JPS6131853A - Method and device for tracking type solar light electric generation - Google Patents

Abstract

PURPOSE:To improve light collecting efficiency by a method wherein the angle of a panel is adjusted intermittenly only in the North-South direction. CONSTITUTION:Sun tracking light detectors 10, 11 are attached to the panel in the north-south direction. When the altitude of sun is lower than the slant angle of the panel, direct sun beams are projected against the light detector 10 but the light detector 11 is in the shadow of the panel. The output of the light detector 10 begins to increase from a time when the light begins to shoot the detector 10 and a tracking mechanism is moved by the leading edge signal of the detector to change the slant angle of the panel. When the angle of the panel approaches vertical with respect to the incident light of the sun, the light detector 11, equipped at the north side of the panel, begins to receive the light of the sun and the electric output thereof is increased. When the angle of panel becomes vertical with respect to the incident light of sun, the outputs of the detectors 10, 11 becomes equal. When the electric outpts of both detectors 10, 11 become equal after comparison, a signal is outputted to stop the operation of the tracking mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a solar power generation system, and more particularly to a solar power generation method and apparatus for automatically changing the inclination angle of a solar cell in accordance with the solar altitude.

[Background of the invention]

For example, a solar power generation system that directly converts solar energy into electrical energy, such as a solar cell, has a very high cost per unit output compared to other thermal power, hydropower, nuclear power generation, etc. The main reasons for this are as follows.

Solar energy density is low, and the energy conversion efficiency of solar cells is only about 10%. Moreover, solar cells are quite expensive, and currently a single crystal solar cell costs about 1,000 yen per IW. Therefore, in photovoltaic power generation systems, it is important to reduce the manufacturing cost of solar cells and to increase light collection efficiency. One way to increase light collection efficiency is to install the battery at a certain angle from the ground.

FIG. 15 shows an example of such a conventional method.

In the figure, 1 is sunlight and 2 is a solar panel.

3 is a frame that supports the panel. The angle of inclination of the battery is generally equal to the latitude of the installation location. This is because choosing an angle perpendicular to the solar altitude at the vernal and autumnal equinoxes will increase the annual amount of incident solar radiation.

However, if the battery inclination angle is constant, the solar altitude and azimuth change depending on the time and season, so the normal component of the amount of solar radiation incident on the panel decreases. Therefore, in order to increase the amount of solar radiation that enters the panel, it is being considered to have the panel track the sun.

In tracking solar power generation systems, there are reports on systems that simultaneously track battery panels in both east-west and north-south directions.
nal 5olar energy 5ociety,
9o1ar World Congress, p.
erth, 1983; Tne ASI One
-Megawatt Photovoltaicpow
er plant. In this example, the battery panel is made to track the sun simultaneously in east-west and north-south directions, and a computer is used to calculate changes in the panel angle. Figure 16 shows an outline of the tracking solar power generation system. 4 is a calculator, and 5 is a DA or AD converter. The solar altitude and direction angle are calculated by the calculator 4 according to the time and season, and signals corresponding to the changes in angle of the battery panel in the north-south and east-west directions per unit time are given to the gear 7.9 through the D-Ai converter 5. The gear 6.8 is moved to simultaneously change the east-west and north-south angles of the battery panel 2 to track the sun.

Such conventional solar tracking methods have the following drawbacks.

(1) A solar tracking computer is required, making the entire device quite large.

<2) Since a D-A converter and the like are used, the control device becomes complicated.

(3) Since the battery panel only has one support, it is difficult to protect the panel against strong winds such as typhoons.

(4) Power is required to track the sun even on cloudy or rainy days when light collection efficiency is low.

On a sunny day, the direct radiation reaches 50 to 60 inches of the total solar radiation, so when tracking the sun, the direct radiation can be used effectively, and the efficiency is 1 It reaches 4 to 6 times more per day. However, on cloudy or rainy days, most of the total solar radiation is scattered light, so even if the sun is tracked, it will not change much compared to keeping the battery panel tilt angle constant, and the light collection efficiency will not increase.

