JP2011129847A - Reflecting concentrated solar power generating module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflecting concentrated solar power generating module that is more advantageous in terms of space-saving and cost performance compared to a conventional reflecting/condensing solar power generation system. <P>SOLUTION: A long and narrow solar cell is disposed parallel with a bucket-shaped reflection mirror having an arcuate section such that the solar cell is near a point separated from the reflection mirror across a distance equivalent to the half of the radius of the reflective mirror arcuate shape. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a reflective concentrating solar power generation module having a bowl-shaped reflecting mirror, and more specifically, a reflective concentrating solar that saves space and has a higher cost performance than a conventional reflective concentrating solar power generation device. The present invention relates to a photovoltaic module.

One type of photovoltaic power generation system that uses photovoltaic elements is a fixed type that generates solar power directly by installing solar cells with photovoltaic elements arranged without a solar condensing mechanism. It is becoming popular. However, the fixed solar power generation system has a small amount of power generation per area of the expensive solar cell, and remains a problem in terms of power generation cost.

On the other hand, it is possible to obtain a large amount of power generation with a small-area solar cell, and the sunlight is linearized using a kamaboko-shaped elongated convex lens or a bowl-shaped reflector having a parabolic cross section. A concentrating solar power generation system that collects light (for example, see Non-Patent Document 1), and further, a uniaxial tracking type system that adds a mechanism for tracking the movement of the sun of the day to the concentrating solar power generation system. In recent years, a concentrating solar power generation system (see Non-Patent Document 2) has attracted attention.

KEC information NO, 201 p. 17-18 2007 R & D News Kansai Special Issue p. 36-37

In a conventional concentrating solar power generation system, a solar cell is arranged near the focal point of a reflecting mirror or the like in order to improve power generation efficiency, so a large space corresponding to the focal length of the reflecting mirror or the like is required. It becomes the device. In addition, since the single-axis tracking type concentrating photovoltaic power generation system described above does not cope with changes in solar altitude due to the season, some of the expensive photovoltaic elements become idle depending on the season, and cost performance Leave a complaint. In order to eliminate the idle state of photovoltaic devices and increase the power generation efficiency throughout the year, in addition to a mechanism that tracks the movement of the sun in the day, a biaxial tracking type reflection that has a mechanism to track changes in the solar altitude due to the season A concentrating solar power generation system is also considered. However, the two-axis tracking type complicates the tracking mechanism and further increases the cost.

An object of the present invention is to provide a reflective concentrating solar power generation module that saves space and has high cost performance as compared with a conventional reflective concentrating solar power generation system.

The present inventor uses, instead of a saddle type reflector having a parabolic focus in a cross section in a reflective concentrating solar power generation system, a saddle type reflector having a cross section having no focal point and a circular arc, It has been found that the above object can be achieved if the light receiving surface of the solar cell is installed in the vicinity of a half of the radius, and the length of the light receiving surface of the solar cell is slightly shorter than the length in the longitudinal direction of the reflecting mirror. Completed.

That is, the present invention according to claim 1 is a reflective concentrating solar power generation module in which a saddle-shaped reflecting mirror having a circular cross section and a solar cell elongated in parallel with the reflecting mirror are provided. The battery is installed in the vicinity of a half of the radius of the reflecting mirror.

The present invention according to claim 2 is characterized in that, in claim 1, the light receiving surface of the solar cell is a distance (e) expressed by the following mathematical formula 1 from the reflecting mirror curved surface.

The present invention according to claim 3 is the saddle type reflecting mirror according to claim 1 or 2, wherein the length of the arc (l) is expressed by the following mathematical formula 2.

The reflective concentrating solar power generation module of the present invention according to any one of claims 1 to 3 is a conventional reflective condensing concentrator formed by using a vertical reflector having a parabolic cross section and arranging a solar cell in the vicinity of the focal point thereof. Compared to the type solar power generation system, it can realize space saving and low cost, and is therefore suitable for a large-scale solar power generation apparatus capable of obtaining a larger amount of power generation.

The present invention according to claim 4 is characterized in that, in claims 1 to 3, the width (d2) of the light receiving surface of the solar cell is not more than 1/5 of the width (d2) of the reflecting mirror.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the length (L2) of the light receiving surface of the solar cell is a size represented by the following mathematical formula 3.

The present invention according to claim 6 is the tracking according to any one of claims 1 to 5, wherein the entire apparatus is installed in parallel with the earth axis, and the movement of the sun is tracked by rotating around the rotation axis parallel to the earth axis. It has a mechanism.

