Solar Fields of Concentrating Collectors

Based on the characteristics of individual collector units, a solar field has to be assembled which is sufficiently large to generate the required thermal power at a sufficiently high temperature. The heat transfer fluid is pumped through a solar field, transporting the heat from the collectors to the demand side heat exchanger or directly to the consumer. Additional optical losses may occur in a solar field due to mutual shading and blocking. Thermal losses, especially at nighttime, and hydraulic pressure losses to be overcome by pumping power, shall be minimized. Changes in the thermophysical properties of single-phase fluids as well as phase change of two-phase fluids have to be considered. The basics of solar thermal loop control are presented, boundary conditions for the operation and maintenance of the components are illustrated, and finally some line- and point-focusing systems are compared with respect to their operating characteristics.