Upconversion (UC) constitutes an approach to increase the efficiency of solar cells by making use of the otherwise non-utilized sub-bandgap photons. Photonic structures can influence the properties of luminescence phenomena. This is of particular interest when tuning the properties of non-linear luminescence processes, such as photon UC, thus increasing the UC efficiency. Tuning the photonic structure design to maximize UC enhancement requires a careful design optimization, for which an adequate modeling framework has been missing throughout literature. The analysis of this work covers the development of a comprehensive modeling framework to understand the photonic effects on the UC dynamics, the experimental realization of optimized photonic upconverters in high precision and the validation of the model's predictions in large scale parameter scans. The validated modeling framework now enables a precise optimization of photonic structure designs for various upconverting materials and target applications.