Research and Implementation of The Dual Mode Solar Automatic Tracking System

Han Shunjie College of Electric and Electronic Engineering

Changchun University of Technology Changchun, P. R. China

hanshunjie@mail.ccut.edu.cn

Han Yue College of Electric and Electronic Engineering

Changchun University of Technology Changchun, P. R. China hanyue0504@163.com

Han Meng College of Electric and Electronic Engineering

Changchun University of Technology Changchun, P. R. China

hanmeng198729@163.com

Abstract—in order to more fully and high efficiency in the use of solar energy, it is generally used to track the sun way to maximize more light energy. There is a kind of design scheme about solar energy automatic tracking device in this paper. This method combines the advantage of optoelectronic tracking detection mode and Calculation of sun position tracking mode, then put forward a kind of dual mode solar automatic tracking systems. The system can round-the-clock to track the sun according to the sun changes of the trajectory path., which enables the power efficiency greatly increased. This method has important significance in lower solar power cost; promote the application of solar energy on the communication, the wild monitoring, civil and so on.

Keywords-Dual mode; Photoelectric detection of trace; Calculation of sun position; Stepping motor

I. INTRODUCTION Solar energy is a kind of clean renewable resources, which

has the superiority of mineral energy, and solar energy resources are very rich that is the most widely application in the renewable energy.

Although solar total energy is very big, but we couldn't keep the sun always perpendicular to the panels due to the use of solar energy by natural conditions and the influence of the sunshine, so it doesn’t get universal use because of the solar panels is expensive and the photoelectric conversion efficiency is low. The trace system is a combine mode, combining the advantage of optoelectronic tracking detection mode with Calculation of sun position tracking mode. Using optoelectronic tracking detection mode in sunshine, comparator circuit of photosensitive diode which is transmitter adjusts the position of sun, cooperating with motor to control part of machinery which real-time traces the sunshine, where

the mode can achieve sunshine efficiently. Using Calculation of sun position tracking mode in wet weather, position and altitude angle are calculated by software to track the sunshine and ensure the stability of receiving.

II. THE DESIGN SCHEME OF SUN TRACKING SYSTEM The present study direction is how to track and absorb

solar more effectively and longer in order to receive solar energy fully and effectively. Usually the solar tracking mode has two kinds: one is photoelectric detection tracking mode, which tracking through the instant detection of the sunlight; another is sun Angle tracking mode (also called Calculation of sun position), which fixed rotation and tracking through the predetermined function to compute the position of the sun. The two models all have advantages and disadvantages, so the scheme of this paper is tracking to the sun, which combined with the advantages of the two kinds of modes. According to the different intensity, it adopts the corresponding tracking mode to track the sun.

The system is based on computers as control core, receiving the sun position signal output through the photoelectric detection module, and calculating the theoretical value of the height and azimuth Angle of the sun combined with the sun trajectory tracking module, then it controlled the step motor rotation, and achieved the tracking of the sun.

First we use photosensitive diode system to test this moment is the day or night. If it was night, the system will not run, with battery power supply; If it was the day, the priority is to use the photoelectric detection tracking to track. If the light of the receiving photosensitive can't into corresponding strength of current, the SCM system will be transferred to Calculation of sun position to control the solar panels to

978-1-4577-0547-2/12/$31.00 ©2012 IEEE

deflect, Then start timing, from external clock read time to correct azimuth, it ensure that the system full-time working process.

A. The plan of Photoelectric detection tracking model The model is to use light intensity detection photosensitive

semiconductor, determined the light intensity to the extent of the reboot the entire system. And then it is to use the photosensitive sensor to detect cloudy sunny, determined the requirement whether to start tracking the mode of photoelectric detection. If it should meet the requirement, it senses the sunshine incident direction by the photosensitive sensor of the solar receiver, the electrical signals generated by the op-amp then enlarges to microcontroller, then to change the solar panel orientation by single-chip microcomputer control motors, then reach the predetermined requirement.

Figure 1. The principle diagram of photoelectric detection tracking mode

Because photosensitive diode has the linear current output in a wide range of incident intensity of illumination, response speed also quickly, it has high sensitivity for wide-area range of wavelengths of light, small, lightweight, and vibration resistance, impact resistance, so we choose photosensitive diode as the sensor.

The system adopts the seven photosensitive diodes, one of the photosensitive sensors is used to detect the night or day, one of the photosensitive sensors is used to test cloudy, rainy day or a sunny day, and the other five is used to test the sun incident direction and navigation for solar panels. The priority of photosensitive diode which used to detect the night day is the tallest, then next is the photosensitive diode which used to test cloudy, rainy day or a sunny day, the last stage is the photosensitive diode which used to test the location of the sun.

