In each vacuum tube there is a U pipe with direct flow-through that is connected to the header pipe inside manifold. This U pipe is seamed in an aluminum heat transfer fin in the interior of vacuum tube that transmits the heat from the interior tube to the U pipe.
Solar radiation permeates the outer glass tube and is captured on the outside of inner glass tube by highly selective sputter layer. The captured solar radiation is transmitted to flush-contact aluminum shield and then copper pipe filled with heat transfer fluid. The 360° Aluminum heat transfer fin assures the fastest energy transfer.