Fraunhofer CSP is developing a retrofit coloring concept for commercially available PV modules without altering the original manufacturing
The COLIPRI project applies ceramic-based color systems and digital printing to minimize shading and optical losses
The project aims to retain at least 75% of the efficiency of an unprinted reference module while ensuring long-term stability
Solar PV is widely deployed across utility-scale and rooftop applications. In urban environments, however, building-integrated photovoltaics (BIPV) have yet to realize their full potential. Aesthetic integration is a key barrier to this adoption.
Conventional high-efficiency modules are typically designed in uniform dark tones, usually black. Although optimized for light absorption and performance, this design restricts architectural flexibility. For façade integration, heritage buildings, and premium urban projects, architects often require customized colors and visually appealing surfaces. However, currently available colored solar modules are either expensive or suffer from significant efficiency losses when color is introduced, making them economically challenging to integrate.
Fraunhofer Center for Silicon Photovoltaics CSP initiated project COLIPRI to address the aesthetic limitations faced in buildings, balconies, and façades. The aim of project is to make solar modules customizable in color for buildings and façades while preserving electrical performance.
The project focuses on developing a retrofittable coloring approach that does not require changes to the original module manufacturing process. Instead of redesigning modules at the factory stage, digitally printed frontsheets or cover glass are produced separately and later laminated onto standard solar modules. This allows the use of low-cost, mass-produced modules while adding customized color layers without structural modification.
The research focuses on ceramic-based color systems and advanced digital printing technologies. A glass-ceramic matrix is being developed to ensure the reliability and stability of the colored layer. Spectrally selective pigments and optimized printing patterns are used to reduce optical losses and shading effects. A key objective of the project is to retain at least 75% of the efficiency of an unprinted reference module. In addition to performance, the colored glass layers must withstand environmental stress such as UV exposure, temperature cycling, and moisture ingress under real operating conditions.
In parallel, different lamination and module assembly approaches are being evaluated. These include configurations based on standard glass, thin glass, and polymer films. The solutions are being adapted for specific applications such as façades, roofs, and balcony modules.
The project also includes the development of measurement methods to quantify color impact, glare behavior, and resulting efficiency losses, including angular dependency under different operating conditions. In addition, a simulation approach is being developed to estimate expected performance losses based on print design and module layout.
“If photovoltaics are to become part of our built environment, they must be practically adaptable in design - without causing excessive efficiency losses,” says Dr. Charlotte Pfau, project manager at Fraunhofer IMWS.
Fraunhofer CSP is responsible for the design and evaluation of the colored retrofit solutions. This includes optimization of printing grids and optical layer configurations, laboratory-scale lamination testing, and performance characterization under UV and environmental stress conditions.