The COLOUR2FOIL project is developing a flexible and efficient solution for the production of coloured photovoltaic (PV) modules. The interlayer is manufactured using a roll-to-roll process and consists of a combination of structural colour thin-film stacks and textured surfaces. Since the product is intended for coloured PV modules for building integration, the reliability required for a long product lifespan is ensured through rigorous material testing and high-acceleration stress tests. Furthermore, a method for simplified angle-dependent colour evaluation based on a camera-based system for both indoor and outdoor applications is being developed.
Most colour technologies currently used in PV modules either exhibit high transmission losses due to absorption in pigment-based layers or significant iridescence when based solely on textured colours—both of which make consistent matching to conventional building materials difficult. The technology developed in this project minimizes iridescence by using a textured substrate on which the structural colour thin-film stacks are conformally deposited.
By developing this solution directly for roll-to-roll production processes, the final product will be extremely flexible in terms of size, transmission losses will be minimized to a maximum of 15% by utilizing the efficiency of textured paints, and a largely uniform appearance will be achieved that is indistinguishable from that of conventional building materials such as clay roof tiles. Accelerated stresses typical of PV modules, such as humid heat, thermocycling, and UV irradiation, combined with advanced characterization methods, will ensure good material compatibility and low degradation.
To address the second major challenge – documenting angle-dependent appearance variations of PV modules and matching their colour to conventional building materials – a camera-based colorimetric imaging system for indoor and outdoor use is being developed. Three different approaches for adapting indoor measurement methods to outdoor conditions are being investigated and compared with reference data from a goniospectrophotometer. Furthermore, a methodology for documenting and comparing relevant parameters of the angle-dependent appearance is being developed. As a flexible, coloured interlayer, the developed product can be easily integrated into any type of PV module. This enables the aesthetic integration of PV into buildings, thus accelerating the use of renewable energy in buildings. This supports the goals of the EU Directive on the overall energy efficiency of buildings and the EU’s renovation initiative. Furthermore, the market for coloured PV modules for buildings is expected to grow significantly in the coming decades, offering substantial economic opportunities for the participating industrial partners.
The project is being carried out by an international consortium of universities, a research institute, and industrial partners from Austria, Denmark, and Finland, who combine expertise in modeling, manufacturing, material analysis, testing, and characterization.
National funding: FFG (Advanced Materials, M-ERA.NET Call 2025)
Project consortium:
Lead: Technical University of Denmark, DTU Electro
Project partners:
University of Southern Denmark; Mads Clausen Institute
OFI, Österreichisches Forschungsinstitut für Chemie und Technik
