The German research institute proposed a technology based on the surface structure of deformed butterfly wings to produce colorful BIPV panels for exterior walls and roofs. It is said that this process can color the module with optical effects instead of color pigments, because the latter will reduce its efficiency.

In addition to power generation, aesthetic issues are often related to the installation of BIPV systems. This is especially true when solar power generation is on the outer walls of buildings.

With this in mind, a team of scientists at the Fraunhofer Institute for Solar Energy Systems ISE has developed a process that enables it to produce solar modules with uniform surfaces and different colors, and then be "almost invisible" integrated on the external wall or roof.

The researchers' technique is based on the surface structure of deformed butterfly wings-this is a tropical American butterfly species with dazzling iridescent wings, usually with distinct blue areas. These wings have a fine surface structure on the micron level and can specifically reflect a narrow range of wavelengths. Fraunhofer ISE scientists successfully applied a similar surface structure to the back of the cover glass of their solar modules using a vacuum process.

Fraunhofer ISE’s Coating Technology and System Leader Thomas Kroyer said: “The flash idea developed is not to color the cover glass of the module with colored pigments, but to imitate the physical effect of butterfly wings. If you coat the glass on the glass Pigments, the efficiency of solar modules will drop a lot, because light can no longer penetrate the modules unimpeded."

The modular technology proposed by the scientists is labeled MorphoColor and relies on an optical effect. Depending on the structure, the cover glass can produce bright blue, green or red. Kroyer said: "About 93% of the light can penetrate this layer of glass - only about 7% of the light is reflected and cause color effects. The cover glass vapor deposited in the vacuum process can be laminated to form a photovoltaic module, or integrated into Solar heating is performed in the collector."

Both of these technologies can be applied to manufacturing with only one production line. In the future, photovoltaic modules and solar thermal modules can be given the same color and installed almost invisible on the roof or external wall. It can also realize a completely homogenous house wall and provide electricity and heat at the same time. A specially developed assembly method can also prevent the tile-sized photovoltaic cells that are welded together from flashing through the colored cover glass like a chessboard.

German researchers are currently producing strip-shaped solar cells, which they glued together so that they overlap a few millimeters to form a larger module. This creates a uniform whole without interfering with gaps or visible contact lines. Kroyer concluded: "You can see from different angles that our MorphoColor coated wood panel photovoltaic modules still maintain a uniform impression."