DOUBLE-WALLED SOLAR HEATER APPARATUS AND METHOD FOR USE

Abstract

The solar heater apparatus disclosed comprises an inner container and an outer container each having an opening forming a mouth. The inner container is contained within the outer container and has on its outside surface a solar-selective coating optimized to absorb a large fraction of the incident solar radiation while reradiating little of the absorbed energy. The two containers are joined creating one unified apparatus with a reservoir, an opening and a void between the two containers. The void is evacuated to reduce the heat loss due to thermal conduction from the inner container and the contents of the reservoir. In operation, the reservoir is filled with material and exposed to the sun. The solar radiation from the sun penetrates the outer container and is absorbed by the solar-selective coating and, by conduction, passes thermal energy through the inner container into the apparatus reservoir heating the reservoir contents.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 60/845,697 filed on Sep. 19, 2006 and all of said application is herein incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT:

Not Applicable.

NAMES OF PARTIES TO JOINT RESEARCH AGREEMENT

Not applicable.

REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX

Not Applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to techniques for heating materials using a solar heat apparatus. In one embodiment, the invention relates a solar heat apparatus for heating liquids, such as water, for disinfecting and cooking purposes.

2. Description of the Prior Art

The need for safe drinking water covers the entire world's population. Non-portable drinking water is a major problem for much of the world's population.

Chlorine is considered a well known technique for disinfecting drinking water. However, chlorine is a toxin that must constantly be replenished in order to be effective. As a replenishable chemical, there is always a continuing cost incurred. And certain logistical situations make delivery of such chemicals difficult.

The lack of fuel for cooking is a very serious problem in many parts of the developing world. Large numbers of people are forced to walk many hours every day to gather sufficient firewood to cook their daily meal.

Other techniques of disinfection such as membranes, resin beds, and the like, require electricity for operation. This source of energy may not be available at the site or would be expensive when compared to other methods.

Heat is a very effective method of disinfecting drinking water. However, the lack of fuel in certain locations can limit the application of fuel based heating methods to disinfect water or heat water for cooking.

Contrary to popular opinion, boiling water for many minutes or even hours is not necessary to successfully disinfect. Numerous investigations have been conducted to demonstrate that temperatures much lower than the sea level boiling point (100 C) can successfully disinfect drinking water. Heat inactivation of microorganisms is exponential with time. In general, disinfection times can range from instantaneous at 90 C to 20 minutes at 55 C.

Applying solar energy to heat liquids is known in the prior art. But many implementations, such as flat-plate collectors or parabolic trough systems, are inefficient. Some evacuated-tube collectors can achieve high temperatures (170° F. to 350° F.), temperatures high enough to disinfect water. However, many of these evacuated-tube collectors are more expensive than other implementations, with glass-to-metal seals and unit area costs about twice that of flat-plate collectors.

All-glass evacuated-tube designs are now available which address some of the efficiency issues with prior designs. These “dewar” design tubes feature a vacuum contained between two concentric glass tubes, with the solar-selective coating on the outside surface of the inside tube. There are no glass-to-metal seals in this implementation. This type of evacuated tube has the potential to become cost-competitive with prior solar collector designs.

In conjunction with the physical structure of new solar collectors, the solar-selective coating provides improvements to the prior art. An ideal solar-selective coating is a very efficient absorber of light of the wavelengths of the solar radiation spectrum, while simultaneously being a very poor radiator of wavelengths in the spectral range of bodies at temperatures of 100-300 deg. C. Solar coating development now includes double cermet layer structure for solar-selective coatings which have a very high photo-thermal conversion efficiency. And recent research achievements have allowed the double cermet solar-selective coatings to be economically manufactured. Other solar selective coatings which are applicable to this invention include but are not limited to black nickel, black chrome, and other nanostructured materials.

These advances in solar collector design and solar coatings are creating opportunities for improved implementations of solar-powered heating. Applications related to water heating for houses, industrial facilities, pools and similar applications are incorporating these improvements. However, small, personally portable methods to harness solar power for heating materials, cooking and disinfecting water are not readily available.

