Patent Application
20100024866
The subject matter disclosed herein relates generally to solar energy concentrators, and, more particularly, to static solar concentrators that harnesses off-angle sunlight using bifacial cells.
Static solar concentrators that operate in low sun concentrations, such as in the range of two suns to five suns, may be used to reduce the total solar cell area in a module (and thus the expense) while still producing a favorable level of power. Other solar concentrators typically use optical structures to focus highly concentrated light onto a solar cell. These optical structures perform well when exposed to direct sunlight but are less effective for off-angle sunlight. Therefore, mechanical tracking systems are used to control the angle of the optical structure with respect to the sun. In such embodiments, much of the cost of a module is associated with the mechanical tracking systems.
It would be desirable to increase optical efficiency without using mechanical tracking systems.
In accordance with one embodiment disclosed herein, a solar energy concentrator system comprises an optically transparent component, a bifacial solar cell situated within the optically transparent component and configured to intercept sunlight, and a reflective component configured to reflect un-intercepted sunlight towards the bifacial solar cell. The bifacial cell is configured to be positioned with a first surface facing sunlight and a second surface facing the reflective component.
In accordance with another embodiment disclosed herein, a solar energy concentrator system comprises an optically transparent component, bifacial solar cells arranged in an array, situated in the optically transparent component, and configured to intercept sunlight, and a reflective component facing the optically transparent component and configured to reflect un-intercepted sunlight towards the bifacial solar cells. The bifacial cells are configured to be positioned with a first surface facing sunlight and a second surface facing the reflective component.
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:
Embodiments disclosed herein include solar energy concentrators. As used herein, singular forms such as “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.
In one embodiment, as shown in
The bifacial solar cell 14 is situated such that a first surface 13 of the bifacial solar cell 14 faces sunlight and a second surface 15 of the bifacial solar cell 14 faces the reflective component 16. The two surfaces of bifacial solar cell may have the same efficiency or different efficiencies. In an embodiment wherein the surfaces have different efficiencies, the bifacial solar cell 14 is situated such that a first surface with higher efficiency faces sunlight and a second surface with relatively lower efficiency faces the reflective component 16.
The reflective component 16 is situated so as to face the bifacial solar cell 14. The surface area of the bifacial solar cell 14 is less than the surface area of the solar energy concentrator system 10. The bifacial solar cell 14 is configured to intercept sunlight passing through the third component. However, only a portion of sunlight 24 is intercepted by the bifacial solar cell 14. The un-intercepted sunlight 26 will head toward the reflective component 16. The reflective component 16 is configured to reflect the un-intercepted sunlight 26 toward the first or second surface of the bifacial solar cell 14.
Not all sunlight reflected by the reflective component 16 can intercept the first or second surface the bifacial solar cell 14. Therefore, the third component 22 is configured to direct sunlight 28 that is reflected by the reflective component 16, and not intercepting the bifacial solar cell, towards the bifacial solar cell 14. The third component 22 and the reflective component 16 are also adapted to direct the sunlight (not shown) reflected from the bifacial solar cell back onto the bifacial solar cell 14. In effect, the reflective component 16 and the third component 22 together form a total internal reflection structure, reflecting sunlight within the system and directing sunlight toward the bifacial solar cell.
In another embodiment, to deal with technical challenges in making a complete total internal reflection structure, the third component 22 and the reflective component 16 can be configured to reflect the sunlight within the system as many times as possible. Therefore, the third component 22 and the reflective component 16 can be adapted to direct at least a part of sunlight reflected from the bifacial solar cell 14 and the reflective component 16 toward the bifacial solar cell 14.
The reflective component 16 may comprise a series of angled surfaces as shown in
The third component 22 may also be configured to provide structural protection to the bifacial solar cell 14, and, in one embodiment, is configured to protect the bifacial solar cell from damage due to external elements. In one embodiment, the third component 22 comprises glass, the second component 20 comprises ethylene vinyl acetate, and the first component 18 comprises molded glass. The reflective component 16 may comprise a metal, for example, silver, coated on the bottom side of the first component 18. In another embodiment, the first component 18 comprises an optically transparent polymer and the reflective component 16 comprises a metal sheet supporting the first component 18. The third component comprising glass is laminated to second component 20, in one embodiment.
The system 10 further comprises a support structure 30 for the reflective component 16. The support structure 30 also provides structural support for the system 10. In one embodiment, the support structure comprises molded polymer. Alternately, the support structure can be integral to the reflective component 16.
In another embodiment 40 shown in
In another embodiment shown in
The bifacial solar cells 14 can be arranged in an array in the optically transparent component to form a larger solar energy concentrator system 60 as shown in
The solar energy concentrator system 10, 40 and 50 may comprise a self-contained module. A plurality of solar energy concentrator systems 10, 40 and 50 can be arranged in an array packaged by clamping them together to form a high-level concentrator system, for example. The solar energy concentrator system 10 may additionally be designed as a planar structure. The planar configuration enables the solar energy concentrator system 10, 40 and 50 to be used anywhere a standard flat plate solar module is used. In one embodiment, the solar energy concentrator system 10, 40 and 50 can be used as built-in facades or other building integrated applications.
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.
