Evacuated tube solar collectors could look like a bunch of pipes or tubes connected to a metal frame. It goes beyond that. Evacuated solar tube collectors are a very efficient type of solar collector because each tube work almost the same as a vacuum flask. All the tubes are empty or evacuated, however, they collect the sun’s heat and also effectively traps the thermal energy inside. The trapped heat is transferred to the manifold which is usually at the top of the evacuated tubes. In the manifold, heat transfer liquid or fluid, heats up and transfers the heat to the hot water storage tank. What makes evacuated tube collectors more efficient? Heat does not escape as easily from evacuated solar tube collectors, unlike flat panel collectors. The only downside about evacuated tube collectors are, flat panel collectors are much more affordable than these evacuated tube collectors.