Solar heat collector

A solar heat collector comprising:

• means for absorbing solar radiation;
• means for transporting heat transfer fluid through said solar heat collector, said fluid being heated by said absorber means;
• an insulation for minimizing heat losses from said collector, said insulation exhibiting thermal stability at stagnation condition temperatures of about 400.degree. F., said insulation consisting essentially of:
• a first insulating layer having a relatively low temperature stability and a relatively low thermal conductivity:
• a second intermediate layer of metallic foil;
• a third insulating layer having a relatively high temperature stability and a relatively low thermal conductivity;
• means for fixedly securing said first, second, and third layers together, and
• means for housing said absorber means, said transporting means and said insulation, said insulation and said absorber means being relatively positioned to one another such that said third insulating layer is in closer proximity to said absorber means than said first insulating layer whereby said second intermediate layer of metallic foil prevents local buildup of heat throughout said insulation and prevents migration of low molecular weight material generated at said stagnation condition temperatures thereby preventing condensation of said low molecular weight material on cooler surfaces and maintaining a high thermal efficiency for the collector.