JPH0320074B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a concentrating solar power generation device.

Concentrating solar power generation devices generally generate solar power by concentrating sunlight irradiated onto the ground using a lens or reflecting mirror, and placing, for example, a solar cell element at the focal point (or focal line). It is possible to significantly increase the amount of power generated per unit area of the solar cell element, and when compared with a non-concentrating solar power generation device, it is possible to obtain the same generated power.
This has the advantage of requiring fewer solar cell elements. In order to obtain a light concentrating system at low cost, these concentrating solar power generation devices generally use Fresnel lenses made of transparent plastic materials, especially those with low concentrating power of about 10 to 50 times. A linear Fresnel lens is used for the power generator. On the other hand, since concentrating solar power generation devices utilize only the direct sunlight that is irradiated onto the ground, they must track the sun as it changes time and position. The position of the sun changes due to temporal movement corresponding to the rotation of the earth and seasonal movement corresponding to the revolution of the earth. Therefore, in order to keep the concentrating solar power generation device directly facing the sunlight, it is necessary to prepare a tracking mechanism, for example, with two axes, which can track the sun according to the time and declination. However, the two-axis tracking mechanism has a complicated structure and a complicated tracking control method, so it is difficult to use a concentrating solar panel with high light concentration (e.g., 100 to 1000 times the light concentration) that requires high tracking accuracy. Although it is essential for photovoltaic power generation devices, it is not economical for photovoltaic power generation devices with lower light concentration. Therefore, conventionally, a method of tracking only one axis, east and west, as shown in FIG. 1, in which the tracking mechanism is omitted, has been common. In FIG. 1, 1 is a solar cell element, 2 is a linear Fresnel lens, 3 is a movable frame for fixing the solar cell element and the linear Fresnel lens, and 5 is a movable frame for fixing the solar cell element and the linear Fresnel lens.
and 6 indicate a support including a bearing for installing the movable frame at an angle, and 4 indicates the center of rotation of the movable frame. In the same figure, the movable frame is installed by a support to face due south as shown in the direction S, and the movable frame is angularly controlled using the center of rotation. It can rotate and track sunlight.

On the other hand, the movable frame for holding the linear Fresnel lens and the solar cell element together must be designed to be strong in consideration of wind pressure, which increases the weight of the materials used. The pillars, including the bearings for support, are also becoming larger, and in order to stably track the sun over a long period of time, it is unavoidable to use strong materials. Ta. The biggest reason for this is that the flat linear Fresnel lens, which is most susceptible to wind pressure, was mounted on the movable mechanism.

That is, according to the conventional method, since the linear Fresnel lens and the solar cell element were mounted as one body on the movable frame, the movable frame and the pillars including the bearings for supporting the movable frame had to be strengthened. As a result, the structure of the bearing part and the drive system became larger, which inevitably increased the cost of materials.Furthermore, there were restrictions on the dimensions of the movable frame's constituent units. There was a major drawback in that it occurred.

The present invention can eliminate such conventional drawbacks and provide a concentrating solar power generation device with a simple structure.

That is, according to the present invention, the slope is fixed in a southward direction.
Concentrated solar light consisting of a linear Fresnel lens and a solar cell element equipped with a position control mechanism so as to align with the focal line of the linear Fresnel lens, which moves over time during the day as the sun moves. In the power generation device, the fixed inclination angle θ between the linear Fresnel lens and the horizontal plane is −24°<θ<+ with respect to the latitude of the installation location of the concentrating solar power generation device.
24°, and the position of the solar cell element is
centered on the center line of the linear Fresnel lens,
When moving on a circumference with a radius corresponding to the focal length of the linear Fresnel lens, and when the linear Fresnel lens is centered, the incident angle α of sunlight with respect to a perpendicular passing through the center of the linear Fresnel lens, and the angle of incidence α from the center line of the linear Fresnel lens. The angle β formed by the straight line leading to the solar cell element is α = β = 0 when the sun is in the sky, and when it is not in the sun,
A concentrating solar power generation device is obtained, which is characterized in that it is controlled so that 0.9α<β<1.3α.

The Earth's axis of rotation is tilted at an angle of approximately 23.45° with respect to its axis of revolution. Therefore, if the inclination angle is set to the same value as the latitude of the observation point on Earth, sunlight will enter the lens surface at right angles at the midpoint of the vernal and autumnal equinoxes. In addition, if the tilt angle is set by +23.45° and -23.45° relative to the latitude, sunlight will enter the lens surface at right angles at the midsummer time of the summer solstice and winter solstice, respectively, and this tilt angle can be continuously controlled. What we do is nothing but elevation-angle tracking of the sun. The present invention is characterized by fixing this elevation angle to a predetermined angle, and depending on the season, the inclination angle can be changed to -24°<θ<+24°.
By setting the power within this range, more efficient power generation becomes possible. Note that the azimuth angle A and the altitude angle h of the sun are determined by the following formula.

sin h=sin Ψ・sin δ +cos Ψ・cos δ・cos t sin A=cos δ・sint/cos h where Ψ: latitude of observation point t: hour angle δ: declination As mentioned above, the inclination where the lens is located Since it is fixed at an angle, in the height direction of the lens,
When sunlight is incident on the lens obliquely, it is incident at right angles only when the sun is in the sky, and obliquely at other times.The focal line width and the distribution of sunlight energy within the focal line width change with the angle of incidence. do. In one example of experimental results, 0.9α<β<1.3α was optimal.

