Thermoelectrics: Direct solar thermal energy conversion

The solar energy conversion process can be envisioned, where a high-efficiency solar collector turns the sunlight into heat that is then transformed by the thermoelectric devices into usable electricity. It can be stored in a thermal bath and transformed into electricity through thermoelectrics when the sun not shine. A thermoelectric power conversion device operates between 500° and 30° and yield about 50% of the Carnot efficiency. The thermal-to-electric energy conversion is a solid-state conversion process, which has no mechanical parts, and provides long-term stability. The conversion efficiency is related to a quantity called the figure of merit, which is determine by three main parameters, such as the thermopower, electrical resistivity, and the thermal conductivity. A significant difference in temperature is needed to generate sufficient energy, which can be supply through the infrared region of the solar spectrum.