Colored Solar Modules: Improved Energy Balances

Placing solar modules on a flat roof has two key advantages: firstly, this is where solar radiation is at its highest. Secondly, they do not detract from the overall aesthetic appearance of a building. If additional space is required for generating solar power, such as sloping roofs or even facades, the design options become more limited. This raises the question of developing aesthetically appealing and modifiable solar modules that allow a high degree of design freedom in terms of color and other design requirements while minimizing color-related energy yield losses.

The joint project “Light management and manufacturing concepts for colored photovoltaic modules in building facades” (Color PV) by Fraunhofer CSP, Hohenstein Isolierglas GmbH, and Kogu Print & Werbetechnik GmbH & Co. KG addressed this issue. The aim was to enable the flexible display of different single-color or multi-color designs on solar modules with a wide range of colors and relatively high resolution, so that even photorealistic images could be displayed. In contrast to most technologies investigated to date for coloring solar modules, which use spectrally selective coatings and thus only allow homogeneous, single-color surfaces with a very limited choice of colors, the project partners relied on digital printing processes and multicolor printing for a wide range of colors as well as individual, semi-transparent color prints (Kogu Print). In addition, the project demonstrated the potential of special interference-based inks with high light transmission for colored PV modules and optimized various structuring and lamination processes. Structures in the laminates (HIG) were used to improve light guidance.

"With the development of a colored, digitally printed facade solar module front with high light transmission in the relevant spectral range, we are opening up new possibilities for facade design. Photovoltaic module manufacturers and their suppliers can use this to develop new product solutions that can be sold on the global market for building-integrated photovoltaics," says Charlotte Pfau, project manager at Fraunhofer CSP. What makes this project special is that it covers the entire value chain, from film and glass processing to digital printing and solar module production.