[Purpose of the invention]

The purpose of the present invention is to provide a tracking solar power generation system that
It is an object of the present invention to provide a power generation method and a power generation device that increase light collection efficiency by causing a panel to track the sun intermittently.

[Summary of the invention]

As mentioned above, the problem with the conventional technology is that when the panel inclination angle is kept constant, the light collection efficiency is poor, and even when tracking the sun, the tracking mechanism becomes quite complex. Therefore, the present invention provides a device that easily and intermittently tracks the sun to increase light collection efficiency. The tracking cycle of intermittent solar tracking can be selected arbitrarily, and if the tracking cycle is short, for example 1
In the case of once a day, in order to reduce power, we provide a device that performs tracking only when it is sunny, increasing light collection efficiency.

@1719A shows an example of the measurement results of the amount of solar radiation per day in cloudy and sunny conditions. In cloudy and z conditions, the total solar radiation is low and there is almost no direct radiation, so there is only scattered solar radiation. On the other hand, when it is sunny, the total solar radiation is high, and the proportion of the direct radiation to the total solar radiation also increases. For the cloudy and sunny cases in Figure 17 Bl-tA, the panel inclination angle is constant.

This is the measured value of the intensity of solar radiation incident on a single area of the nokunel when tracking in the east-west direction and the north-south direction. In this case, the panel inclination angle was assumed to be equal to the declination angle for east-west direction tracking.

In addition, in north-south direction tracking, the tunnel azimuth was set to o'B. If it's cloudy, move east-west.

Even when tracking in the north-south direction, the amount of solar radiation incident on the panel does not change even if the panel inclination angle is kept constant.

This is because very little of the total solar radiation is directly achieved, and the effect of tracking does not appear.

On the other hand, when it is sunny, the amount of solar radiation incident on the panel increases by two times in east-west direction tracking, and by four times in north-south direction tracking, compared to the case where the panel inclination angle is constant. It was also found that, even on sunny days in other seasons, there are many days when tracking in the north-south direction generally improves light collection efficiency than tracking in the east-west direction. Therefore, here, the more effective north-south direction is adopted as the tracking direction.

Figure 18 shows the measurement results of the annual amount of solar radiation that enters the panel by tracking cycle. The tracking method is north-south direction tracking.

There is almost no difference in light collection efficiency between continuous tracking and tracking once a day on a sunny day. In addition, once a day tracking means that the solar altitude changes little during the day when the amount of solar radiation is high, so the panel inclination angle is corrected to be perpendicular to the solar altitude around noon. means. If tracking is performed once a day on a sunny day, the light collection efficiency will improve by about 15 inches per year compared to when the panel tilt angle is constant. Also, 1 month 1
When tracking in the north-south direction, the light collection efficiency improves by about 9 inches compared to when the panel tilt angle is constant. Here, tracking once a month means correcting the panel inclination angle to be perpendicular to the solar altitude once a month (for example, at the beginning or middle of the month). The measurement results described here were measured in regions in Japan where the amount of direct solar radiation is relatively low, and the effect of improving light collection efficiency is even greater in regions where the amount of direct solar radiation is large.

The present invention provides a tracking device that is capable of tracking once a day only on sunny days, rather than continuous tracking, in order to increase the effect as much as possible with less power. Furthermore, by developing this, we also provide a device with a variable tracking period so that it can meet the need for a simple tracking method even if its effectiveness is low.

FIG. 19 is a diagram showing temporal and seasonal changes in solar altitude and azimuth, which are important for understanding the principle of the present invention. This value is at a declination of 30 degrees. As you can see from this value, the solar altitude does not change much during the day. For example, on the winter solstice, there are only changes within the range from 8 a.m. to 4 p.m. Also, even on the summer solstice, the temperature change from 9 a.m. to 3 p.m. is about 10 degrees.