FIG. 2 shows a perspective view of an embodiment of the present invention.

In FIG. 2, 1 is a solar cell element, 2 is a linear Fresnel lens, 3 is a fixing frame for tilting and fixing the linear Fresnel lens, 7 and 7' are both ends c of the center line 8 of the linear Fresnel lens, This is an arm for causing the solar cell element to move circumferentially around c'.

In the figure, the linear Fresnel lens is fixed by a fixed frame at an angle of inclination θ with respect to the horizontal plane h, facing directly as indicated by s. On the other hand, the solar cell element 1 is moved around the center points c and c' of the linear Fresnel lens by the arms 7 and 7', and in the morning is a
direction, and the afternoon direction is controlled to move on the circumference in the p direction. Light incident obliquely on a linear Fresnel lens forms a focal line near the optical axis passing through the center 8 of the linear Fresnel lens, and the position of the focal line changes depending on the position of the sun, which changes with time. also changes. The situation is shown in Figure 3.

In FIG. 3, 1 is a solar cell element, 1' is a heat sink, 2 is a linear Fresnel lens, and L is incident sunlight. FIG. 3a shows an example in which sunlight is incident on the linear Fresnel lens at a right angle (that is, incidence at the center of the sun), and FIG. 3b shows an example in which sunlight is incident at an oblique angle.

In the same figure, the focal line is exactly located on the perpendicular line to the center of the linear Fresnel lens at the time of culmination, but
When sunlight is incident at an angle, the focal line does not necessarily line up on the optical axis passing through the center of the linear Fresnel lens.In other words, the angle α between the perpendicular to the linear Fresnel lens and the incident sunlight is The angle β formed by the straight line from the center of the linear Fresnel lens to the solar cell element is not always equal. The reason for this is that when sunlight is incident obliquely, the focal line width changes and the intensity distribution of the focused light becomes uneven.The deviation is due to the angle of incidence of sunlight α
It is not a constant value. However, the angle β
By selecting the optimum value of in the range of 0.9α<β<1.3α for the incident angle α, the solar cell element can be placed at the peak value of the intensity distribution of the concentrated light, resulting in good solar cell output. It becomes possible to obtain. On the other hand, the installation angle θ of the frame is adjusted to - according to the declination, relative to the latitude of the installation location of the concentrating solar power generation device.
It is unnecessary to explain that by taking the value 24°<θ<+24°, even better solar cell output can be obtained.

Furthermore, it is clear that the above explanation can be easily applied to a north-south single tracking type concentrating solar power generation device. In other words, even when applied to north-south uniaxial tracking, since oblique incidence on the lens is unavoidable, it is optimal to position the solar cell element at the maximum energy distribution of the focused light. Similar angle control is optimal when using lenses.

[Brief explanation of the drawing]

Fig. 1 is a perspective view schematically showing a conventional east-west 1-axis tracking type concentrating solar power generation device, Fig. 2 is a perspective view showing an embodiment of the present invention, and Fig. 3 is a linear Fresnel lens. FIG. 2 is a schematic diagram showing the incident light angle and the state of condensation. In the figure, 1...solar cell element, 1'...
...Heat sink, 2...Linear Fresnel lens, 3...
Frame, 4... Frame rotation center line, 5, 6...
. . . pillar including a bearing portion, 7 . . . arm, 8 . . . linear Fresnel lens center line.

Claims (1)

[Claims] 1. Concentrating sunlight equipped with a linear Fresnel lens tilted and fixed to the south and a position control mechanism that moves the solar cell element as the sun moves during the day so that the solar cell element coincides with the focal line of the linear Fresnel lens. In the power generation device, the fixed inclination angle θ between the linear Fresnel lens and the horizontal plane is −24°<θ< with respect to the latitude of the installation location of the concentrating solar power generation device.
+24°, when the solar cell element moves on a circumference centered on the center line of the linear Fresnel lens and has a radius corresponding to the focal length of the linear Fresnel lens, and when the linear Fresnel lens is centered, the linear Fresnel lens The relationship between the incident angle α of sunlight with respect to the perpendicular passing through the center and the angle β formed by the straight line from the center line of the linear Fresnel lens to the solar cell element is α = β = 0 when the sun is in the sky. 0.9α except for time
A concentrating solar power generation device characterized by <β<1.3α.