Luminescent solar concentrators: From experimental validation of 3D ray-tracing simulations to coloured stained-glass windows for BIPV

Luminescent solar concentrators (LSC) are a promising technology for building integrated photovoltaics (BIPV) given the wide variety of forms and colours that can be realised. Given the flexibility of the technology, the use of ray-trace modelling is indispensable in the design, performance evaluation, and optimisation of LSCs. This work begins by comparing a three dimensional (3D) ray-trace model of an LSC with experimental results. The study includes 70 samples - both square and circular LSCs, containing five different fluorescent organic dyes (BASF Lumogen) each at seven different concentrations. The figure-of-merit used for performance evaluation was the average power density determined at the LSC edge sheet, measured using an optical fibre connected to a spectrometer. The results demonstrate that 3D ray-trace results gives good agreement with the experimental measurements, to within around ±5% within a wide concentration range (optical density=0.05-8) and a maximum difference of ±13%. The wide range of colours achieved is presented in a CIE chart. Overall, the validated experimental results give confidence in the use of modelling for future larger LSCs for BIPV. Therefore, based on these results and the colours achievable, a model of a stained-glass window is constructed and its performance throughout a solar day is simulated.