Increasing the area of a white scattering background can increase the power output of a luminescent solar concentrator

Abstract

Luminescent solar concentrators (LSCs) have the potential of converting solar energy into electricity more cheaply than a standard photovoltaic (PV) panel. LSCs are thin plates of plastic or glass that contain fluorescent material throughout the plate or in a thin film adhered to the surface. The fluorescent material absorbs sunlight and its fluorescence is concentrated onto PV cells along the edges of an LSC using total internal reflection. Some light is able to pass through the LSC and does not reach the PV cells. A white diffusive scattering surface, or white background, is able to scatter this light back into the LSC for another chance of reaching the PV cells. The results of our experimental and theoretical research reveal that using white backgrounds larger than the area of the LSC can further increase its power output. Larger backgrounds produce more power, but with diminishing returns. An optimal air gap between the LSC and a larger white background is required to achieve maximum benefit. The size of this optimal air gap increases as the area of the white background increases. The predictions of our theoretical model agree with our experimental results for the relative performance of these larger white backgrounds with respect to their size and separation from the LSC. Our experimental results show an optimal air gap of 10.7 cm separating an LSC from a white background with an area 16 times larger than the LSC. In this configuration, the LSC produced 28% more power than the maximum power output of the LSC using a white background of the same area, and 54% more power than the LSC with no white background present.