Evacuated Tube Heat Pipe Technology
Simpler, more efficient and more powerful.
The increased efficiency of vacuum tube solar collectors is obtained by preventing re-radiation from the absorber surface.
Effectively vacuum tubes are long, thin, Thermos flasks. In the same way as Thermos keep hot drinks hot, the vacuum tube drastically reduces the heat lost from the heat pipe, which has been heated by the sun, to almost zero.
The older flat plate collectors however suffer tremendous losses particularly when used in a cold air environment. In cold air a flat plate will re radiate a large proportion of the energy collected back into the atmosphere.
The picture below is an infrared thermal image of two collectors side by side. On the left of the image is a flat plate collector and on the right a vacuum tube collector.
On the left the losses from the flat plate are clearly evident from the range of colours displayed.
The red and yellow sections indicates the hottest area and the green and blue areas the cooler side where cold water is entering the collector.
So whilst a flat plate may perform adequately in the summer months in the winter performance is markedly lower.