Luminescent Solar Concentrators for Building Integrated Photovoltaics: Opportunities and Challenges

This review examines the application of luminescent solar concentrators (LSCs) for building integrated photovoltaics (BIPV), both in terms of opaque façade elements and as semi-transparent windows. Many luminophores have been developed for LSC applications, and their efficiencies examined in lab-scale (< 25 cm2) devices. This review illustrates, using ray-tracing simulations, the technical challenges to maintaining efficiency when scaling these energy conversion devices to pilot- (1000 cm2) and commercial-scale (100000 cm2) modules. Based on these considerations, ambitious but feasible target efficiencies for LSCs based on ideal quantum dot (QD) luminophores are suggested as follows – for opaque and semi-transparent (50% average visible transmission), respectively: i) 11.0% and 5.5% for lab-scale devices; ii) 10.0% and 5.0% for pilot-scale modules; and iii) 9.0% and 4.5% for commercial-scale modules. It is worth noting though, that the QD design requirements – particularly with regard to the overlap integral between the absorption and emission spectrum – becomes very critical as the LSC area increases. Whereas it is difficult to see opaque LSCs successfully competing against standard flat-plate photovoltaic modules for building integration, the application of semi-transparent LSCs as power-generating window elements has potential. Therefore, an economic analysis of the inclusion of LSCs into commercial glazing elements is presented and the potential for novel technologies – such as down-conversion (quantum-cutting) and controlling the direction of emitted light – to move this technology towards application is also discussed.