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 solar thermal system is provided. The system comprises at least one solar thermal collector for heating a heat transfer fluid (HTF); and at least one conduit for transporting the HTF into and out of the at least one solar thermal collector; wherein said at least one conduit is of a foam or plastics material.

A solar thermal system is provided. The system comprises at least one solar thermal collector for heating a heat transfer fluid (HTF); and at least one conduit for transporting the HTF into and out of the at least one solar thermal collector; wherein said at least one conduit is of a foam or plastics material.

A localized heating structure includes a spectrally-selective solar absorber, that absorbs incident solar radiation and reflects at wavelengths longer than 2 m, with an underlying heat-spreading layer having a thermal conductivity equal to or greater than 50 W/(mK), a thermally insulating layer, adjacent to the spectrally-selective solar absorber, having a thermal conductivity of less than 0.1 W/(mK), one or more evaporation openings through the spectrally-selective solar absorber and the thermally insulating layer, and an evaporation wick, disposed in one or more of the evaporation openings in the thermally insulating layer, that contacts liquid and allows the liquid to be transported from a location beneath the thermally insulating layer through to the spectrally-selective solar absorber in order to generate vapor from the liquid. The thermally insulating layer is configured to have a density less than the liquid so that the localized heating structure is able to float on the liquid.

A localized heating structure includes a spectrally-selective solar absorber, that absorbs incident solar radiation and reflects at wavelengths longer than 2 m, with an underlying heat-spreading layer having a thermal conductivity equal to or greater than 50 W/(mK), a thermally insulating layer, adjacent to the spectrally-selective solar absorber, having a thermal conductivity of less than 0.1 W/(mK), one or more evaporation openings through the spectrally-selective solar absorber and the thermally insulating layer, and an evaporation wick, disposed in one or more of the evaporation openings in the thermally insulating layer, that contacts liquid and allows the liquid to be transported from a location beneath the thermally insulating layer through to the spectrally-selective solar absorber in order to generate vapor from the liquid. The thermally insulating layer is configured to have a density less than the liquid so that the localized heating structure is able to float on the liquid.

A new and innovative hard ceramic coating having refractory properties is provided. The ceramic coating may be used as a replacement for refractory materials. As opposed to polymer-based coatings that are sacrificial when exposed to extreme temperatures, the ceramic coating is a non-sacrificial, fully inorganic (e.g., free of organic components) coating that resists many thermal cycles. The ceramic coating is also thinner and lighter than conventional refractory materials the ceramic coating can replace. The ceramic coating demonstrates advantageous thermal insulation properties (e.g., low thermal conductivity) over a wide range of temperatures and when applied with minimal thickness. The ceramic coating also demonstrates high emissivity, low thermal conductivity, and high resistance mechanical properties, which are all desirable properties for use as a thermally insulating replacement coating for refractory materials.

A solar thermal system is provided. The system comprises at least one solar thermal collector for heating a heat transfer fluid (HTF); and at least one conduit for transporting the HTF into and out of the at least one solar thermal collector; wherein said at least one conduit is of a foam or plastics material.

A solar thermal system is provided. The system comprises at least one solar thermal collector for heating a heat transfer fluid (HTF); and at least one conduit for transporting the HTF into and out of the at least one solar thermal collector; wherein said at least one conduit is of a foam or plastics material.

A rigid solar thermal panel created from thin flexible materials, including a solar absorber layer of a metal sheet coated with a solar absorbent material having dimples, a tensioned optical film above an upper surface of the solar absorber layer, and an insulation layer. The insulation layer is spaced apart from a lower surface of the solar absorber layer to form a cavity. The dimples project into the cavity and at least one of the dimples is in contact with the insulation layer, thereby providing rigid support for the rigid solar thermal panel.

It is provided a solar energy module for converting solar radiation to thermal energy. The module includes a thermally insulating element transmissive to solar radiation and having low transmissivity to thermal infra-red radiation, an absorbing element, a sealed enclosure, and a variable portion in the envelope of the sealed enclosure. This portion is adapted for varying the volume available to gas enclosed in the enclosure in accordance with changing temperature of the enclosed gas. Also, it is provided a solar energy module which includes a thermally insulating element, an absorbing surface and liquid pipes for absorbing the solar radiation, and an air duct thermally coupled thereof. The heated liquid and the heated air are usable for a variety of thermal applications. A heat storage may be thermally coupled to the absorbing surface and to the liquid pipes. The air duct has several air valves, and is associated with a controller for regulating air flow through the air duct. The controller may regulate heat flow in accordance with an optimization program, receiving inputs from several sources, like a sensor monitoring a building, a sensor monitoring the solar energy module, and an environment sensor.