1. A solar energy module for converting solar radiation to thermal energy, the module comprising:(a) a glass plate;
(b) a transparent insulation;
(c) a sealed enclosure having a fixed volume available to an enclosed gas inside said sealed enclosure said sealed enclosure having a duct fluidly connecting said fixed volume with a variable volume vessel outside said sealed enclosure, said variable volume vessel is for varying a volume available to said enclosed gas, said volume varying in accordance with changing temperature of said enclosed gas;
(d) an absorbing element configured to absorb the solar radiation transmitted via said glass plate then via said transparent insulation, said absorbing element inside said sealed enclosure, said absorbing element in thermal contact with said enclosed gas;
(e) at least one liquid pipe thermally coupled to said absorbing element; and
(f) at least one heat pipe, wherein a vaporization volume of said heat pipe is inside said sealed enclosure and is thermally coupled to said absorbing element and wherein a condensation bulb of said heat pipe is external to the solar energy module,
said transparent insulation including thermal convection suppression, suppressing convective heat transfer between said glass plate and said absorbing element,
thereby the solar radiation penetrates said glass plate, then penetrates said transparent insulation and is absorbed by said absorbing element, said enclosed gas is heated in said fixed volume, said enclosed gas flows from said fixed volume via said duct to said variable volume vessel, said variable volume vessel varies to increase said volume available to said enclosed gas inside said sealed enclosure, thus keeping a pressure of said enclosed gas within structurally tolerable limits of the solar energy module.