Thus, the need exists for an economical and portable technique for heating materials with solar energy for purposes such as cooking or disinfecting drinking water.

BRIEF SUMMARY OF THE INVENTION

To address the shortcoming of the prior art, this invention combines the technology advancements used for solar heating and applies them to a new apparatus to heat materials such as water in a portable and economically efficient manner.

Advances in solar collector design and manufacture enable more efficient solar collector designs. Advances in solar coatings now include cermet solar-selective coatings which have a very high photo-thermal conversion efficiency and very low energy losses due to reradiation. Advances in manufacturing allow these coatings to be applied in an economical way. The costs of high-temperature solar collectors manufactured by these new manufacturing methods make collectors using cermet layers much more economically appealing than other solar collectors.

The new apparatus disclosed, a solar heater apparatus, comprises an inner container and an outer container each having an opening forming a mouth. The inner container is smaller than and contained within the outer container. The two containers are joined at the mouth of each creating one unified container with an internal reservoir, an opening and a void between the two containers. The gas in the void is removed to create a vacuum that helps reduce thermal conductance loss.

Although similar, this design deviates from past dewar flask implementations. The outer container of the apparatus is transparent allowing solar radiation to be passed through the void and on to the inner container. The outside surface of the inner container is coated with a solar-selective coating which absorbs solar radiation and converts that radiation to thermal energy. The thermal energy is passed by conduction through the inner container and to the contents of the inner container. In one implementation, using a double cermet layer structure as the inner container coating enables the inner container to efficiently achieve temperatures sufficient to disenfect or sterilize water in the apparatus.

This apparatus design provides a portable apparatus wherein non-sterile water can be put into the apparatus, the apparatus can be set into the sun and solar radiation can heat the water to a temperature sufficient to disinfect or sterilize the water in the apparatus.

It is an object of this invention to provide a solar heater apparatus for heating a material comprising an outer container transparent to solar radiation with a mouth, an inner container with a mouth and an outer surface having a solar selective coating, the inner container is contained within the outer container and both containers are joined at their mouths creating an apparatus opening, an apparatus reservoir, and a void between said outer and inner container.

It is another object of this invention to provide a solar heater apparatus as described above wherein the solar selective coating comprises a coating capable of simultaneously converting to heat at least about 85% of said solar radiation while reradiating less than 15% of the heat while the reservoir temperature is at a temperature of less than 100° C.

It is a further object of this invention to provide a solar heater apparatus as described above wherein the solar selective coating comprises at least one cermet layer.

It is another object of this invention to provide a solar heater apparatus as described above wherein the outer container and the inner container form a self-supporting apparatus whereby the apparatus can be placed on a surface and exposed to solar radiation to transfer heat to the apparatus reservoir.

It is an object of the invention is to provide a method of heating material comprising the steps of providing a solar heater apparatus comprising: an outer container, transparent to solar radiation, having a mouth; an inner container having a mouth and an outer surface having a solar collective coating to absorb solar radiation; the inner container contained within the outer container and both containers joined at their mouths creating an apparatus opening, a apparatus reservoir, and a void between said outer and inner container; and inserting a material into said apparatus reservoir, subjecting said apparatus to solar radiation heating said material and removing said material from said apparatus reservoir.

Another objective of the present invention is to provide a non-chemical apparatus and method for heating materials such as water.

Another object of this invention is to provide a non-toxic apparatus and method for heating materials such as water.

Another object of this invention is to provide a simple apparatus and method for heating materials such as water.

Another object of this invention is to provide an efficient apparatus and method for heating materials such as water.

Another object of this invention is to provide a reliable apparatus and method for heating materials such as water.

Yet another object of this invention is to provide an easy-to-operate apparatus and method for heating materials such as water.

Yet another object of this invention is to provide a self-contained apparatus and method for heating materials such as water.

Yet another object of this invention is to provide an apparatus and method requiring no fossil fuels or electricity for heating materials such as water.

Yet another object of this invention is to provide a portable apparatus and method for heating materials such as water.

