What is the difference between vacuum tube collectors and flat plate collectors?
With flat plate glazed collectors the absorbers are fitted in a box closed by a pane of glass (88 % market share in 2006 in Europe). Vacuum tube collectors – which are the dominating technology in China (89 % market share in 2006) – have the absorber placed within a succession of evacuated glass tubes. Generally speaking, the advantage of vacuum tubes is a higher efficiency (less space required for the collector on the roof) and higher temperatures (necessary for process heat and some solar cooling technologies). The disadvantage: The vacuum tubes produced in Europe are more expensive than the flat plate collectors but in some incentive schemes like in Germany they receive the same grants as the flat plate collectors. In China, some locally produced vacuum tube collectors have a poor quality performance, flat plate collectors are seen as high-quality products.
