Evacuated Tube Collectors are a light-weight and highly efficient alternative to Glazed Flat Plate Collectors. While in general they perform similarly to a high quality Flat Plate Collector they are especially efficient at times of low Solar Gain – winter months, mornings and late afternoons. This can be advantageous when designing a Solar Thermal system with Space Heating contribution.

Evacuated Tube Collectors are made up of a “Heat Pipe” which is attached to highly absorbent fins and protected from the elements by an Evacuated or “Vacuum” tube. Since heat transfer is not possible through a vacuum the result is the highly efficient harnessing and transmittance of the sun’s radiation.

When comparing Flat Plate Collectors and Evacuated Tube Collectors the actual aperture are of each must be taken into account. This is the area of the collector that absorbs Solar Radiation excluding the frame of the collector or the space between tubes.