FIG. 20 is an example of measuring changes in solar radiation over time on a sunny day. In the morning and evening, the amount of solar radiation decreases rapidly. Therefore, as an effective tracking method for effectively utilizing the amount of direct solar radiation by tracking the sun, it is sufficient if the panel is perpendicular to the sunlight only during times when the amount of solar radiation is high. Since the solar altitude is almost constant during this time, there is no need for continuous tracking, and it is only necessary to adjust the slope angle once a day.The solar altitude at the summer and winter solstice is constant, so (90° - Declination) +23°27', (90' - Declination) -23°27'÷
Yes, it does not change from year to year.

[Embodiments of the invention]

FIG. 1 is a diagram illustrating an embodiment of the present invention.

Solar tracking photodetectors 10 and 11 are installed in the north-south direction of the panel, and tracking is started and stopped by electrical signals from the detectors.

FIG. 2 shows how to install the photodetector and the photodetector section. Install the detection part with the slit surface aligned with the panel surface,
The width of the slit 13 in the east-west direction is widened so that the light enters the detection section for a certain period of time. A photocell 12 is attached to the bottom of the slit as a light receiving surface.

As is clear from FIG. 3A, the relationship between the seven otocells 12 and the slits 13 is different between the detectors 10 and 11.

Note that the detectors 10 and 11 do not necessarily have to be arranged at the top and bottom of the panel, but may be arranged side by side on the top or bottom. FIG. 3B shows the time variation of the electrical signal from the photocell.

As shown in FIG. 1, when the solar altitude is lower than the panel inclination angle, direct sunlight hits the photodetector 10, and the detector 11 is in the shadow. Therefore, the temporal changes in the electrical outputs of 10 and 11 are as shown in FIG. 3B. That is, the photodetector 10
The output starts to rise from the time when the detector 11 starts being exposed to light, but the output from the detector 11 which is in the shadow is low. The tracking mechanism is moved by the rising signal from the detector 10 to change the panel inclination angle. When the panel becomes perpendicular to the incident solar light, light begins to enter the photodetector 11 installed on the north side of the panel, and the electrical output from the photodetector 11 increases. The solar output from 11 degrees becomes equal. When the electrical outputs of the rain detectors 10 and 11 are compared and become equal, a signal is output and the tracking mechanism is stopped. Tracking begins only when sunlight is directly incident on the photodetector and stops when the panel becomes perpendicular to the incident light, so this device can track the sun intermittently only on sunny days. The tracking start time can be made earlier than noon by installing the photodetectors to, ii at an angle from the panel surface. Note that noon here does not refer to Japan Standard Time, but refers to the time when the sun reaches its midpoint locally, which is different in Hokkaido and Okinawa.

FIG. 4 shows an example of a circuit related to turning on and off the electric power source in the case of intermittent tracking. 14 is the power supply, P to 15, N to 16
The characters marked with and indicate the high-voltage side and low-voltage side of the power supply, respectively.

Moreover, Zl and Z2 are the photodetectors 10. shown in FIG.
11 represents a switch that is operated, and Z3 represents a switch that is operated by the output of the AND circuit of the photodetector 610.11. In the circuit diagram, the contact cloth and lines drawn on the left side represent contact operations that turn on and off when current flows through the relay or switch, respectively, according to a typical relay contact operation display example. In the circuit shown in Figure 4, photodetector 1
Only when light enters o- or 11 and operates, Zl
Alternatively, the Z2 contact closes and supplies the voltage to the output terminal 15.16, so that the voltage from the photodetector 10.11 becomes the same. That is, when the panel is perpendicular to the incident light, the contact operation of switch Z3, Il:
is turned off, and no voltage is supplied to the output terminal.

