Evacuated Tube Collector
How does an Evacuted Tube
Vacuum tube collectors use heat pipes for their core instead of passing liquid directly through them. Evacuated tubes are composed of multiple tubes each containing an absorber plate fused to a heat pipe. The heat from the hot end of the heat pipes is transferred to the transfer fluid (water or an anti-freeze mix—typically propylene glycol) of a domestic hot water or hydronic space heating system in a heat exchanger called a "manifold". The manifold is wrapped in insulation and covered by a sheet metal or plastic case to protect it from the elements.
The vacuum that surrounds the outside of the tube greatly reduces convection and conduction heat loss to the outside. In those cases where very hot water is desired, for example commercial process water evacuated tube collectors are often the best solution. The high temperatures that can occur may require special system design to avoid or mitigate overheating conditions.
Solar Rating and Certification Corporation
The Solar Rating and Certification corporation currently administers a certification, rating, and labeling program for solar collectors and a similar program for complete solar water heating systems. Collector testing apparatus SRCC’s certification program operating guidelines, test methods and minimum standards, and rating methodologies require the performance of nationally accepted equipment tests on solar equipment by independent laboratories which are accredited by SRCC. The test results and product data are evaluated by SRCC to determine the product’s compliance with the minimum standards for certification and to calculate the performance ratings. Equipment which has been certified and rated by SRCC is required to bear the SRCC certification label which shows the performance rating for that product. In addition, each certified product is published by SRCC in a directory. Each product’s directory listing contains information on the product’s material and specifications as well as the certified thermal performance.read more