An important solar tube component is the getter. This is a barium layer which is applied to the internal side of the tube after the vacuum has been created. In this way, the vacuum is additonally protected from air / foreign molecules and a defective tube will be indicated immediately by a white colouration of the getter.
The OEG 4flex® heat pipe solar tube has the largest getter all across the market and a TiNOx coating which is supposed to absorb 96% of the incident solar energy and emits only 4% back to the environment. This is currently the best available coating for solar collectors.
Other solar tubes in the market often only have a small getter of unspecified length and the barium layer is difficult to control.
