What is an evacuated tube collector?
Evacuated tube collectors consist of rows of parallel transparent glass tubes, each containing an absorber tube. Newer-technology evacuated tube collectors used to be more expensive than flat-plate collectors but costs have dropped as production increased, especially in China. Evacuated tubes are fragile, but they have a number of significant advantages: • The collector efficiency remains high in cloudy conditions and low temperatures. • The circular tube means that the sun is shining directly on the absorber for most of the day. • Evacuated-tube collectors have the ability to heat water to higher temperatures than flat plate collectors. • Evacuated-tubes can be added or removed as hot-water needs change.
