A method for manufacturing a vacuum-tight envelope for a vacuum solar thermal panel includes: joining edge to edge a first metal strip to a second metal strip in order to form a bi-metal strip, and then joining together the opposite ends of said bi-metal strip in order to form a closed loop; after said joining step, forming said first metal strip into a peripheral frame and said second metal strip into a peripheral belt; after said joining and forming steps, sealing the free edge of the peripheral belt to a glass front plate; after said joining and forming steps, joining a metal bottom plate to the peripheral frame.

A heat receiver tube for absorbing solar energy and for transferring absorbed solar energy to a heat transfer fluid which can be located inside of at least one core tube of the heat receiver tube is provided. The core tube includes a core tube surface with at least one solar energy absorptive coating for absorbing solar radiation. The core tube is enveloped by at least one enveloping tube. The enveloping tube includes at least one enveloping tube wall which is at least partly transparent for the solar radiation. The enveloping tube wall includes at least one inner enveloping tube surface. The core tube and the enveloping tube are coaxially arranged to each other such that an inner heat receiver tube space is formed which is bordered by the core tube surface and the inner enveloping tube surface.

A solar heat collection apparatus heats a heating medium flowing through a heat collecting tube by collecting sunlight in the heat collecting tube using a curved surface mirror. The heat collecting tube includes an inner tube through which the heating medium flows, an outer tube provided on an outer side of the inner tube, and a bellows, a flange, and a cylinder member connecting the inner tube to the outer tube. An insulating space is formed between the inner tube and the outer tube, and an exhaust hole that communicates with the insulating space is formed in the flange. The exhaust hole is sealed by a sealing member welded to the flange. As a result, damage to the outer tube can be prevented, and heat collecting tubes can be more easily connected to each other in the lengthwise direction.

The invention relates to a heliostat sub-assembly and to a method of forming such a sub-assembly. The method of mounting a concave mirror to a supporting structure of a heliostat includes the steps of bonding a plurality of risers at predetermined spaced intervals to a rear face of the mirror, each riser having a bonding pad and a stem extending from the bonding pad, and applying a predetermined concave curvature to the mirror by conforming the front face of the mirror with a convex forming jig or die. The supporting structure and curved mirror are then aligned, and the supporting structure is clinched to the stems of the risers when the curved mirror is conformed with the forming die. The riser stems may be coupled to the bonding pads via multi-axial joint assemblies to enable limited multi-pivotal movement of the stems relative to the bonding pads to facilitate alignment of faces of the stems with the faces of the ribs defined by webs, and relative expansion and contraction of the mirror and supporting structure, the overlap between the riser stems and the webs being sufficient to accommodate clinching with variations in curvature of the glass sheet.