Evacuated solar receiver utilizing a heat pipe

A solar receiver in which a rod of high thermal conductivity is mounted in an evacuated envelope so as to receive thermal energy and which is coated with a selective absorbing surface so as to minimize radiation has a heat transfer end which is surrounded by a suitable material such as pyroceram or porcelain or other suitable material which extends into a container from which the heat produced by the solar energy is removed. The glass envelope surrounding the rod is attached by welding to the pyroceram cylinder and the heat transfer cavity is connected with an O-ring to the pyroceram cylinder so as to provide a liquid seal.