Five different substrates were tested for their suitability for use as waveguides for luminescent solar concentrators for solar energy applications. The function of such a waveguide is to collect light and to transport it towards a solar cell. In this study the influence of the material of the waveguide on the light emission of the system was investigated. It was determined that the material chosen for the waveguide was not as important as the presence or absence of additives in the waveguide itself. This indicates that economic factors (material cost) and secondary properties such as refractive index, outdoor lifetime and weight are at least as important in the waveguide selection as the nature of the materials used. © 2009 Elsevier B.V. All rights reserved.