These together with other objects of the invention, along with the various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated embodiments of the invention. The foregoing has outlined some of the more pertinent objects of this invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the present invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or by modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1A shows a perspective view of one embodiment of the solar heater apparatus.

FIG. 1B shows a top view of one embodiment of the solar heater apparatus marked for cross-section A-A.

FIG. 2 shows a cross-sectional side view of the embodiment of the invention along section A-A of FIG. 1B.

FIG. 3 shows cross-sectional side view of an alternative embodiment of the invention.

FIG. 4 shows a partial cross-sectional view, defined between section B-B and C-C of FIG. 2 of the solar heater apparatus.

FIG. 5 shows a cross-sectional side view of one embodiment of the solar heater apparatus interacting with solar radiation.

FIG. 6 shows one embodiment of the method of heating material with the solar heater apparatus.

DETAILED DESCRIPTION OF THE INVENTION

Before explaining the disclosed embodiment of the present invention in detail it is to be understood that the invention is not limited in its application to the details of the particular arrangement shown since the invention is capable of other embodiments. Also, the terminology used herein is for the purpose of description and not of limitation.

The Solar Heater Apparatus:

FIG. 1 shows a perspective view of one embodiment of the solar heater apparatus 10. The general shape of this solar heater apparatus embodiment is a spherical flask. This apparatus has an apparatus opening 33 and a base 12 to help serve as a self-supporting structure to stabilize the apparatus when it is resting on a surface.

FIG. 1B shows a top view of the solar heater apparatus 10 marked for cross-section A-A that is used in FIG. 2 and FIG. 4.

FIG. 2 shows a cross-sectional view of the solar collector apparatus 10 comprising a flask shaped inner container 21 and a similarly flask shaped outer container 11 each having an opening forming a mouth, 25 and 13 respectively. The inner container 21 is smaller than and contained within the outer container 11. The two containers are joined (at their respective mouths) creating an apparatus opening 33 and a void 30 between the two containers. The apparatus opening 33 provides access to an apparatus reservoir 34. The air in the void is removed to create a vacuum. This vacuum helps reduce the conductive and convective heat loss. The flask shape of the apparatus helps make it a self-supporting device as well as increase the portability and durability of the apparatus over conventional solar vacuum tubes.

The inner container 21 is coated on its outside surface 22 with a solar-selective coating 24 which absorbs solar radiation and converts that radiation to thermal energy. The thermal energy is transferred by conduction to the inner surface 23 of the inner container 21, heating the contents of the apparatus reservoir 34. Solar radiation comprises radiation from the sun.

One embodiment of the apparatus comprises both containers being made of glass transparent to solar radiation. Examples of suitable glass materials for the containers include, but are not limited to borosilicate glass, offered for sale by Corning Incorporated of Corning N.Y. under the Pyrex trade name as well as glass offered for sale by other companies under other trade names. In this embodiment, the inner and outer containers are joined by standard glassworking methods and the vacuum is created by standard glassworking and vacuum processing methods.

Another embodiment of the apparatus 10 includes the inner and outer containers being made of other materials that are able to maintain a vacuum, withstand high temperatures and provide a sufficient method to connect both containers at their mouths. The outer container 11 can be made from other transparent materials such as but not limited to plastics or transparent crystalline materials. The outer container 11 can also be made from of a combination of transparent material and non-transparent material as long as there is sufficient transparent material to allow solar radiation to pass to the inner container 21. Other embodiments of the invention include the inner container 21 being made from transparent or non-transparent materials such as, but not limited to metal with a solar-selective coating, which construction would make the apparatus 10 more rugged.

Another embodiment of the apparatus 10 includes the use of methods to join the inner and outer containers at their mouths through adhesive or sealing materials such as, but not limited to solder or epoxy that can withstand high temperatures and maintain a vacuum.

