A solar collector has an opaque cover heated by solar energy. Heat flows from the opaque cover by conduction, convection, and infrared emittance across a gap within an at least substantially airtight enclosure to an absorber containing a working fluid. The exterior surface of the opaque cover has high solar energy absorptance and the interior surface has high infrared emittance. The exterior surface preferably has low infrared emittance. In one embodiment, fully wetted surface geometry permits direct and reflected infrared absorption by the absorber. The opaque cover eliminates the weight, cost and other shortcomings of glass. A hollow continuous side wall with rounded corners provides an embodiment that is robust yet economical, that is easy to manufacture and seal, that permits a reduced thickness of the opaque cover and mitigates the destructive potential of severe winds, and that can withstand the compressive forces experienced by an evacuated solar collector.

A spectrally selective solar absorber is described and comprises a substrate, double cermet layers comprising multi-metal nanoparticles embedded in a dielectrics matrix, and double antireflection layers deposited on cermet layers. The tungsten or titanium or tantalum infrared reflector layer suppressing the diffusion of substrate elements and multi-metal nanoparticles in the cermet are disclosed.

A cyclical salinity-gradient power generating system based on phase change materials and solar photothermal conversion is provided. The system comprises a solution supplying device, a power generating device and a power output device. The solution supplying device provides seawater with high and low concentration as salinity-gradient energy source of the power generating device; the power generating device implements day-and-night cyclical salinity-gradient power generation; the power output device stores electricity, part of which is used as providing power for the pumps inside the system and part of which is used as system output. A cyclical salinity-gradient power generating method based on phase change materials and solar photothermal conversion is also provided.

Systems and methods for radiative cooling and heating are provided. For example, systems for radiative cooling can include a top layer including one or more polymers, where the top layer has high emissivity in at least a portion of the thermal spectrum and an electromagnetic extinction coefficient of approximately zero, absorptivity of approximately zero, and high transmittance in at least a portion of the solar spectrum, and further include a reflective layer including one or more metals, where the reflective layer has high reflectivity in at least a portion of the solar spectrum.

Systems and methods for radiative cooling and heating are provided. For example, systems for radiative cooling can include a top layer including one or more polymers, where the top layer has high emissivity in at least a portion of the thermal spectrum and an electromagnetic extinction coefficient of approximately zero, absorptivity of approximately zero, and high transmittance in at least a portion of the solar spectrum, and further include a reflective layer including one or more metals, where the reflective layer has high reflectivity in at least a portion of the solar spectrum.

A method is disclosed for producing a plasmonic-nanostructure spectrally selective solar absorber having high solar absorptance, low thermal emittance, and superior thermal stability. The method includes the steps of providing an alloy structure containing a base metal and a copper alloying impurity, wherein copper has a weight percent concentration in the alloy of at least 0.25%; and applying an alkaline solution to a surface of the alloy structure to selectively dissolve base metal elements at the surface resulting in fabrication of sponge-like copper nanostructures on the surface configured to scatter, trap, and absorb light in solar wavelengths.

A method is disclosed for producing a plasmonic-nanostructure spectrally selective solar absorber having high solar absorptance, low thermal emittance, and superior thermal stability. The method includes the steps of providing an alloy structure containing a base metal and a copper alloying impurity, wherein copper has a weight percent concentration in the alloy of at least 0.25%; and applying an alkaline solution to a surface of the alloy structure to selectively dissolve base metal elements at the surface resulting in fabrication of sponge-like copper nanostructures on the surface configured to scatter, trap, and absorb light in solar wavelengths.

The present invention describes an improved multilayer solar selective coating useful for solar thermal power generation. Solar selective coating of present invention essentially consists of Ti/Chrome interlayer, two absorber layers (AlTiN and AlTiON) an anti-reflection layer (AlTiO). Coating deposition process uses Ti and Al as the source materials, which are abundantly available and easy to manufacture as sputtering targets for industrial applications. The present invention allows deposition of all the layers in a single sputtering chamber on flat and tubular substrates with high absorptance and low emittance, thus making the process simpler and cost effective. The process of the present invention can be up-scaled easily for deposition on longer tubes with good uniformity and reproducibility. The coating of the present invention also displays improved adhesion, UV stability, corrosion resistance and stability under extreme environments.

A compact, three-dimensional (3D) photovoltaic charging system comprising a photovoltaic unit encased in a transparent housing, a power management unit, and a support base. The photovoltaic unit having non-coplanar photovoltaic surfaces that are positioned at a relative distance and a relative orientation. Compared to conventional flat solar panels, the 3D photovoltaic charging system can collect light vertically, therefore amplifying solar module power density, defined as power output per installation footprint area. A photo-tracking, 3D photovoltaic charging system is also described, having a photovoltaic unit encased in a transparent housing, a power management unit, and means to track a source of electromagnetic radiation. The photo-tracking, 3D photovoltaic charging system tracks a moving light source, resulting in improved light flux intake, and therefore, enhanced electric power output.

A process for the production of an optically selective coating of a receiver substrate of a suitable material for solar receiver devices particularly suitable for operating at high temperatures, more specifically for receiver tubes of linear parabolic trough, which comprises: deposition of a layer reflecting infrared radiation consisting of a high-melting metal on a heated receiver substrate of a suitable material; annealing under the same temperature and pressure conditions as the deposition of the reflecting layer; deposition on the high-melting metal of one or more layers of metal-ceramic composite materials (CERMET), wherein the metal is W and the ceramic matrix is YPSZ (“Yttria-Partially Stabilized Zirconia”); deposition on the cermet of an antireflection layer; annealing under the same temperature and pressure conditions as the depositions of the cermet and antireflection layers.