1. Photovoltaic modules based on solar cells may be subjected to hazardous environmental conditions such as soiling during outdoor operation (Sun, 2018; Ehsan, 2021; Cherupurakal, 2021; Hasan, 2022). The particles may be wet or dry, may contain low or high organic content, etc. so the adhesion of them to the solar panel cover is completely different depending on the environment found in the place where the panel is installed. In the desert, the wind carries both sand and dust particles towards the solar panel, which reduces energy conversion efficiency. For example, environmental dust that accumulates on the surface of the module prevents sunlight from penetrating the solar cells, which reduces the electrical power produced by the panel. To increase the power conversion efficiency (PCE) of a solar cell, it is required that its Shockley-Queisser limit be optimized to reduce reflection losses at the transparent glass-air interface (Cherupurakal, 2021; Vasilopoulou, 2022). Approximately one-third of the incident light received by a solar cell is reflected, so its efficiency needs to be increased for solar cells to be attractive as renewable energy sources. Within the technological possibilities that have been proposed to solve this technical problem, it has been proposed to place coatings on the transparent side of the solar cell (Ehsan, 2021). Among the functions that nanocoatings must improve the performance of solar cells are redirecting incident light to trap it, improving light absorption in a wide range of wavelengths, and optimizing light handling. Among the proposals that have been used to improve the efficiency of solar cells are photonic crystals, diffraction gratings, surface textures based on honeycomb structures or inverted pyramids, and metamaterials. Among the changes being introduced are a reduction in the thickness of the solar cell from 400 to 200 microns and an expansion of the solar cell area from 100 to 240 cm² (Kumar, 2018; Cherupurakal, 2021). Advances in solar cell technology have allowed the Shockley-Queisser limit to be overcome, making it possible to achieve a power conversion efficiency of 41% for third-generation solar cells and even a reported 65% efficiency for solar cells based on silicon nanocrystals, cadmium telluride (CdTe) or copper indium gallium selenide (CIGS). Despite the advances achieved so far, solutions based on nanomaterials are being researched to offer simpler, lighter, and more cost-effective nanocoatings. The purpose of this chapter is to review the state of the art of the main contributions based on nanomaterials to implement nanocoatings to optimize the performance of solar cells.