FIG. 4 shows a partial cross-sectional view of the inner container 21 of the solar collection apparatus 10 shown in FIG. 2 between sections B-B and C-C. The outside surface 22 of the inner container 21 is coated with a solar-selective coating 24 which absorbs solar radiation and converts that radiation to thermal energy. The embodiment of the apparatus 10 shown in FIG. 4 shows a double cermet layer structure as the inner container solar-selective coating 24. This coating helps the inner container 21 achieve sufficient temperatures to heat materials in the apparatus 10 for particular purposes, such as the temperature sufficient to disinfect or sterilize water. In this embodiment, the double cermet solar-selective coating 24 is made of multiple layers of material. A first layer against the outside surface 22 of the inner container 21 is a metal infrared-reflecting layer 25; a second layer is an absorbing layer composed of two homogeneous cermet sub-layers, the first sub-layer 26 near the metal infrared layer has a high metal volume fraction (HMVF) and the second sub-layer 27 has low metal volume fraction (LMVF); and a third anti-reflection layer 28 is composed of a transparent dielectric material.

In double or other cermet layer solar-selective coatings 24, radiation of wavelengths typical of solar radiation is absorbed by the coating which has very low reflectivity in this range of wavelengths, while radiation of wavelengths typical of materials at a temperature in the range of 100-300 degrees C. is not radiated due to the coating's very high reflectivity in this range of wavelengths. Radiation of converted heat from the solar selective coating is also defined as reradiating.

Advances in manufacturing allow these coatings to be applied in an economical way. As an example, and not as a limitation, one method of manufacture includes a two-target dc magnetron sputtering technology enables metal-aluminum nitride (M-AlN) and metal-aluminum oxide (M-Al₂O₃) solar-selective coatings to be economically applied to solar collectors.

Embodiments of solar selective coatings include, but are not limited to those capable of near simultaneously converting to heat at least about 85% of said solar radiation while reradiating less than 15% of said heat while said coating temperature is at a temperature of less than 100° C. These conversion and reradiation values become less efficient as the temperature of the apparatus and the coating increases. Examples of some specific solar selective coatings include, but are not limited to black nickel, black chrome, dark paint, other nanostructured materials and those embodiments described by U.S. Pat. No. 5,523,132 and U.S. Pat. No. 6,632,542 both of which are incorporated by reference.

Although FIG. 1 and FIG. 2 illustrate a spherical shape, other shaped containers are anticipated. For example, another embodiment of the apparatus is shown in FIG. 3. In this embodiment, the inner and outer containers are of the form of cylindrical, straight-sided vessels forming a shape similar to a pot or cup. The apparatus comprises the outer container 11, and inner container 21 with the solar-selective coating 24 applied to the outer surface 22 of the inner container 21. Although not required in other embodiments, in this embodiment, a hollow transparent plug 40 is provided and shaped to be removably fitted into the apparatus opening. The plug can be made from material similar to the container of the apparatus. The void 41 within the hollow plug can be evacuated and a solar-selective coating 44 can be applied to the inside surface 42 of the bottom portion of the plug 40. The solar-selective coating 44 performs the same purpose and therefore can be selected from the same type of coating as is suitable for the inner container 21 coating. Although not required, to seal the plug 40 into the apparatus opening, an elastic retaining ring 45 can be mounted on the plug to create a seal between the plug and the apparatus. A handle 43 can be incorporated into the plug 40 to provide a means to remove the plug from the apparatus and allow access to the apparatus reservoir 34.

Another embodiment of the invention includes adding support elements in the void between the inner and outer containers to support the inner container and make the assembly more portable and durable.

Another embodiment of the invention includes adding a rigid support for the apparatus which supports the apparatus over or near an appropriately shaped reflective surface to increase the intensity of the sunlight that strikes the apparatus.

Another embodiment of the apparatus includes mounting the apparatus in proximity to a solar reflective surface so that sunlight and solar radiation which strikes the reflective surface is reflected onto the apparatus, thereby increasing the incident solar radiation and therefore the energy absorbed by the apparatus in a given time.

Self-supporting shapes are convenient for some embodiments of the apparatus because they allow the apparatus to be more self-contained allowing it to be placed in solar radiation without the need for additional equipment. However, it is anticipated that containers and holders may also be provided that can assist in positioning the apparatus to continue to be subjected to solar radiation while also holding the contents of the material in the apparatus reservoir.