In addition to the present invention according to any one of claims 1 to 3, according to the reflective concentrating solar power generation module according to any one of claims 4 to 6, a solar cell (photovoltaic element) that is idle throughout the year. It is possible to provide a solar power generation device with high cost performance that is free from any problem.

Hereinafter, the reflective concentrating solar power generation module according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing the concept of the photovoltaic power generation module of the present invention. The cross section of the reflecting mirror M is a part of a circular arc, and is a symmetrical bowl-shaped concave mirror with the point O at the center. When sunlight is irradiated from the upper side of the figure, the light beam is reflected by the mirror surface and goes toward the center line (Y axis) connecting the centers R and O of the arc. When the cross section of the reflector is a parabola, the reflected light is collected at one focal point, but there is no focal point in the case of the circular reflector used in the present invention.

Here, it is assumed that the line connecting the point A and the center R on the arc is 45 ° with the center line R to O (Y axis) (one-side center angle 45 °). A light ray incident from above in parallel with the Y axis is reflected at the point A, changes its direction by 90 °, and intersects the Y axis at the point a. Similarly, a light beam reflected at a point B having a central angle of 30 ° on one side is reflected at an angle of 60 ° and intersects the Y axis at a point b. The central angle of one side of the point C is 25 °, and the intersection of the reflected light from the point D, the point F, and the point G in increments of 5 ° and below is c, d, f, and g, respectively. When the coordinates (x, y) of each point are calculated, Table 1 is obtained. However, the radius of the arc is 1.0. The numbers entered in the columns y = 0.40, y = 0.45, and y = 0.50 are solar cells at heights (y) 0.40, 0.45, and 0.50. Represents the X coordinate that the reflected light crosses when is installed. Since the reflected light from the point A described above crosses the Y axis horizontally at the position of 0.293, it does not reach the position of y = 0.40 or above.

Consider the case where the solar cell E is installed at the position of y = 0.40 with the reflection surface facing. Reflected light from the reflecting surface with a central angle of 30 ° or less gathers inside approximately 0.06. Since the X coordinate of the point B having the central angle of 30 ° is 0.50, the reflected light on the inner side of the point B gathers on the inner side of 0.06 at the position of y = 0.40, which is about eight times as much. Be lit. Strictly speaking, since light does not reach the shaded portion of the solar cell, the actual magnification is smaller than this.

Next, at the position of y = 0.45, 0.047 that the reflected light from the point B crosses is the maximum (absolute value), so the light collection rate is approximately 10 times. That is, when the vertical reflector of the present invention whose cross section is a part of a circle is used, it is possible to collect light about 10 times.

By the way, the reflected light from the point B is incident on the flat solar cell in the vicinity of the point P having a half radius at an angle of 30 °. At this angle, a significant proportion of the reflected light may re-reflect on the solar cell surface and not contribute to power generation. In order to avoid this, a smaller center angle, for example, an arc within point D (center angle 20 °), may be used as the reflecting surface. Which range of the arc is used as the reflection surface may vary depending on the degree of re-reflection of the reflected light on the surface of the solar cell and where the solar cell E is placed near the point P. In any case, it is possible to use reflected light in the range of arcs B to B ′ at the maximum (at this time, the central angle on one side is 30 °), but a range smaller than that may be used. Therefore, as the reflecting mirror, the length of the arc (l) may be a size represented by the following formula 2.

Next, consider another case. Consider D to D ′ having a central angle of 20 ° as a reflector arc. The solar cell is placed parallel to the reflecting mirror at a height of 0.45 on the Y axis. Since the reflected light at this position is collected in a range of about 0.019 at the maximum, 0.02 (one side) is sufficient for the width of the solar cell. Since the X coordinate of the point D is 0.342, the condensing magnification is 18 times (17 times excluding the shaded portion). When the central angle on one side is 20 °, even if the solar cell is placed at a height of 0.50, that is, at a position P that is ½ of the radius, the reach of the reflected light is 0.027 (absolute value). Therefore, the light collection magnification is about 12 times. As can be seen from this, the position of the solar cell may be slightly larger than 0.50.

That is, in the present invention, the width of the solar cell is 1/5 or less of the width of the reflector, and the solar cell is installed within the distance (e) represented by the following formula 1 from the curved surface of the reflector. Performance of 5 times or more of light collection can be ensured.

