Patent Application
20090320901
The present invention relates to a photovoltaic cell, and more specifically, to a concentration photovoltaic (CPV) cell system with light guide.
A photovoltaic cell employs the photovoltaic effect to convert solar light energy into electric energy and thereby achieving the purpose and benefits of power generation. According to the currently available techniques, the photovoltaic cell is directly exposed to sunlight for receiving and converting the solar energy into electric energy.
Generally speaking, a photovoltaic cell system must require a large amount of expensive photovoltaic material. Up to date, there is not an efficient method for utilizing photovoltaic cells to convert solar energy into electric energy. Therefore, the current unit cost (dollar per watt) of solar power generation is very expensive. To reduce the manufacturing cost of photovoltaic cell modules, external mechanisms and optical elements have been developed to reduce the usage of photovoltaic cells.
Concentration photovoltaic (CPV) cells have been used to achieve the purpose of concentrating solar energy and reducing the required amount of the expensive photovoltaic cells. The purpose is to focus the sunlight of the largest possible surface area onto the same focal point to increase the geometric concentration ratio (GCR), which translates into the reduction of the amount of photovoltaic cells required. However to ensure the proper focusing of sunlight onto the chip, a tracker is required to constantly orient the cells toward the sunlight, which also occupies additional space and is relatively heavy. When the tracker is not accurately oriented toward the sunlight, the solar energy efficiency of the CPV system is drastically reduced.
A primary object of the present invention is to provide a concentration photovoltaic cell system with light guide, in which a solar energy converter is not directly exposed to sunlight to avoid the reduced energy conversion efficiency caused by temperature rising at photovoltaic cell chips thereof.
Another object of the present invention is to provide a concentration photovoltaic cell system with light guide that has the increased GCR and light concentrating efficiency to reduce the required amount of expensive photovoltaic cells.
To achieve the above and other objects, the concentration photovoltaic cell system with light guide according to the present invention consists of a concentrator for focusing sunlight; a light guide arranged at the focal point of the concentrator, so that the focused light is fully coupled to the input end of the light guide and propagates to the output end of the light guide; and a solar energy converter arranged at the output end of the light guide for receiving and converting the light projected from the light guide into electric energy. In the present invention, the solar energy converter is a photovoltaic cell.
In the present invention, the concentrator is a light focusing lens, a reflective mirror, a thin-film concentrator, or any other optical element with equivalent light concentrating functionality.
In the present invention, the light guide consists of a light guiding medium and a lens assembly. The focused sunlight propagates through the light guiding medium to the lens assembly, and is reflected by the lens assembly onto the solar energy converter and converted into electric energy.
The light guide may further include a light splitter located at a center of the lens assembly. The light guiding medium has its output end aligned with the light splitter. When the focused light is transferred via the light guiding medium to the light splitter, the light projected onto the light splitter is reflected to the reflective mirror of the lens assembly. The light is further reflected by the reflective mirror onto the chips of the solar energy converter and converted into electric energy.
The lens assembly includes a reflective mirror and a glass plate. The output end of the light guiding medium is connected to a top of the lens assembly, and the light splitter is located at a center of the glass plate. The light splitter may be a pyramidal light splitter or a curved light splitter to reflect incident light. And, the light guiding medium may be an optical fiber cable or a light guiding plate or other functionally equivalent elements.
The light guide may further include an optical filter arranged in front of the input end of the light guiding medium for filtering out infrared light from the focused light to minimize heat contained in the focused sunlight.
The present invention provides at least the following advantages:
The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein
The concentrator 10 functions to collect and focus a light source 40, such as sunlight. Alternatively, the light source 40 may be other light similar to sunlight and projected onto the concentrator 10. The concentrator 10 may be a focusing lens 11, a reflective mirror, a thin-film concentrator, or any other functionally equivalent concentrating elements. In the present invention, at least one focusing lens 11 is adopted to receive and focus sunlight.
The light guide 20 is positioned at the focal point of the concentrator 10. The focused light can be fully coupled to the input end of the light guide 20 to propagate through the light guide 20 to the output end of the light guide 20. The light guide 20 includes at least one light guiding medium 21 and at least one lens assembly 22 connected to the light guiding medium 21. The lens assembly 22 consists of a reflective mirror 25 and a glass plate 24. The output end of the light guiding medium 21 is extended to the inner side of the reflective mirror 25 of the lens assembly 22 and aligned with a center of the glass plate 24. When the light propagates through the light guiding medium 21 to the lens assembly 22, the light projects on and is reflected by the reflective mirror 25 onto at least one photovoltaic cell chip 31 of the solar energy converter 30, and converted into electric energy.
The light guide 20 may further include at least one light splitter 23, and the output end of the light guiding medium 21 is aligned with the light splitter 23. When the focused light projects from the output end of the light guiding medium 21 onto the reflective mirror 25 and is then reflected by the reflective mirror 25 onto the chip 31 of the solar energy converter 30, the light is converted into electric energy. The light splitter 23 may be a pyramidal or a curved light splitting medium.
The light guiding medium 21 may be an optical fiber cable 27 as shown in
The solar energy converter 30 is arranged at the output end of the light guide 20 for receiving the light projected from the light guide 20 and converting the received light into electric energy. In the present invention, the solar energy converter 30 is a concentration photovoltaic cell.
Alternatively, the pyramidal light splitter 23 may be replaced with a curved light splitter (not shown) to provide the same light reflecting effect.
The concentration photovoltaic cell system with light guide according to the present invention provides at least the follow advantages:
The present invention has been described with some preferred embodiments thereof and it is understood that many changes and modifications in the described embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.