This article has described the on-off operation of the pivot power supply in intermittent tracking, but the configuration related to the panel and drive will be explained in the fifth section.
As shown in the figure. Panel 2 is connected to gear 18.1 via arm 21.
9, and gears 18, 19 are driven by a motor 20. The motor is supplied with power supply voltage from the circuit described in Figure 4. The panel tilt angle changes with the rotation of the motor, but two stoppers are installed on the side of the panel, and when the panel tilt angle reaches an angle corresponding to the winter solstice or summer solstice, a limit switch 2 installed at that angle position
6. Two stoppers come into contact at 25.

The rotation direction of the motor 20 is reversed by contact operation of the limit switches 25 and 26. This is because, for example, after the summer solstice, the sun's altitude becomes lower, so sunlight hits the detector 10 and the detector 11 is in the shadow, but after the winter solstice, the sun's altitude increases and hits the detector 11. This is because the detector 10 is in the shadow.

Therefore, if it is detected at 10, it is necessary to increase the panel inclination angle. Conversely, when light is detected at 11, the panel inclination angle needs to be reduced. Furthermore, in this device, when a strong wind blows from the back of the panel, by turning the manual gear 18, the panel can be made almost horizontal to the ground and protected from the strong wind.

FIG. 6 shows an embodiment in which a large number of panels are linked to track the sun. An arm 22 of each panel is attached to a shaft 24 connected to a gear 18, and the motor 20 is rotated to rotate the shaft 24 connected to the panel, thereby changing the oblique angle of a large number of panels. Even in this case, if the gear 18 is manually turned during strong winds, many panels can be made horizontal at the same time and the influence of the wind can be reduced. 23 is a wheel that allows the end portion to move when the panel is rotated.

FIG. 7 shows a circuit for reversing the motor between the summer solstice and the winter solstice. During tracking, when light enters the photodetector 10, the detector 11
Since it is in the shadow, the output from the detector 10 is larger, and the output from the photodetector 11 is smaller, so the photoelectric switch Z1
is on, Z2 is off. On the contrary II
When the K light is incident, Z2 is turned on and zl is turned off. zl
When is on, relay 27 (denoted as X in the figure) is activated, Z2 is turned off, and relay 28 (denoted as Y in the figure) is disconnected. Therefore, motor terminals 29 and 30 are subjected to high and low voltages, respectively. In this state, when the panel becomes perpendicular to the incident light and the output signals 10 and 11 become equal, Zl occurs as shown in FIG.

Since z2 is cut off, no voltage is supplied to 15.16,
Motor stops. If the limit switch 26 is turned on while current is flowing through the relay 27 (at the summer solstice or winter solstice, and the stopper 24 attached to the panel is in contact with the limit switch), the current will no longer flow through the relay 27, and the current will not flow until now. Current flows through the relay 28 where current did not flow.

When relay 28 is activated, high voltage from 15 is applied to terminal 30 of the motor, and conversely low voltage is applied to terminal 29. Therefore, the motor reverses when limit switch 26 is turned on. Conversely, when the limit switch 25 is turned on, the relays 27 and 28 are turned on and off, respectively, and the motor rotation direction is reversed again.

The above is a description of a device that automatically adjusts the panel inclination angle in the north-south direction intermittently once a day on sunny days so that it is perpendicular to the solar altitude. Next, a device that can arbitrarily vary the tracking cycle when tracking the sun intermittently will be described. This is the same except for the previous solar detector.

FIG. 8 is a diagram explaining the principle of this device. One solar altitude detector 3, 32 is installed at both north and south ends of the panel. The solar altitude detector consists of a pinhole 33 and a light spot position detector with a photodiode layer formed on the bottom.
An electrical output proportional to the solar incident light and the deviation from the vertical plane of the panel can be obtained. The motor is rotated according to the magnitude of the electrical output from the solar altitude detector 31, and when the solar incident light becomes perpendicular to the panel and no output signal is output from the solar altitude detector, the motor rotation is stopped. to stop solar tracking. When the electrical signal from the solar altitude detector exceeds a certain value, it becomes a voltage that can be used on the go.
By making this constant value variable, the intermittent tracking cycle can be changed arbitrarily.