FIG. 2 shows an embodiment of the reflective concentrating solar power generation module of the present invention. The reflecting mirror M is a circular arc with a cross section of a central angle (both sides) of 40 ° with a radius of 1.46 m. At this time, the width (string) of the reflecting mirror M is 1.0 m. A solar cell having a width of 0.056 m is placed facing a reflecting mirror at a position (E) 0.66 m from O on a line connecting the center O of the reflecting mirror and the center R of the circle. When sunlight enters the reflecting mirror from a direction parallel to O to R, the reflected light is condensed approximately 17 times at the position of the solar cell, and power is generated. As can be seen from FIG. 2, by selecting the position of the solar cell E in the vicinity of the point P having a radius of 1/2, it is possible to freely design a solar cell having an intended concentration ratio.

One problem with concentrating solar cells is that the higher the concentration factor, the more concentrated the solar heat, and the higher the solar cell temperature, the lower the power generation efficiency. For this reason, various heat removal devices have been devised, but it is also an option to provide a design that eliminates the problem of heat removal by suppressing the light collection magnification to about 10 times without unnecessarily increasing the concentration factor. In that sense, such a low-magnification concentrating power generator is also sufficiently meaningful. In addition, it cannot be overemphasized that the heat removal technique already known can be applied to this invention as needed.

Tracking to the diurnal movement of the sun can be achieved by installing the concentrating solar power generation device of the present invention parallel to the earth axis and rotating it from east to west around a rotation axis parallel to the earth axis. This will be explained with reference to FIG. 2. The central axis O of the reflecting mirror is set parallel to the ground axis, and the entire device including the solar cell E is rotated from east to west around this axis. The center of rotation is not limited to O, and can be selected considering the center of gravity of the entire apparatus. At 6 o'clock in the morning, the center of the reflector faces the eastern horizontal direction. It is the sunrise time for spring and autumn. Needless to say, it heads directly above (south south) at noon and heads west at 6:00 in the evening. Here, time is not the standard time of Japan, but the absolute time of the land, when the sun goes south in the land and noon. In the northern hemisphere, the sun has already risen at 6 am in the summer, but the orientation of the reflector at 6 am can be the same regardless of the season. If you want to use sunlight before 6 o'clock, you may start tracking the reflector from a slightly downward angle and at sunset until 6 o'clock. After tracking until sunset, the reflector is returned to the starting position the next day during the night.

Next, with reference to FIG. 3, a concept corresponding to a change in solar altitude due to the season will be described. M is the center line of the saddle type reflector, and E is the position of the solar cell. M and E are parallel and parallel to the ground axis. That is, the angle α with respect to the horizontal plane is equal to the latitude of that point on the earth (α is negative in the Southern Hemisphere). In spring equinox and autumn equinox, sunlight enters the reflecting surface perpendicularly, is reflected by the reflecting mirror, and is applied to the solar cell E. On the other hand, at the summer solstice, sunlight is incident at an angle β tilted 23 degrees 26 minutes north from this vertical line, and is reflected in the direction tilted south by the same angle. The winter solstice is exactly the opposite. Here, β is the inclination of the earth axis with respect to the revolution plane of the earth around the sun, and is the same as the latitude of the north regression line.

言いかえると、太陽電池Ｅの長さＬ２を基準にすれば、下記数式４のように反射鏡の長さＬ１をそれより若干長くすれば良い。

It is expected that it will be very difficult to change the angle of the device up and down (north-south) following the seasonal change in solar altitude as the device becomes larger. In addition, complicated control is required to follow the movement of the sun at the same time, leading to high costs. What is important here is that the length L1 (A-B) of the reflector and the length (ab) of the solar cell are the same, the portion of b to s in the summer solstice, and the portion of a to w in the winter solstice. It is that no reflected light hits. In other seasons except spring and autumn, the light received in this part is less than in other parts, but the amount of power generated in this part decreases. As described above, the amount of light received varies greatly depending on the seasons at both ends of E, but the section (L2) from w to s excluding that can receive the reflected light evenly in any season. That is, if the light receiving portion (solar cell E) is shorter than L2 with respect to the reflective surface L1, that is, the length expressed by the following mathematical formula 3, the sun that is idle throughout the year regardless of the change in solar altitude due to the season. There is no battery (photovoltaic element), and uniform power generation is always possible.

In other words, if the length L2 of the solar cell E is used as a reference, the length L1 of the reflecting mirror may be slightly longer as shown in the following formula 4.

