U pipe solar collector solar keymark EN12975 Certificate:CCC,3C,CE,solar keymark can be installed with any angels U pipe solar collector solar keymark EN12975 Pressure U-pipe/Heat Pipe Solar Collector Introduction:For several years of research, our company has invented a new type of U-tube solar collector. The patent number is ZL 200820082791.7A U-type metal heat exchanger tube is streched into ...