Adaption of Collector Orientation for Parabolic Trough Plants in High Latitude Regions

Abstract

North-South (N-S) orientation of trough collectors is a common design for parabolic trough plants, which typically provides the maximum annual production. However, such orientation is neither the only one option nor an appropriate solution, especially in high latitude like 40º or higher regions. In actual practises, significant monthly production difference is obtained using N-S orientation due to the so-called “cosine” effect. In this paper, East-West (E-W) orientation option is analysed using System Advisor Model developed by NREL. Results show that annual thermal energy incident on receiver tubes can be increased when using E-W orientation in high latitude regions. The higher the latitude, the more the energy gain. Besides, a more uniform monthly thermal energy incident on receiver tubes can be also obtained for E-W orientation, which leads to more stable monthly outputs of the plant, as well as higher utilization rate of the thermal energy storage system. Further analysis shows that row distance between collectors can be reduced at the same cost of incident solar energy losses, resulting in an appreciable savings of land, piping, insulation, HTF inventory, etc., and finally CAPEX and OPEX. Extensive study indicates collector orientation can be along arbitrary direction, and final decision shall be made considering specific site conditions and local energy needs. In conclusion, N-S orientation of collectors is not always the only option for parabolic trough plants. E-W or other orientation rather than N-S orientation shall be carefully analyzed, especially in 40º or higher latitude regions.