Different simulation techniques have been used to model LSCs. Mathematical models have accompanied experimental results since the concept was proposed in the 1970s, and considered standard optical events such as absorption, photoluminescence, light trapping by the waveguide, and reabsorption of emitted photons. More complex optical models have also been developed, which have simulated both single-and four-edge LSCs, coated cylindrical LSCs, anisotropic luminescence, stimulated emission, collector shape, and two-layer LSCs. Thermodynamic LSC models are another class initially proposed in 1980 by Yablonovitch, which consider rate balance equations applied to volume elements that are then integrated over the entire LSC to obtain a model of performance. The most recent thermodynamic models include significant incident flux absorption, spectral overlap to account for re-absorption, and waveguide parasitic absorption, and have been applied to planar LSC slabs, modules, and stacks. However, a limitation of these approaches is that they are not easily applied to new geometries: optical models must be derived independently and cannot be easily generalized, and since the thermodynamic model requires volumetric integration and a uniform distribution of luminophores, it is similarly inflexible.