Titanium oxide hydrophobic coating to clean solar panels


Germany's Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology (FEP) claims to have applied crystalline titanium oxide to ultra-thin glass for the first time in a roll-to-roll process.

“The ultra-thin and lightweight glass can be applied subsequently to facades or directly incorporated into solar modules as a composite material – and even onto curved surfaces,” said Fraunhofer FEP researcher Valentin Heise. “Dirt-repellent, easy to clean surfaces ensure transparency and cleanliness for facades and more efficient and consistent energy production for solar, with less maintenance costs.”

The researchers explained that titanium dioxide is a material that is hydrophobic when is not exposed to ultraviolet (UV) radiation and superhydrophilic when radiated.

“In the case of photoinduced hydrophilicity, the surface changes from hydrophobic to superhydrophilic after approximately 30 minutes of irradiation with sun-like UV light,” they stated.

They said that the dirt on the solar panels can be removed by the coating at night, when the hydrophobicity of the surface washes it away through the beading raindrops. The cyclical alternation of hydrophobic and superhydrophilic effects prevents the dirt to adhere to the panel surface during the day.

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The scientists fabricated the first coating prototype with long roll of thin glass with a thickness of 100 micrometers. They used a titanium oxide film with a thickness of 30 nanometers to 150 nanometers and a pilot plant for roll-to-roll coating provided by German equipment supplier Von Ardenne.

The research team said it is currently working on improving by adjusting the properties of titanium dioxide and thin glass in a cost-efficient way.

“In the future, work will also be done by Fraunhofer FEP on layer systems that can be activated not only with UV light but also with visible light,” they said. “The production and embedding of nanoparticles or doping with nitrogen, for example, are also being considered.”

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