Integration of Color and Graphical Design for Photovoltaic Modules Using Luminescent Materials

Luminescent materials suitably embedded into the architecture of photovoltaic (PV) modules can increase the short-wavelength response and, thus efficiency, of nearly all in-production PV technologies. At the same time, visible-wavelength luminescence that escapes the modules due to its omnidirectional nature is perceived as color when it reaches the human eye. It is shown that this "lost" luminescence can be used for the application of aesthetical as well as functional coloration, while maintaining-or even increasing in favorable cases-the efficiency of commercial PV modules. Cadmium telluride (CdTe) and crystalline silicon (c-Si) minimodules were encapsulated with luminescent add-on layers. Performance enhancement of 0.4 mA/cm(2) is reported as the best result for a CdTe minimodule with a custom graphical design. Results on c-Si devices indicate that it is possible to use graphic designs, leading to only a small reduction in electrical output. Aspects and implications arising from the potential for aesthetical and functional coloration of commercial PV modules are discussed, together with technical challenges that need to be addressed.