Luminescent solar concentrators (LSCs) generally consist of transparent polymer sheets doped with luminescent species. Incident sunlight is absorbed by the luminescent species and emitted with high quantum efficiency, such that emitted light is trapped in the sheet and travels to the edges where it can be collected by solar cells. LSCs offer potentially lower cost per Wp. This paper reviews results mainly obtained within the framework of the Fullspectrum project. Two modeling approaches are presented, i.e., a thermodynamic and a ray-trace one, as well as experimental results, with a focus on LSC stability.

The reflection reducing properties of alkaline-etched multicrystalline wafers are investigated experimentally for high concentration saw-damage etching and low concentration texture etching. Saw-damage etch textures are too flat for multiple bounce reflectance in air, with only 1.6% of the multicrystalline wafer surface calculated to have facet tilt angles above 45°whereby double-bounce reflectance is guaranteed. Texture etching yields 3% lower reflectance in air, due to high angled ͑up to 54.7°͒ pyramidal structures on near ͑100͒ orientations, whereby 13% of the multicrystalline etch surface has tilt angles above 45°. However, under encapsulation, light is coupled more effectively into the silicon; reflectances for the saw-damage and texture-etched wafers compare only 7 and 5.5% higher, respectively, than upright pyramid textures on monocrystalline silicon͑100͒, compared to 18 and 15% higher in air. This is because a far larger proportion of the multicrystalline wafer ͑around 40% for the two etches͒ has tilt angles above 20.9°whereby escaping light is totally internally reflected at the glass-air interface. For texture etching, not only ͕111͖ planes are stable to etching but the whole range of ͕XXY͖ crystallographic planes between these and ͕110͖ orientations, contrary to the accepted texture etching theory.

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