How to decide the alignment of the parabolic trough collector according to the local latitude

摘要

Parabolic trough is a very attractive technology for using solar energy.The optical loss of the parabolic trough is related with the local latitude,either for the eastwest (E-W) or north-south (N-S) orienting mounted troughs.Based on the basic transform between solar coordinate and the earth surface coordinate,the cosine loss of for both the E-W and N-S parabolic troughs are calculated,according to the local latitude.The results indicate that,while the optical loss for E-W trough almost keeps as a constant of 16％,the optical loss for N-S system is highly dependent on the local latitude.Thus the critical latitude of 37.35° is obtained.For the place where its latitude is lower than 37.35°,the parabolic trough should be mounted along E-W orientation,otherwise it should be positioned in N-S orientation,to obtain the least cosine loss.