... ,anti-freeze, high efficient for Split pressure system and project heating Features of heat pipe solar collector panel ... , efficient, twin-glass solar tubes heat pipe.2) Copper heat pipes for rapid heat transfer. 3) Low maintenance effort. ... 35 Centigrade Degree7) Tested according to EN12975-2,with Solarkeymark Certificates.8) Guaranteed min. power output ... heating Tubular solar collector with heat pipe