Another embodiment of the apparatus includes adding material to the outer container to make the apparatus self-supporting or help protect the apparatus from breakage when being used or moved. Rigid frames, or caging can be used to encase the outer container yet still allow enough transparent area for solar radiation to interact with the inner container. An embodiment may also include a rigid baseplate to protect the base of the outer container.

Solar Heater Apparatus in Operation:

The following operational description uses the solar heater embodiment as shown in FIG. 1 and FIG. 2 for illustration purposes and not for limitation.

FIG. 6 illustrates one method of using the solar heater apparatus 10. As shown in FIG. 6, the method starts with step 600 and is followed by Step 610 of providing a solar heater apparatus 10 comprising an outer container 11 transparent to solar radiation having a mouth 13, an inner container 21 having a mouth 25 and an outer surface 22 having a solar selective coating 24 and the inner container 21 is contained within the outer container 11. Both containers are joined at their mouths creating an apparatus opening 33, an apparatus reservoir 34, and a void 30 between said outer and inner container.

Step 620 comprises inserting a material 35 such as water into the apparatus reservoir 34. The material 35 is put in and held within, or otherwise retained in the apparatus reservoir 34.

Other materials 35 that can be inserted into the apparatus reservoir 34 include, but are not limited to waxes, plastics, surgical devices, cooking utensils, edible items, food and other materials that can be affected by heat.

Step 630 comprises exposing the solar heater apparatus 10 to solar radiation. As illustrated in FIG. 5, in this step, the incident solar radiation 50, defined as that solar radiation that falls on or strikes the apparatus 10, is absorbed by the solar-selective coating 24 and converted to and passed by conduction as heat through the inner container 21 into the apparatus reservoir 34, thereby raising the temperature of the content of the apparatus 10. In this embodiment, the apparatus 10 is exposed to the sun. The solar radiation from the sun penetrates both the outer container 11 and the void 30 between the outer and the inner container. The solar radiation is absorbed by the solar-selective coating 24 and converted to and passed through the inner container 21 into the apparatus reservoir 34 heating the water. The vacuum created in void 30 reduces the conductive and convective heat loss from the inner container 21 and the content of the apparatus reservoir 34. As described earlier, the solar-selective coating 24 reduces the reradiation, or radiation of converted heat, from the inner container 21. Although not required, an insulating plug 36 reduces heat loss from the apparatus reservoir 34 due to convection, conduction and evaporation from the contents of the apparatus 10. Thus, the apparatus 10 allows the water temperature to heat, or rise relative to the surrounding ambient temperature, for a sufficient period of time, to disinfect or sterilize the water or heat it for other purposes such as cooking. Temperatures sufficient to disinfect water include temperatures of about 50° C. and above.

Step 640 comprises removing the material 35 from the solar heater apparatus reservoir 34 for use.

The method is finished with Step 650.

Although this apparatus is not limited to functioning with water, the use of the apparatus to disinfect water is illustrative of the efficiencies achieved with this solar heater apparatus. The temperature sufficient for the disinfecting of water is a function of the water temperature in the apparatus reservoir. The temperature of the apparatus reservoir is related to the solar radiation the apparatus is exposed to, the time of the exposure and the efficiency of the apparatus in absorbing and retaining that radiation. Analysis of one embodiment of this apparatus shows that it is possible to achieve sufficient temperatures to disinfect water more efficiently than other devices in the art. Efficient embodiments such as this are helpful for situations with low levels of solar radiation or situations where speed of disinfection is important.

While methods have been described as being used for sterilizing water, other embodiments of this method have other useful applications such as heating liquids, food or any other materials that can be put into the apparatus reservoir 34 for various purposes, including but not limited to cooking, medical applications, process heat or other uses.

While the apparatus and methods have been described, disclosed, illustrated and shown in various terms of certain embodiments or modifications which it has presumed in practice, the scope of the invention is not intended to be, nor should it be deemed to be, limited thereby and such other modifications or embodiments as may be suggested by the teachings herein are particularly reserved especially as they fall within the breadth and scope of the claims here appended.

