Technological advancements often make us think of the components inside a device, but sometimes a component on the outside is a big deal. That’s the case with a new coating that improves solar energy technology performance. 

Researchers at Case Western Reserve University in Ohio partnered with the University of Rochester in New York to create a new class of optical coatings that could make photovoltaic cells used for solar energy last six times longer while cutting energy system costs.

What they are

Optical coatings are layers of material installed on a surface to identify different light wavelengths and either reflect or filter each wavelength. Optical coatings are put on many lenses, from eyeglasses to telescopes, to filter out harmful or unnecessary light wavelengths. They can allow specific beneficial light wavelengths to pass through the lens, such as for harnessing solar energy.

PV problems

Because of the simple fact that they harness sunlight, photovoltaic panels efficiently generate energy during the day but not at night. However, energy demand is lower during daylight hours and higher at night — exactly the opposite of when it can be efficiently produced. Energy storage technologies alleviate that problem but currently are expensive. In addition, standard operations can cause solar panels to overheat, which shortens their life.

The innovation

The research team created a very thin film to be used as an optical coating. It can simultaneously reflect and convert the same wavelength of light. Up until now, no optical coating could perform both functions with the same wavelength; they could only reflect some wavelengths while converting others.

The new coatings could be fine-tuned to reflect only a small light wavelength range that is known to efficiently produce electricity in a PV cell. The coatings could also be made to absorb the rest of the light spectrum and convert that energy into heat. Thermal energy is inexpensive to store compared with electricity, thus easing the energy storage cost problem.

In addition, the heat capture process would prevent the PV cell from overheating. Solar cells equipped with the new optical coatings potentially could last six times longer than existing models.

What’s next 

The researchers developed the coating, but scaling it and integrating it into a full solar energy system will take some time. The scientists say the optical coating discovery is an important first step. It holds promise for a variety of other applications as well, including sensors and imaging.

“We’ve done something that hasn’t been done in a century of development of optical coatings — and even we don’t know all of the applications that could come from this,” Giuseppe Strangi, a physics professor at Case Western Reserve University, said in a news release.