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Fixed focus trough with divided concentrator

Cross section and path of rays in the fixed focus collector. Picture: DLR

This collector is a parabolic trough with segmented mirror surface. Due to this special arrangement of single mirror segments, the center of gravity and thus the rotation axis of the collector is shifted into the absorber tube axis. Therefore, the absorber tube is stationary while the mirror segments are tracking the sun (fixed focus parabolic trough – FFPT). The advantage of fixed absorber tube is that the connections of the collector rows in the solar field can be technically much simpler.

The concept was studied in two pre-studies at DLR, where the following advantages were to be found:

• No need for rotating ball joints
• Reduced wind load
• Stow position is possible in upside down position (less wear of the mirror surface, contamination and storm damage)
• Better optical performance by minimizing the length of the reflecting rays
• Reduced material use due to less wind load