Figure 2. The model of photoelectric detection tracking

B. The plan of Calculation of sun position tracking model If it is a cloudy day, we will start Calculation of sun

position tracking model. It gets instant time by single-chip microcomputer chip read from the clock; calculate the sun Angle through the function within. It controls the motor operates according to calculate a track and track the sun through the MAX7219 drive time display.

Figure 3. The principle diagram of Calculation of sun position tracking

model

To study and establish the calculation of Calculation of sun position, the first thing is to determine the trajectories of the sun. We use two parameters to determine the trajectory of the sun: The height of the sun and the sun azimuth Angle.

The height of the sun Angle: The height of the sun Angle is the Angle between the means from the center of the sun to the local and the direct light horizontal plane, its value at 0 degrees to 90 degrees. It is 0 degrees when the sun had just come out and just fall, then the twelve o 'clock midday, it is 90 ° when vertical objects see the shadow.

The sun Angle: The sun azimuth is to point to the sun location position, refers to the sun's rays in the Angle of the plane of the projection and local meridian. Azimuth is zero when the sun in south direction, the negative value is from south to east; the positive value is from south to west.

In the 365 days of the year, set the corresponding interval is in [0,π ].

The day Angle is:

2 ( 1)365

no

Rπθ −= （1）

nR is years of date sequence, then n can take January 1 to 1,take May 31 to 365, use radian to said red weft δ :

0.00689 0.39951cos 0.07208sin 0.0068cos 20.0009sin 2 0.00269cos3 0.00151sin 3

o o o

o o o

δ θ θ θθ θ θ

= − + −+ − +

Set the height of the sun and the sun azimuth Angle are hθ and

pθ respectively, set the geographical latitude for D , then we have the astronomy formula:

sin sin sin cos cos cosh D D Wθ δ δ= + （2）

cos sinsincosp

h

Wδθθ

= （3）

sin sin sincoscos cos

hp

h

DD

θ δθθ

∗ −=∗

（4）

Through the above introduction of the height of the sun and the sun azimuth Angle we can know that only need to determine the longitude and latitude, we can calculate the specific position of the sun at the time through the above formula. And in a year of time, the value is determined and the only one. This function can be realized through the microcontroller, we will set the coordinates of numerical to a fixed value, and get the instant time by reading the clock chip the flat position of the sun and Angle value can be obtained for anytime.

III. DESIGN HARDWARE OF SYSTEM The core of the system would use the C51 microcontroller,

the solar tracking system consists of optical sensors, microcontrollers, clock chip, display circuit, amplifier circuit, motor, solar panels.

The solar tracking system would translate into tracking mode when the illumination is strong,, and the light-sensitive sensor which detect to the position of sun would amplifies and send the signal to the microcontroller , the microcontroller controls the motor running which make the solar panels aimed at the direction of sunlight.; The solar tracking system would translate into the tracking mode which depending on calculation of sun position, the microcontroller reads the time from the clock chip, using a function to calculate azimuth of the sun, equipped to control the motor running, which make the solar panels to run a fixed track and receive the sun.

Hardware is as follows:

Figure 4. The diagram of system hardware

IV. DESIGN SOFTWARE OF SYSTEM The design part of the program include: optical detection,

tracking of calculate of sun position, the clock chip program, LED display program. Picture of the main program as follows:

Figure 5. System programming flowchart

V. EXPERIMENTAL ANALYSES

A. The result of optical tracking as follow:

Figure 6. Figure 4 the contrast curve of actual data and test data

We would found that the total solar radiation on average: tracking is about 23.16MJ• , the fixed south to 36 degree is 16.86MJ• through calculate the measure of the result.

B. Contrast analysis results Comparison of the result of calculating of the elevation

angle and azimuth of the sun in the mode of tracking depend on calculate the position of the sun and SkyMap as follow:

We would found the largest deviation is 1.7 degrees above the table. Therefore, the calculating of the elevation angle and

azimuth of the sun in the paper is meeting the requirements basical

VI. CONCLUSIONS

The system is stable and reliable, high sensitivity, the per formant of resistance wind is good, practical, and would achieve the wide range and all-weather on the tracking of sun; The system is suitable for practical application of solar panels, spread easily, provide an important evidence which to improve the utilization of sunlight.

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TABLE 1 THE CALCULATION RESULTS OF THE SOLAR ALTITUDE ANGLES AND AZIMUTH PROGRAM AND THE COMPARISON RESULTS WITH SKY MAP

(CHANGCHUN)

The values of skycap

The value of calculate in this

paper Elevation

angle azimuth Elevation angle azimuth

1 -46.57 336.36 -46.31 334.93 2 -31.36 53.36 -32.17 52.75 3 17.03 88.35 17.31 88.02 4 64.27 141.1 63.68 139.6 5 44.08 252.44 44.05 251.26 6 -6.49 285.48 -6.32 283.75