According to the present invention, it is impossible in principle to use all the sunlight collected by the reflecting mirror. However, the loss can be made as small as possible and the utilization efficiency can be made as large as possible (close to 1). Here, the utilization efficiency ε is determined by the ratio L2 / L1 between the length of the solar cell and the length of the reflecting mirror. To increase this, the ratio of the distance e to the solar cell with respect to the length L1 of the reflecting mirror is made as small as possible. Just do it. When geometrically analyzing FIG. 3, if e is 1/10 of L1, the utilization efficiency ε is approximately 0.91. 1/20 is 0.96, and there is no practical problem.

By arranging a plurality of the reflective concentrating solar power generation modules of the present invention in parallel, a larger amount of power generation can be obtained. FIG. 4 is a cross section in which three units are arranged in parallel as an example (here, one module unit is called a unit). Consider the case of collecting sunlight with a total width of 2 m. In the example of FIG. 2, when the width of the reflecting mirror is 2 m, the distance e from the center of the reflecting mirror M to the solar cell E is 1.32 m. On the other hand, when three units are arranged in parallel, the total width of one unit is 0.67 m, and the distance e to the solar cell E is 1/3, which is approximately 0.44 m. If the lengths L1 of the units (reflecting mirrors) are the same, for example, 5 m, the reflected light utilization efficiency ε (L2 / L1) is closer to 1 when e / L1 is smaller as described above. Therefore, it is possible to increase the efficiency of the device with respect to changes in solar altitude due to the season by arranging three units. The number of units to be arranged is determined by comparing the complexity of the apparatus with the efficiency gain obtained. Tracking to the sun's diurnal motion when a plurality of units are arranged in parallel can be achieved by rotating the entire plurality of units around an axis parallel to the ground axis, as in the case of a single module.

The invention's effect

The reflective concentrating solar power generation module according to the present invention is sufficient because the installation location of the solar cell is in the vicinity of ½ of the radius of the arc of the reflector, even though the reflector does not have a clear focus. It is characterized by being able to achieve a condensing magnification. Thereby, space saving and low cost are realized compared with the conventional reflective concentrating solar power generation system. Furthermore, by making the length of the light receiving surface of the solar cell shorter than the length of the reflecting mirror, it is possible to provide a solar power generation device with high cost performance without a solar cell (photovoltaic element) that is idle throughout the year. Is.

The conceptual diagram explaining the reflective condensing type photovoltaic power generation module of this invention The cross-sectional view which shows one embodiment of the reflective condensing type photovoltaic power generation module of this invention Sectional drawing of the vertical direction of the reflective condensing type photovoltaic power generation module of this invention Sectional drawing which connected 3 units | sets of the reflective condensing type photovoltaic power generation modules of this invention

E: Solar cell light receiving surface, M: Reflector, P: Position of half of radius of reflector, R: Center of reflector arc, e ... Reflector to solar cell To the light receiving surface, L1... Length in the longitudinal direction of the reflecting mirror, d1... Width of the reflecting mirror, L2... Length in the longitudinal direction of the solar cell, d2.

Claims (6)

A reflective concentrating solar power generation module comprising a saddle-shaped reflecting mirror having a circular cross section and an elongated solar cell parallel to the reflecting mirror, wherein the solar cell is 1 / of the radius of the arc of the reflecting mirror 2. A reflection concentrating solar power generation module, which is installed in the vicinity of 2. The reflective concentrating solar power generation module according to claim 1, wherein the light receiving surface of the solar cell is a distance (e) represented by the following formula 1 from the center of the arc of the reflecting mirror.

The reflective concentrating solar power generation module according to claim 1 or 2, wherein the length (l) of the circular arc of the cross section is a vertical reflector represented by the following formula 2.

The reflective concentrating solar power generation module according to any one of claims 1 to 3, wherein the width (d2) of the light receiving surface of the solar cell is 1/5 or less of the width (d1) of the reflecting mirror. The reflective concentrating solar power generation module according to any one of claims 1 to 4, wherein the length (L2) of the light receiving surface of the solar cell is a size represented by the following mathematical formula 3.

The reflective concentrating sun according to any one of claims 1 to 5, further comprising a tracking mechanism that installs the entire apparatus parallel to the earth axis and rotates the sun around a rotation axis parallel to the earth axis to track the movement of the sun during the day. Photovoltaic module.

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