Book excerpt: Three dimensional (3D) optical geometries are becoming more common in the literature and lexicon of solar cells. Three Dimensional Solar Cells Based on Optical Confinement Geometries describes and reveals the basic operational nuances of 3D photovoltaics using three standard tools: Equivalent Circuit Models, Ray Tracing Optics in the Cavity, and Absorber Spectral Response. These tools aide in understanding experimental absorption profile and device parameters including Jsc, Voc, Fill Factor, and EQE. These methods also apply to individual optical confinement geometry device, integrated optical confinement geometry device, and hybrid optical confinement geometry device. Additionally, this book discusses the importance of these methods in achieving the goal of high efficiency solar cells and suggests a possible application in large-scale photovoltaics business, like solar farms.