This chapter provides an overview of the physical challenges and concepts for light management in solar modules, as well as established solutions and current and novel approaches to realize the ambitious goal of the International Technology Roadmap for Photovoltaic (ITRPV) roadmap. Focusing on the typical construction of the crystalline silicon solar modules, a description of the physical phenomena that determine the losses of a light beam on its path through the several layers of a module is provided. The physics of anti-reflection and light trapping/light redirection concepts is provided with the report on experimental and simulation techniques to assess the achievable progress under consideration of the real field situation, expressed in parameters like spectral distribution and varying incidence angle of sunlight, or diffuse lighting. The chapter discusses technological solutions that are already implemented, that are on the threshold to industrial use, and novel concepts currently under basic investigation