A hydrophobic coating system for solar photovoltaics

Abstract

A hydrophobic coating system for solar photovoltaics, comprising: a nanostructured roughness layer comprising nanoparticles selected from silicon dioxide (SiO2), aluminum oxide (Al2O3), or titanium dioxide (TiO2), wherein the nanoparticles have an average particle size in the range of 20 nanometers to 150 nanometers and are configured to create a micro- and nano-scale surface structure on the disk substrate; a hydrophobic matrix layer applied over or mixed with the nanostructured roughness layer, the matrix layer comprising a polymer selected from polydimethylsiloxane (PDMS) or a fluorinated silane, the layer imparting low surface energy, smoothness, and water repellency to the coated surface; a UV-resistant protective layer formed by incorporating UV-stabilizing additives selected from titanium dioxide (TiO2), zinc oxide (ZnO), or hindered amine light stabilizers (HALS), the layer being configured to improve durability and resist photochemical degradation upon prolonged exposure to sunlight; wherein the coating system (100) has a water contact angle of at least 150° and an optical transparency of at least 90% in the visible spectrum and is applied to glass surfaces of mono- or polycrystalline solar PV modules; and wherein the coating is configured for application by one or more deposition processes selected from sol-gel, spray coating, dip coating, spin coating, or plasma-enhanced chemical vapor deposition.

Description

[0001] The present invention relates to the field of surface coatings for photovoltaic systems. In particular, it relates to a hydrophobic, self-cleaning, and UV-resistant coating system for photovoltaic (PV) modules inspired by biomimetic principles. It serves to increase energy efficiency, reduce maintenance requirements, and extend the service life of solar modules exposed to environmental dust, water, and pollutants.

[0002] Solar photovoltaic (PV) systems are increasingly being used to generate renewable energy across diverse geographic regions. However, one of the biggest challenges to their long-term performance and efficiency is the accumulation of dust, water stains, and environmental contaminants on the surface of PV modules. This leads to a significant reduction in light transmittance and energy yield, with power losses of up to 30% reported in dusty environments. Conventional methods to address this problem typically involve manual or semi-automatic cleaning systems, which often require significant water consumption, frequent maintenance, and increased operating costs.Some previous approaches include dust-repellent or water-repellent coatings; however, these often suffer from insufficient durability, degradation under UV exposure, poor transparency, or reliance on chemical cleaning agents that may not be environmentally friendly. Existing coating technologies are also limited in their functionality and often only solve one problem at a time—either dust repellency, UV protection, or water repellency—without providing a holistic and durable solution suitable for harsh outdoor conditions. Therefore, there is a need for a multifunctional, robust, and scalable coating system that not only provides superhydrophobic property to repel dust and water, but also exhibits high optical transparency, strong UV resistance, and mechanical durability.The present invention closes this gap by introducing a biomimetic hydrophobic coating system inspired by the lotus leaf effect, utilizing a combination of silica or alumina nanoparticles, UV-resistant additives, and a durable polymer matrix such as polydimethylsiloxane (PDMS) or fluorinated silanes. This innovation offers an effective, environmentally friendly, and industrially viable solution for improving the operational efficiency and sustainability of solar PV systems.

[0003] To solve the problem, the present invention provides a hydrophobic coating system for solar photovoltaics.

[0004] The system features a superhydrophobic surface treatment that enables self-cleaning capabilities, effectively reducing the need for manual or water-intensive cleaning processes.

[0005] The system protects the surfaces of the solar modules from UV-induced degradation while ensuring high optical clarity and energy conversion efficiency.

[0006] The system consists of nanoparticles such as silicon dioxide (SiO2) or aluminum oxide (Al2O3) embedded in a polymer matrix such as polydimethylsiloxane (PDMS) or fluorinated silane, making it suitable for industrial-scale production.

[0007] The system reduces maintenance costs and promotes sustainability in solar energy production, especially in dusty and UV-stressed environments, thereby extending the service life of PV modules.

[0008] In one embodiment, the present invention provides a hydrophobic coating system for photovoltaic (PV) modules that significantly improves energy efficiency, reduces maintenance frequency, and extends the lifetime of the modules. The invention incorporates a bio-inspired, self-cleaning surface treatment based on the lotus leaf effect, which imparts superhydrophobic properties to the surface of the solar module.The system comprises a multilayer coating comprising: (i) a nanostructured roughening layer of silicon dioxide (SiO2) or aluminum oxide (Al2O3) nanoparticles to create micro / nano surface structures; (ii) a hydrophobic layer of polydimethylsiloxane (PDMS) or fluorinated silanes to improve water repellency and surface smoothness; and (iii) a UV-resistant layer containing additives such as titanium dioxide (TiO2), zinc oxide (ZnO), or hindered amine light stabilizers (HALS) to protect the coating from environmental influences. The coating system maintains high optical transparency (≥90% in the visible spectrum) to ensure optimal absorption of sunlight. It achieves a water contact angle of >150°, enabling efficient self-cleaning by repelling water droplets and preventing the adhesion of dust and dirt.The coating can be applied to glass substrates of monocrystalline or polycrystalline PV modules using industry-standard techniques such as sol-gel coating, spray coating, dip coating, or plasma-enhanced chemical vapor deposition. This multifunctional coating improves module performance by reducing light-blocking contaminants, reducing water and labor requirements for cleaning, and providing long-term protection against UV radiation and surface wear. The invention is cost-effective, scalable, and suitable for widespread use in dusty, hot, or remote locations where regular manual maintenance is impractical.

