... riser tubes 4.pressure solar panel collectorFlat plate collectors are the most common solar collectors for use in solar water-heating systems ... 4±2%, stable performance, life span 50years;(2)Special design structure, 360°heat transfer, excellent thermal conductivity;(3)Optical ... shaped in the cavity,reduce heat loss;(4)Integrated frame design, nice outlook, stable structure, easy to install;(5) ...