OPTI combines a commercial ray/wave optical modeling tool (CROWM) with a custom Python-based optimization engine, enabling simulation of optical stacks of near-unlimited complexity—including random pyramids and other scattering structures (size d > λ).

A Bayesian optimization backbone tunes the optical stack for optimal performance under any target spectrum (standard AM0 or AM1.5G, with custom options such as indoor PV) within user-defined parameter limits. For example, optimizing a fully textured perovskite-silicon tandem—starting from four random thickness sets with only the c-Si wafer thickness fixed—reached over 95% of the Lambertian limit within 100 iterations. The model can also verify established physical rules, such as the λ/4 principle.

For users with additional material thermal-coefficient data, OPTI can extend to combined optical and equivalent electrical modeling, predicting and optimizing outdoor energy yield.