FIG. 9 is an explanatory diagram of the solar altitude detector. 37 is a slit with a rectangular cut in the north-south direction, and 38 is a filter that cuts out excess light.

33 is a pinhole, and 36 is a photodiode layer.

34 and 35 are electrodes. Sunlight shines through the slit 37 near noon. Photodiode 36 passes through pinhole 33
That corresponds to point 39 above.

FIG. 10 shows the relationship between the photodiode, electrode, and light spot. Since the photocurrent from the light spot 39 to the electrodes 34 and 35 is proportional to the distance between the electrodes and the light spot, measuring the voltage difference from the electrodes 34 and 35 determines the distance from the light spot to the center line, that is, the solar incidence. The angle of deviation between the light and the vertical plane of the panel can be seen. 11th
The figure is an explanation of the signal processing system of the photodetector shown in FIG. 10. Here, Y1+Y2 is a constant distance between the electrodes.

FIG. 12 is a diagram illustrating the relationship between the number of days for thread suspension and the input and output lightning pressure when using such a solar altimeter. After the solar tracking is completed, that is, after the panel inclination angle correction is completed, the solar altitude detector output voltage increases from Opol)A- as the solar altitude changes.

A threshold is set at the output voltage (constant) corresponding to the solar altitude change of tracking period (days) x 1 day, and the output power obtained above this threshold is shown in Figures 4 and 7. 1 drive a switch or relay. As explained earlier, when the solar altitude exceeds a certain value, the drive motor rotates,
If the rotation direction is reversed using a limit switch installed at the summer solstice and winter solstice positions of the panel tilt angle, intermittent solar tracking and tail tracking cycles can be arbitrarily changed to automatically adjust the panel tilt angle. A tracking device can be realized.

According to this embodiment, the following effects can be obtained. .

α) Compared to the conventional solar power generation system in which the panel tilt angle is constant, the light collection efficiency improves by about 4 times on sunny days.

(2) The sun can be tracked with a simple device without the need for a large-scale tracking device such as calculations for sun tracking.

(3) The control circuit is simple.

(4) The sun can be tracked intermittently in the north-south direction. The tracking period in this case is variable.

(5) Even many panels can track the sun simultaneously with a single shaft.

(6) In case of strong winds, the panels can be manually lowered to the ground to protect the nokunel.

(7) Only one drive is required on sunny days, so less power is required.

Figures 13 and 14 show a modification of the invention regarding panel movement. In the previous embodiment, an arm attached to a panel was connected to a single shaft, and the shaft was rotated to change the angle of inclination of a number of panels. On the other hand, in Figures 13 and 14, a car installed on the back of the panel is moved on the rail to change the panel inclination angle.

A gear 41 is rotated by a motor, and a wheel 43 is pulled by a shaft 49 to move on the rail and change the angle of the panel.

Limit switches 44 and 45 are installed on the rail at the anti-solstice or winter solstice positions, respectively. This tracking control circuit is the same as the circuit described above. In FIG. 14, a drive motor is attached to the back of the panel, and a wheel and an arm for changing the panel angle are also attached to the back. According to this modification, it is possible to change the inclination and angle of a large number of panels at the same time as in the previous example, and because the panels slide on rails, the tracking structure becomes simpler than when a shaft is used.

