Liquid crystal devices for photovoltaic systems

The power conversion efficiency, which is defined as the ratio of the output electrical power density to the incident light power density of the solar cell, is one of the most important parameters of a photovoltaic (PV) system. The efficiency depends on the photon flux density of the incident light, which changes frequently in different environment. For example, the solar cell in a solar power station receives the sunlight, which changes with the weather, season, and time; the solar cell on a mobile device may be used indoor and outdoor alternately. In order to preserve a static output of a solar cell in different environments, a tunable light modulator for keeping a static incident photon flux density is needed. Liquid crystal (LC) light modulators have been developed for years, which can be used to improve the PV systems. In this chapter, we introduce the PV systems with high and steady output by adopting electrically tunable LC light modulators. This concept may open a window to enhance the efficiency of CPV systems by using active optical elements.