[0009] The invention is explained again below.

[0010] The present invention relates to a hydrophobic coating system developed to improve the performance, durability, and self-cleaning properties of photovoltaic (PV) modules. The invention is inspired by the lotus leaf effect and mimics its micro- and nanostructured surface properties to create a superhydrophobic, water-repellent layer that minimizes energy losses due to dust and water accumulation while reducing maintenance requirements. The coating system comprises three key functional layers. The first is a nanostructured roughening layer formed using nanoparticles such as silicon dioxide (SiO2), aluminum oxide (Al2O3), or titanium dioxide (TiO2) with particle sizes between 20 nm and 150 nm. These nanoparticles are deposited to create a surface with hierarchical roughness at both the micro- and nanolevels.This surface structure reduces the contact area between contaminants and the panel surface and promotes self-cleaning through the beading of water droplets. The second layer is a hydrophobic matrix that provides water repellency and mechanical stability. This layer is made of a polymer material such as polydimethylsiloxane (PDMS) or a fluorinated silane. These materials improve surface smoothness and ensure low surface energy, which further supports water beading and dust removal. The polymer layer also improves the adhesion between the nanostructured surface and the solar module substrate. The third functional layer is a UV-resistant protective layer integrated into the matrix. This contains additives such as titanium dioxide (TiO2), zinc oxide (ZnO), or hindered amine light stabilizers (HALS), which prevent photochemical degradation and extend the lifetime of the coating.These components absorb or reflect ultraviolet radiation, ensuring that the coating remains stable even under prolonged exposure to sunlight. The coating can be applied to the surface of the solar module using scalable and cost-effective deposition techniques, including spray coating, dip coating, spin coating, sol-gel processes, or plasma-enhanced chemical vapor deposition (PECVD). After application, curing processes such as heat treatment can be performed to improve the stability, adhesion, and durability of the coating. Functionally, the coated surface achieves a water contact angle of at least 150°, which allows it to be classified as superhydrophobic. This allows water droplets to easily roll off the surface, carrying dust and other particles with them.The coating maintains an optical transparency of 90% or greater in the visible spectrum, ensuring minimal interference with solar energy conversion. Coating thickness is typically between 50 nm and 500 nm, and surface roughness (Ra) is maintained between 100 nm and 500 nm to optimize hydrophobic performance without compromising light transmission. The invention is compatible with both monocrystalline and polycrystalline PV glass substrates. Surface treatment techniques such as plasma activation or the use of silane coupling agents can be employed to improve adhesion between the coating and the glass. The coating offers significant environmental and operational benefits. It reduces water consumption for cleaning, minimizes the need for manual labor, and supports sustainable energy practices.This is particularly useful in arid and semi-arid environments with high dust levels and limited water availability. In a representative working example, a dispersion of 80 nm silicon dioxide nanoparticles in a PDMS-toluene mixture was spray-coated onto the surface of a monocrystalline PV panel. After thermal curing at 100°C for one hour, the coated module achieved a contact angle of 153°, a transparency of 91%, and retained more than 95% of its performance over a period of 60 days outdoors. Dust and water stains were effectively repelled, confirming the self-cleaning and durability claims of the coating.

Claims

[1] A hydrophobic coating system for solar photovoltaics, comprising: a nanostructured roughness layer comprising nanoparticles selected from silicon dioxide (SiO2), aluminum oxide (Al2O3), or titanium dioxide (TiO2), wherein the nanoparticles have an average particle size in the range of 20 nanometers to 150 nanometers and are configured to create a micro- and nano-scale surface structure on the disk substrate; a hydrophobic matrix layer applied over or mixed with the nanostructured roughness layer, the matrix layer comprising a polymer selected from polydimethylsiloxane (PDMS) or a fluorinated silane, the layer imparting low surface energy, smoothness, and water repellency to the coated surface; a UV-resistant protective layer formed by incorporating UV-stabilizing additives selected from titanium dioxide (TiO2), zinc oxide (ZnO), or hindered amine light stabilizers (HALS), the layer being configured to improve durability and resist photochemical degradation upon prolonged exposure to sunlight; wherein the coating system (100) has a water contact angle of at least 150° and an optical transparency of at least 90% in the visible spectrum and is applied to glass surfaces of mono- or polycrystalline solar PV modules; and wherein the coating is configured for application by one or more deposition processes selected from sol-gel, spray coating, dip coating, spin coating, or plasma-enhanced chemical vapor deposition. [2] The system of claim 1, wherein the nanoparticles are present in a concentration range of 0.5 to 5 wt% in the polymer matrix. [3] The system of claim 1, wherein the polymer matrix comprises polydimethylsiloxane (PDMS) having a viscosity in the range of 50 cSt to 1,000 cSt. [4] The system of claim 1, wherein the surface roughness (Ra) of the coated layer is in the range of 100 nanometers to 500 nanometers. [5] The system of claim 1, wherein the water contact angle of the coated surface is between 150° and 170°. [6] The system of claim 1, wherein the UV-resistant additives are present in an amount of 0.1 to 2 wt.% of the total coating formulation. [7] The system of claim 1, wherein the coating thickness is in the range of 50 nanometers to 500 nanometers. [8] The system of claim 1, wherein the coating retains at least 90% of its hydrophobicity and optical transparency after exposure to ultraviolet light for a period of 1,000 hours. [9] The system of claim 1, wherein the coated solar PV panel exhibits self-cleaning behavior under natural rainfall conditions without the need for additional manual or mechanical cleaning.