〔Effect of the invention〕

According to the present invention, the north-south inclination angle of the solar panel can be changed according to the solar altitude, and the light collection efficiency on a sunny day is higher than that of conventional power generation methods in which the inclination angle is fixed. is improved by 4 times. Additionally, it can track the sun intermittently without the need for a special computer or large-scale equipment, and requires less power because it is driven only on sunny days. Furthermore, if necessary, multiple panels can be driven by a single shaft to track the sun.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams showing how the solar light tracking photodetector used in the present invention is installed, Figure 3 is a diagram showing details of the solar detector and its output characteristics, and Figure 4 is an intermittent A circuit diagram showing a tracking drive power source and a switching circuit, FIG. 5 is a diagram showing the configuration of the power generation panel and the drive mechanism, FIG. 6 is a diagram showing the configuration of one drive mechanism that interlocks multiple panels, and FIG. 7 is a circuit diagram of the motor rotation direction control circuit, Fig. 8 is a diagram showing the panel and sunlight detector for changing the tracking cycle, Fig. 9 is an enlarged explanatory diagram of the sunlight detector, and Fig. 10 is a diagram of the light detection. Figure 11 is a diagram explaining the processing of the detection signal. Figure 12 is a diagram showing the relationship between the output voltage from the photodetector and the number of days from the end of tracking. Figures 13 and 14 are the panel diagrams. Figures showing other methods of changing the tilt angle; a<1sg is a schematic diagram of a conventional solar power generation device with a fixed solar panel tilt angle; FIG. 16 is a schematic diagram of a conventional tracking type solar power generation device; Figure 17 is a diagram showing how the amount of solar radiation changes depending on the presence or absence of tracking on sunny and cloudy days, Figure 18 is a diagram showing how the annual amount of solar radiation changes depending on the presence or absence of tracking, and Figure 19 is the solar altitude and direction. FIG. 20, a graph showing the temporal change in the angle, is a diagram showing an example of measuring the temporal change in the amount of solar radiation. 1...Sunlight, 2...Solar cell battery, 2A...
Stopper, 3... Frame, 4... Power supply, 5... D-
A converter, 6-9... Gear, 10.11... Sunlight detector, 12... Photocell, 13... Slit,
14...Power supply, 15...Power terminal (high voltage side), 16
...Power terminal (low voltage side), 17...Photoelectric switch,
18.19... Gear, 2 (1... Motor, 21...
・Rotating axis, 22...arm, 23...car, 24...
・Shaft 25.26--Limit switch, 27.
28... Relay, 29.30... Motor power terminal,
3, 32... Solar altitude detector, 33... Pinhole, 34. 35... Electrode, 36... Photodiode layer, 37... Slit, 38... Filter, 39...
... Light spot, 40 ... Electrode center line, 41 ... Gear, 4
2... Worm, 43... Gear, 44.45...
Limit switch, 46.47...Rail, 48...
・Car, 49...drive shaft.

Claims (1)

[Claims] 1. In a tracking solar power generation method in which the panel angle is adjusted so that the solar panel surface is approximately perpendicular to the sunlight, the panel angle may be adjusted intermittently only in the north-south direction. Features of tracking solar power generation method. 2. The tracking solar power generation method according to claim 1, characterized in that the intermittent adjustment interval is one day, and the adjustment time is around solar midpoint. 3. The tracking solar power generation method according to claim 1, characterized in that the intermittent adjustment interval is one month, and the adjustment time is around solar midpoint on that day. 4. A tracking solar power generation method according to any one of the above claims, characterized in that intermittent adjustment is performed only on sunny days. 5. In a tracking type solar power generation device that adjusts the panel angle so that the solar panel surface is approximately perpendicular to the sunlight, a means for measuring the solar altitude by detecting direct incident light only on sunny days at a fixed time. , a solar tracking type comprising a drive means that moves the panel in the north-south direction according to the output of the solar altitude measuring means to make it almost perpendicular to the sunlight, and is characterized in that the panel angle is adjusted intermittently only on sunny days. Photovoltaic device. 6. The tracking type solar power generation device according to claim 5, wherein the drive shaft of the drive means is arranged in the east-west direction and drives a plurality of panels simultaneously. 7. In claim 5 or 6, the solar altitude measuring means includes a detector that detects changes in the solar altitude of more than a certain level with the passage of time and time, and that can set various ranges of the change; A tracking type solar power generation device characterized by driving and adjusting panels at intervals.