Patent Application
20060107993
The invention relates generally to building elements such as roof tiles, window panes, and building facades and more specifically to building elements having solar energy converters included therein.
Solar energy converters, such as photovoltaic or thermal converters, typically have high material cost, high installation cost and thus a high cost of energy (cost per kWh). One approach to reduce the material cost is to concentrate solar irradiation (focus light) onto an energy converter by means complex optical surface structuring, such as by a Fresnel lens. Such approaches are difficult to implement and have had difficulty in penetrating the renewable energy market.
Briefly, in accordance with one embodiment of the present invention, a building element comprises a fluorescence collector comprising a substrate and particles dispersed in the substrate to absorb light from a plurality of directions and radiate the absorbed light. The fluorescence collector has opposing surfaces and a connecting surface between the opposing surfaces. The combination of the substrate and the particles is sufficiently transparent to permit light to reach the particles for absorption and to permit particles to radiate. At least two different portions of the fluorescence collector have different absorption spectrums. The building element further comprises a solar energy converter configured for receiving radiated light from the fluorescence collector of the building element.
In accordance with another embodiment of the present invention, a roof tile comprises a fluorescence collector comprising a substrate and particles dispersed therein to absorb light from a plurality of directions and radiate the absorbed light. The fluorescence collector has opposing surfaces and a connecting surface between the opposing surfaces, and the particles comprise a dye, quantum dots, or combinations thereof. The roof tile further comprises a solar energy converter configured for receiving radiated light from the fluorescence collector of the roof tile.
In accordance with another embodiment of the present invention, a window pane comprises a fluorescence collector comprising a substrate and particles dispersed therein to absorb light from a plurality of directions and radiate the absorbed light. The fluorescence collector has opposing surfaces and at least one connecting surface between the opposing surfaces, and the particles comprise a dye, quantum dots, or combinations thereof. The window pain further comprises a solar energy converter configured for receiving radiated light from the fluorescence collector of the window pane.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
In one embodiment of the present invention, a building element 14 (
Substrate 10 may comprise any shape (geometric volume) and any material which can be formed without destroying the selected particles 30. In one example, substrate 10 comprises a plastic. In a more specific example, substrate 10 comprises a polycarbonate such as LEXAN® polycarbonate available from the General Electric Company. Other potential materials include materials such as low fabrication temperature glasses and ceramics, for example. Other non-limiting examples include polymethylmethacrylate and polystyrol as well as combinations of any of the aforementioned examples. As described in more details below, the substrate materials, the particle materials, or combinations of substrate and particle materials can be optimized to contribute to a preselected light absorption characteristic, appearance of color, shadowing, or combinations thereof. Example embodiments of different portions of the fluorescence collector having different absorption spectrums are also provided below.
Typically substrate 10 includes a plurality of connecting surfaces (such as edges 24, 124, 224, 424), but the present invention is also applicable to round or curved perimeter substrates with one continuous connecting surface. When mirrored surfaces are included on connecting or opposing surfaces, such mirrored surfaces are typically formed by applying a silver coating that is strong enough to withstand rain and other environmental factors. However, “mirrored surface” is intended to encompass any surface with properties that enable reflection. Efficiency is improved in embodiments wherein bottom opposing surface 20 comprises a mirrored surface 28 (
As stated above, solar energy converter 32 is mounted at an unmirrored portion of the fluorescence collector of the building element. Typically the converter will be mounted on the unmirrored connecting surface 424 itself, but not necessarily as can be seen by
The embodiments of
In fluorescence collector 14, particles 30 absorb sun light (radiation energy) from a plurality of directions and emit the absorbed light with a defined spatial characteristic (such as, for example spherical or cone-shaped). Due to emission in various or all directions and the effect of total reflection on the collector surfaces, light is concentrated towards the connecting surfaces of the substrate. This effect is known as light pipe/edge glow effect. For example, in a four connecting surface embodiment with three of the surfaces comprising mirrored surfaces, about 15-60% of the total radiation power will reach the fourth connecting surface covered with one or more converters. For a photovoltaic (PV) cell as converter, the proposed module converts about one quarter of the irradiated power, and such cells require only a small fraction of the irradiated surface area (about 1/30). The net effect is a concentration of the light to multiples of the natural irradiation. Thus, the PV cell area needed per Watt produced power is reduced according to the “number of suns” leading to a substantial reduction of material cost and hence results in a corresponding reduction of total system cost with estimated savings of Cost of Energy of about 20-40%.
As stated above, in one embodiment the substrate contributes to a preselected light absorption characteristic of the building element, a preselected appearance of color of the building element, or combinations thereof. In an additional or alternative aspect to this embodiment, substrate 110 comprises a plurality of layers 110, 210, 310 with at least one of the layers having a different absorption spectrum than at least one other of the layers. A benefit to this aspect is that the layers may be optimized separately as to cover the absorption and emission in different wavelength intervals of the solar spectrum.
In a more specific embodiment, to provide (either alone or in combination with the multiple layer embodiment) the different absorption spectrums, the particles in substrate 210 comprise at least two types of different particles 130 and 230 with at least one type of particle having a different absorption spectrum than at least one other type of particle. In another more specific aspect, the fluorescence collector 16 has one type of fluorescence particle with a wide absorption spectrum (such as more than one hundred nanometers, for example).
In an additional or alternative aspect, the particles contribute to a preselected appearance of color of the building element, a preselected light absorption characteristic of the building element, a preselected shadowing characteristic, or combinations thereof. When the particles comprise dyes, typically fluorescent dyes themselves create the effects, but additional dye or other material can be added if desired.
In the embodiments of
Additionally, although
In a specific roof tile embodiment, which is not limited to the embodiment of
Thus, embodiments of the present invention can provider a roof tile element, which is tile like in shape and appearance and can thus be used to provide a normal roof tile appearance. In an even more specific embodiment, a certain number of these roof elements will replace parts of a roof and produce electrical energy without compromising the optical appearance of a tile-structured roof.
In a specific window pane embodiment, a window pane comprises a fluorescence collector 16 comprising substrate 10 and particles 30 dispersed therein to absorb light 12 from a plurality of directions and radiate the absorbed light, the fluorescence collector having two opposing surfaces 18 and 20 and a connecting surface between the opposing surfaces. Typically a mirrored surface 26 is present on at least one portion of the connecting surface, and a solar energy converter 32 (meaning at least one) mounted at an unmirrored portion (meaning at least one) of the fluorescence collector of the window pane. Each of the examples and embodiments descried above with respect to building elements generally is likewise applicable to the window pain embodiment with selective shadowing being particularly beneficial.
With regard to the building facade embodiments, such embodiments can be similar to aluminum, vinyl, or wood siding type embodiments. One example is an overhanging siding element which would resemble the building elements of
The previously described embodiments of the present invention have many advantages, including the advantage of providing a building element with integrated fluorescence-based light collection in order to conduct the radiation energy to the solar energy converter for electricity or heat production such that mounting of photovoltaic (PV) or thermal collectors on top of the existing building elements is no longer needed.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
