Scientists Pursue Colorful Solar Dream

FRIDAY, JULY 5, 2013

Step into the light, colorful solar panels.

Traditional black and blue panels generate electricity but lack the aesthetic flexibility that designers and architects crave, say German researchers who are hatching alternatives.

The team, from Fraunhofer Institute for Applied Optics and Precision Engineering IOF in Jena, is investigating cost-effective techniques and manufacturing processes to increase both the efficiency and design flexibility of solar panels.

“Not enough work has been done so far on combining photovoltaics and design elements to really do the term ‘customized photovoltaics’ justice,” said Kevin Füchsel, project manager at the Fraunhofer Institute.

The physicist has spent the past four years studying nanostructured solar cells suitable for mass production as part of a research group funded by Germany’s Federal Ministry for Education and Research.

Decorative Designs

Currently, Füchsel's team is working on the fundamentals of making colored solar cells from paper-thin silicon wafers, borrowing processes from thin-film photovoltaics.

The colored cells “will be particularly suited to designs for decorative façades and domestic roofs,” the team reported in a news release.

The scientists developed a semiconductor-insulator-semiconductor (SIS) solar cell, with a transparent conductive oxide (TCO) outer layer to capture more light.


Presently, only dark solar panels are widely available on the market, the researchers said.

“TCO has a lower refractive index than silicon, so it works as an anti-reflective coating,” Füchsel said.

The solar cell could be made in different colors and shapes, the team said.

“The color comes from changing the physical thickness of the transparent conductive oxide layer, or modifying its refractive index,” Füchsel said.

Color and Efficiency

Füchsel dismissed the idea that color affects the efficiency performance of the new SIS modules.

“Giving solar cells color doesn’t really affect their efficiency. The additional transparent TCO layer has barely any impact on the current yield,” he said.

Simulations showed that the SIS cells could be up to 20 percent efficient. In practice, the efficiency depends on the design of the solar panels and the direction the building faces.

However, Füchsel did note that not every color would generate the same amount of electricity.

“There are restrictions, for example, with certain blends of red, blue and green,” he said.

In addition to SIS solar cells, dye solar modules and flexible organic solar cells have also been used to provide new opportunities in façade design, the researchers said.

Buildings as Billboards?

The researchers also reported that laser-based optical welding processes will be used to connect several solar cells to create a single module.

Research at Fraunhofer
© Fraunhofer FIT

Fraunhofer scientists research many aspects of solar energy. Recently, a team announced a new software technology that can calculate where and when planned photovoltaic installations can cause glare—a development especially important for airplane pilots.

Further, an inkjet printing process in development could also be used to contact the conductive TCO layer on the silicon wafer, enabling faster manufacturing and additional degrees of design flexibility.

SIS solar cells could even be used to make large billboards that produce their own electricity.

“This opens up numerous possibilities to use a building to communicate information, displaying the name of a company or even artistic pictures,” Füchsel noted.

Patents already cover the production of colored cells, as well as the ability to integrate design elements into solar panels and whole modules, the researchers said.


Tagged categories: Aesthetics; Architecture; Building design; Color; Color + Design; Design; Energy efficiency; Nanotechnology; Research; Solar energy

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