A silica aerogel having a mean pore size less than 5 nm with a standard deviation of 3 nm. The silica aerogel may have greater than 95% solar-weighted transmittance at a thickness of 8 mm for wavelengths in the range of 250 nm to 2500 nm, and a 400 C. black-body weighted specific extinction coefficient of greater than 8 m.sup.2/kg for wavelengths of 1.5 m to 15 m. Silica aerogel synthesis methods are described. A solar thermal aerogel receiver (STAR) may include an opaque frame defining an opening, an aerogel layer disposed in the opaque frame, with at least a portion of the aerogel layer being proximate the opening, and a heat transfer fluid pipe in thermal contact with and proximate the aerogel layer. A concentrating solar energy system may include a STAR and at least one reflector to direct sunlight to an opening in the STAR.

A silica aerogel having a mean pore size less than 5 nm with a standard deviation of 3 nm. The silica aerogel may have greater than 95% solar-weighted transmittance at a thickness of 8 mm for wavelengths in the range of 250 nm to 2500 nm, and a 400 C. black-body weighted specific extinction coefficient of greater than 8 m.sup.2/kg for wavelengths of 1.5 m to 15 m. Silica aerogel synthesis methods are described. A solar thermal aerogel receiver (STAR) may include an opaque frame defining an opening, an aerogel layer disposed in the opaque frame, with at least a portion of the aerogel layer being proximate the opening, and a heat transfer fluid pipe in thermal contact with and proximate the aerogel layer. A concentrating solar energy system may include a STAR and at least one reflector to direct sunlight to an opening in the STAR.

A silica aerogel having a mean pore size less than 5 nm with a standard deviation of 3 nm. The silica aerogel may have greater than 95% solar-weighted transmittance at a thickness of 8 mm for wavelengths in the range of 250 nm to 2500 nm, and a 400 C. black-body weighted specific extinction coefficient of greater than 8 m.sup.2/kg for wavelengths of 1.5 m to 15 m. Silica aerogel synthesis methods are described. A solar thermal aerogel receiver (STAR) may include an opaque frame defining an opening, an aerogel layer disposed in the opaque frame, with at least a portion of the aerogel layer being proximate the opening, and a heat transfer fluid pipe in thermal contact with and proximate the aerogel layer. A concentrating solar energy system may include a STAR and at least one reflector to direct sunlight to an opening in the STAR.

The invention relates to a product for heating comprising at least one heating unit (2), which comprises a base material layer with an emission reducing structure on top of said an energy converting structure, combined together to form a selective absorber layer on at least one of the sides of the base material layer, at least one insulation layer (4, 5, 6, 7) of transparent flexible material located on the heating unit (2), which heating unit and the at least one insulation layer on the heating unit (2) of the product (1) are attached to each other air-tightly on the sides such that between at least some of the layers at least one closed air pocket (10, 11) is formed, characterized in that the content to be heated by the product is located below to the base material of the heating unit of the product (1), that temperature of the content of the product (1) will be 90 C.-160 C., as result of the placing the product (1) exposed to radiation of selected wavelengths, and that the energy converting structure in the selective absorber layer has an absorption factor (aS) of a minimum of 0.9 and the emission reducing structure has an emission factor (E) of a maximum of 0.1 and that ratio between the absorption factor (aS) and the emission factor (E) is equal or higher than 9 and that when the selective absorber is exposed to wavelengths ranging from 350 nm to 4000 nm, the energy converting structure converts the wavelengths to thermal energy ranging from 4000 nm to 40.000 nm and the emission of thermal energy is reduced by the emission reducing structure and the contained energy is being used for heating the content of the product (1).

The invention relates to a product for heating comprising at least one heating unit (2), which comprises a base material layer with an emission reducing structure on top of said an energy converting structure, combined together to form a selective absorber layer on at least one of the sides of the base material layer, at least one insulation layer (4, 5, 6, 7) of transparent flexible material located on the heating unit (2), which heating unit and the at least one insulation layer on the heating unit (2) of the product (1) are attached to each other air-tightly on the sides such that between at least some of the layers at least one closed air pocket (10, 11) is formed, characterized in that the content to be heated by the product is located below to the base material of the heating unit of the product (1), that temperature of the content of the product (1) will be 90 C.-160 C., as result of the placing the product (1) exposed to radiation of selected wavelengths, and that the energy converting structure in the selective absorber layer has an absorption factor (aS) of a minimum of 0.9 and the emission reducing structure has an emission factor (E) of a maximum of 0.1 and that ratio between the absorption factor (aS) and the emission factor (E) is equal or higher than 9 and that when the selective absorber is exposed to wavelengths ranging from 350 nm to 4000 nm, the energy converting structure converts the wavelengths to thermal energy ranging from 4000 nm to 40.000 nm and the emission of thermal energy is reduced by the emission reducing structure and the contained energy is being used for heating the content of the product (1).

A protective transparent enclosure (such as a glasshouse or a greenhouse) encloses a concentrated solar power system. The concentrated solar power system includes one or more solar concentrators and one or more solar receivers. Thermal power is provided to an industrial process, electrical power is provided to an electrical distribution grid, or both. In some embodiments, the solar concentrators are parabolic trough concentrators with one or more lateral extensions. In some embodiments, the lateral extension is a unilateral extension of the primary parabolic trough shape. In some embodiments, the lateral extensions are movably connected to the primary portion. In some embodiments, the lateral extensions have a focal line separate from the focal line of the base portion. In some embodiments, the greenhouse is a Dutch Venlo style greenhouse.

A solar vapor generator includes an absorber to absorb sunlight and an emitter, in thermal communication with the absorber, to radiatively evaporate a liquid under less than 1 sun illumination and without pressurization. The emitter is physically separated from the liquid, substantially reducing fouling of the emitter. The absorber and the emitter may also be heated to temperatures higher than the boiling point of the liquid and may thus may be used to further superheat the vapor. Solar vapor generation can provide the basis for many sustainable desalination, sanitization, and process heating technologies.

A solar thermal absorber element (100) includes a cover glass (110) and a highly selective vacuum coated roll-bond absorber (120) including heat transport tubes (126). The element further including a thermoplastic sealing (130) configured to attach the cover glass and the roll-bond absorber to each other so that there is a distance (h) between the cover glass and the roll-bond absorber, and a sealed space (134), which is formed by the cover glass, the roll-bond absorber, and the thermoplastic sealing and which is filled up with a low thermal conductive gas (136).

A protective transparent enclosure (such as a glasshouse or a greenhouse) encloses a concentrated solar power system. The concentrated solar power system includes one or more solar concentrators and one or more solar receivers. Thermal power is provided to an industrial process, electrical power is provided to an electrical distribution grid, or both. In some embodiments, the solar concentrators are parabolic trough concentrators with one or more lateral extensions. In some embodiments, the lateral extension is a unilateral extension of the primary parabolic trough shape. In some embodiments, the lateral extensions are movably connected to the primary portion. In some embodiments, the lateral extensions have a focal line separate from the focal line of the base portion. In some embodiments, the greenhouse is a Dutch Venlo style greenhouse.

A solar heat collector includes a plurality of heat collecting tubes connected in series. The heat collecting tubes each include: a heating-medium circulating tube through which a heating medium circulates; a glass tube that covers an outer peripheral surface of the heating-medium circulating tube and forms an annular space between the glass tube and the heating-medium circulating tube; and a getter member that adsorbs a gas that exists within the annular space. The heat collecting tube on a downstream side of the heating medium includes a larger number of the getter members than the heat collecting tube on an upstream side of the heating medium.