With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention.

Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. Although this invention has been described in the above forms with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and numerous changes in the details of construction and combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention.

Claims

1. A solar heater apparatus for heating material comprising:

an outer container, transparent to solar radiation, having a mouth;

an inner container having a mouth and an outer surface having a solar selective coating to absorb solar radiation; and

said inner container contained within said outer container and both containers joined at their mouths creating an apparatus opening, an apparatus reservoir, and a void between said outer and inner container.

2. The apparatus in claim 1 wherein said solar selective coating comprises a coating capable of near simultaneously converting to heat at least about 85% of said solar radiation while reradiating less than about 15% of said heat while said coating is at a temperature of less than about 100° C.

3. The apparatus in claim 1 wherein said solar selective coating comprises at least one cermet layer.

4. The apparatus in claim 1 wherein said outer container and said inner container form a self-supporting apparatus whereby said apparatus can be placed on a surface and exposed to solar radiation to transfer heat to said apparatus reservoir.

5. The apparatus in claim 1 wherein said outer container and said inner container are flask shaped whereby said apparatus can be placed on a surface and exposed to solar radiation to transfer heat to said apparatus reservoir.

6. The apparatus in claim 1 further comprising:

a plug shaped to fit in said apparatus opening;

said plus comprising a transparent hollow evacuated cylinder having a bottom portion, an inside surface and a solar selective coating on said inside surface of said bottom portion; and

said outer container and said inner container are pot shaped whereby said apparatus can be placed on a surface and exposed to solar radiation to transfer heat to said apparatus reservoir.

7. The apparatus in claim 4 wherein said apparatus is capable of near simultaneously converting to heat at least about 85% of said solar radiation while reradiating less than about 15% of said heat while said coating is at a temperature of less than about 100° C.

8. The apparatus in claim 4 wherein said solar selective coating comprises at least one cermet layer.

9. The apparatus in claim 4 wherein said reservoir is capable of holding water and said solar selective coating comprises at least one cermet layer capable of transferring heat to raise the temperature of said water to a temperature at or above a temperature sufficient to disinfect water.

10. The apparatus in claim 4 wherein said reservoir is capable of holding a material and said solar selective coating comprises at least one cermet layer capable of transferring heat to raise the temperature of said material to a temperature above an ambient temperature.

11. The apparatus in claim 4 wherein said reservoir is capable of holding an edible material and said solar selective coating comprises at least one cermet layer capable of transferring heat to raise the temperature of said edible material.

12. The apparatus in claim 4 further comprising a solar reflective surface wherein said inner container is placed in proximity to said reflective surface whereby said solar radiation incident to said apparatus is increased.

13. A method of heating material comprising the steps of:

providing a solar heater apparatus comprising: an outer container, transparent to solar radiation, having a mouth; an inner container having a mouth and an outer surface having a solar collective coating to absorb solar radiation; said inner container contained within said outer container and both containers joined at their mouths creating an apparatus opening, a apparatus reservoir, and a void between said outer and inner container; and

inserting a material into said apparatus reservoir;

exposing said apparatus to solar radiation heating said material; and

removing said material from said apparatus reservoir.

14. The method of claim 13 wherein said solar selective coating comprises a coating capable of near simultaneously converting to heat at least about 85% of said solar radiation while reradiating less than about 15% of said heat while said coating is at a temperature of less than about 100° C.

15. The method of claim 13 wherein said solar selective coating comprises at least one cermet layer.

16. The method of claim 13 wherein said apparatus is self-supporting.

17. The method of claim 16 wherein said apparatus is capable of near simultaneously converting to heat at least about 85% of said solar radiation while reradiating less than about 15% of said heat while said coating is at a temperature of less than about 100° C.

18. The method of claim 16 wherein said solar selective coating comprises at least one cermet layer.

19. The method of claim 17 wherein said material comprises water and said solar radiation raises the temperature of said water to a temperature at or above a temperature sufficient to disinfect water.

20. The method of claim 17 wherein said solar radiation raises the temperature of said material to a temperature above an ambient temperature.